Introduction
This website was designed to introduce the traveler to the concept of the date line and how it relates to Halacha. Every effort has been made to make the subject understandable to all. While some may undoubtedly find the material confusing, an attempt was made to simplify as much as possible.
With the advent of extensive travel to the Far East by the Mitzva observant, halacha as it relates to the date line has become a topic of interest. Halacha sensitive Jews have been presented with a vast array of halachic questions ranging from when to daven midflight to when Shabbos is to be observed in various locations.
Because there are such differing opinions by leading poskim on almost any specific question, we have based the halachos on conclusions reached by Rabb Yisroel Taplin of Beth Medrash Govoha in Lakewood, who has researched the topic extensively, has personally discussed the matter with the greatest poskim of the past half century, and who has written a 700 page sefer on this subject, Sefer Taarich Yisroel. His conclusions are not the final word on the subject. All are advised to discuss the matter with their own posek as they relate to halacha lema’aseh. This website should however be a good introduction to the issues and offer the reader a solid background to enable one to know wherein lie the questions.
The website is divided into the following sections:
Where is the Date Line
International Date Line vs Halachik Date Line
How to Use the Location and Time Charts
In addition we have attached 2 appendices to this website.
Appendix A – Location and time charts that can be used on trips to and from the Far East that are helpful in planning time observance of mitzvos
Appendix B- The original text of the English adaptation of Sefer Taarich Yisroel published in 1999. While on the one hand it offers a deeper understanding of much of the subject, some of the practical halacha lemaaseh questions have changed as a result of the introduction of transpolar flight,
Overview
The Great Bar Mitzvah Paradox
Rabbi and Mrs. Cohen, teachers in the Hebrew Day School of Hawaii, would like to celebrate the bar mitzvah of their twins, Moshe and Aharon, in Yerushalayim. Rabbi Cohen’s elderly parents live in New York, while Mrs. Cohen’s parents live in Hong Kong. As they plan to celebrate the bar mitzvah in Eretz Yisroel, the Cohens decide that Rabbi Cohen will take Moshe to visit his parents in New York on the way to Eretz Yisroel, and Mrs. Cohen will take Aharon to Eretz Yisroel via Hong Kong to enable her parents to partake in the simcha.
The bar mitzvah is scheduled for Thursday, 7 Adar. On Monday, 4 Adar, they board their respective flights, the father and Moshe to New York and then to Eretz Yisroel, and the mother and Aharon to Hong Kong and then on to Eretz Yisroel.
Each leg of each flight is about 12 hours.
The eastbound flight to New York departs Hawaii on Monday at 1 p.m. local time, flies into the sunset and through the night, and arrives in New York 12 hours later, on Tuesday morning at 6 a.m.. (1 a.m. Hawaii time plus 5 hours, as New York is 5 hours ahead of Hawaii). They visit their relatives and leave New York that evening. After a 12-hour stopover, they depart New York at 6 p.m., they observe Tuesday’s sunset, fly through the night, and arrive in Eretz Yisroel on Wednesday at 1 p.m. (6 a.m. New York time plus 7, as Eretz Yisroel time is 7 hours ahead of New York). The bar mitzvah is scheduled for the next morning.
In the meantime, Mrs. Cohen, traveling with Aharon, leaves Hawaii at the same time as her husband, 1 p.m., in a westbound direction. They land in Hong Kong 12 hours later, where the local time is Tuesday 7 p.m. (Hawaii time 1 a.m., minus 6, as Hong Kong time is 6 hours behind Hawaii. However, because they crossed the International date line the day advances from Monday to Tuesdya). The entire flight took place during daylight. Mrs. Cohen visits her parents, and after a 12-hour stopover in Hong Kong, she and Aharon depart to Eretz Yisroel the next morning. local time Wednesday 7 a.m. Being that this flight is also in a westbound direction, they are flying “with the sun,” so that when they arrive 12 hours later in Eretz Yisroel, the local time is Wednesday 1 p.m. (Hong Kong time 7 p.m., minus 6, as Eretz Yisroel time is 6 hours behind Hong Kong time.)
Rabbi Cohen and Moshe arrive at the same time, and together they take a cab to Yerushalayim.
That night, as they compare notes of their journeys, something fascinating surfaces. As Rabbi Cohen flew eastward, “against the sun,” time kept on advancing. He and Moshe saw two sunsets along the way. Mrs. Cohen and Aharon, on the other hand, flew westward. As they flew with the sun, time kept moving back, resulting in their experiencing only one sunset since leaving Hawaii.
While it may be true that both Moshe and Aharon consider their landing time in Israel to be Wednesday 1 p.m., their days coincide only because Aharon crossed the International Date Line, an imaginary line in the Pacific that pushed the day forward as he crossed it. The question is, does halacha recognize this event? If halacha does not, but rather considers a day change to take place only at sunset, Moshe and Aharon’s days do not coincide.
Moshe lived through one more sunset than his twin Aharon did. Is he, in fact, a day older? Aharon observed a Monday night sunset shortly after he landed in Hong Kong, but he never did get to see a Tuesday night sunset. Is today in fact his Tuesday, 5 Adar? And if it is Wednesday, how did he get there without having seen a Tuesday sunset?
If we carry the argument to its logical conclusion, that Moshe is in fact older than Aharon by a day because he experienced an extra sunset, then as they both stood at the airport in Eretz Yisroel after they landed, for Moshe it was Wednesday and his bar mitzvah would be the next day, Thursday, while for Aharon it was only Tuesday, and his bar mitzvah would not take place for another two days — on his Thursday, which is Moshe’s Friday. Is that possible? When Friday night comes for Moshe, will it be Thursday night for Aharon? When Moshe is making Kiddush, can it be a weekday for Aharon? That is clearly impossible. How, then, do we reconcile Aharon’s calendar?
The short answer to the Cohens’ question lies in the fact that someone crossed the date line somewhere along the way.
As the Cohens traveled, two of them east and two of them west, together they circumnavigated the world. Only one pair of them crossed the date line. I hesitate to say which one did as this is, in fact, a major disagreement among poskim. The Chazon Ish would claim that Mrs. Cohen and Aharon crossed the date line as they approached Asia, catapulting them a day forward, while other poskim would say that Rabbi Cohen and Moshe crossed the date line shortly after they took off from Hawaii, somewhere between Hawaii and California, moving them backward in time. Just how this works and why the poskim disagree is the subject of the website. The fact of the matter is that one of them crossed the date line, resulting in their simultaneous arrival in Eretz Yisroel on the same day regardless of how many sunsets each experienced.
Welcome to the World of the Date Line in Halacha.
The date line question in halacha was not seriously dealt with until the Jews fleeing the Nazis during World War II found themselves in the Far East. They were unsure where the date line was and on which side of it they stood. The questionwas sent to Eretz Yisroel by telegram, and two major conflicting opinions emerged — opinions that severely impacted their daily lives by concluding which day to keep Shabbos and on which day to fast on Yom Kippur.
In broad strokes, the date line question can be broken down into two major issues.
One: Is there a halachic date line? And if so, where is it?
Two: Halachically, what happens when you cross the date line?
The first question regarding where the date line is has major ramifications regarding the determination as to what day of the week it is at each point on the planet. Just to cite one example, according to the Chazon Ish (CI), Shabbos in Japan is to be observed on the day that the Japanese call Sunday. According to Rav Yechiel Michel Tukatzinsky (RYM) and most other poskim, Shabbos in Hawaii is to be observed on the local Friday.
The second question, what impact does crossing the date line have on halacha, has created an entirely new area of study heretofore unexplored.
A few cases in point:
One is on a flight from New York to Hong Kong. On Monday afternoon, at 3 PM local time, he davens Mincha. Shortly thereafter, he crosses the date line. The day is pushed forward, and local time is now Tuesday 4 PM Must he daven Mincha again? Furthermore, since it is now Tuesday, and he never wore Tefillin on Tuesday, must he don them for Mincha?
Or consider a baby born in New York on Monday, 2 Kislev, who travels westward to have his bris in Hong Kong the following Monday, 9 Kislev. When this baby date line crosses the and the day is pushed forward, by the time it is Monday, 9 Kislev, in Hong Kong, for this baby it is still the seventh day! What difference does it make if he crossed some invisible geographic line in the Pacific Ocean? Bottom line is that this baby is only seven days old. May we perform the bris on Monday?
On eastbound flights, the day is pushed backward as the date line is crossed; in other words, the calendar shows the date on the east side of the date line to be a day earlier, hence the day repeats itself. All the above questions then arise in the reverse. If one davened Mincha on Monday, and he then crosses the date line in an eastbound direction, thereby pushing the day/date back to Sunday, when it is time for Mincha the next day, on Monday, in New York, must he daven again? After all, he davened Monday’s Mincha already! On the other hand, as far as this individual is concerned, this “second” Monday is a new day for him. The questions are endless. Interestingly, contemporary poskim have very different opinions on each case. Their understanding of which mitzvos are determined by the calendar day/date and which mitzvos are determined by one’s personal day based on sunrise and sunset experiences are quite diverse.
Why Must There Be A Date Line At All?
Before directly addressing this matter, it is important to gain an appreciation of the geography involved, a subject that some may have found distasteful back in ninth grade, but so very essential for an understanding of the dateline. Let us reacquaint ourselves with how one’s latitude affects seasons and the number of daylight hours at a particular location, and how one’s longitude determines day/date and the hour of the day at any particular location.
The vertical lines on the globe are longitude lines. When traveling in an east-west or west-east direction, you are changing longitude. Longitude is measured by 360 vertical lines that go from the North Pole to the South Pole. However, unlike latitude, longitudinal lines are not parallel to each other. At the Equator, the widest point of the Earth, which measures approximately 25,000 miles in circumference, the distance between each longitude degree is approximately 70 miles. As you move away from the Equator toward the poles (as latitude increases), the circumference of the Earth decreases to the point where all 360 longitude degrees converge at the Poles, and the distance between longitude lines is reduced to zero. Geographers have set up a system of plotting points on the globe using longitude and latitude coordinates. The point where a specific longitude meets a specific latitude is called its coordinates.
As we mentioned above, latitude degrees are measured by their distance from the Equator with the Equator (the midpoint between the North and South Poles) being the zero degree mark. As you go north or south away from the Equator, each 70 miles adds one degree to your latitude, until you reach the pole at 90 degrees north or south.
Unlike latitude, longitude has no natural starting point. International convention has determined that the city of Greenwich in England be the starting point at zero degrees. As you move west toward the Americas, the longitude lines are noted to be West, while as you move east toward Asia, the longitude lines are noted to be East.
The East and West longitude points meet at the 180 degree mark. There are 180 degrees east and 180 degrees west. Together, you have the full 360 degrees of the circle.
The 0 longitude point in Greenwich, England is called the Prime Meridian, while the 180 degree point is called the AntiMeridian. This point is what is commonly referred to as the International Date Line (IDL), the point at which the day/date moves forward as you cross it in a westerly direction, and the day moves backward as you cross it in an easterly direction. (Note: While the 180th meridian should in theory be the IDL, and for the most part it is, for convenience sake, world convention has made provisions for the IDL to zigzag around country borders so as not to have the date line run through a single landmass).
The 360 longitudinal lines are divided into 24 sections, each measuring 15 degrees.
These sections or time zones allow for the sun to be overhead at each location at its own noon. So that when you travel a distance that crosses 15 longitudinal degrees, you’ve moved into another time zone.
The distance between New York and Jerusalem is approximately 109 degrees. Divide 109/15=7.2. The time is Jerusalem is 7 hours ahead of New York.
Los Angeles is located at the 118W meridian, 44 degrees west of New York (74W). 44/15=2.9. Hence, the time is Los Angeles 3 hours behind New York, or 10 hours behind Jerusalem.
So why must there be a date line? Without the date line, people who travel west around the world would discover that when they returned home, it would seem as though an extra day had passed. This situation actually happened to Magellan’s crew when they returned home after their circumnavigation of the Earth.
Here’s how the date line works: Let’s say you fly from the United States to China, and suppose you leave the United States on Tuesday morning. Because you’re traveling west, the time advances slowly thanks to time zones and the speed at which your airplane flies. As you fly westward “with” the sun, the apparent time change slows down as time zones to the west move the clock backward. However, as soon as you cross the date line, it’s suddenly Wednesday.
On the return trip, you fly from China to the United States. You leave China on Monday morning, but as you cross the Pacific Ocean, the day progresses quickly as you cross time zones moving eastward. But as soon as you cross the date line, the day changes back to Sunday. The flight lands in New York on the same day of the week as it took off!
International Date Line (IDL) vs. Halachik Date Line (HDL)
As mentioned above, international convention accepted a most convenient point on Earth, somewhere in the middle of the Pacific Ocean, to place the date line. Can Halacha accept it? And if not, why not?
While the Gemara may make no mention of a date line, Halacha which addresses every single possible aspect of life must have had a date line before the international community decided on one in 1884. Where halacha determines it is might elude us, but one must exist.
Furthermore, the date line accepted by international convention changes from time to time. The date line is not defined by international law. Countries are free to choose the date and time zone that they wish to observe.
For example, when the Republic of Kiribati gained independence from being a British colony in 1979 some of the islands were on either side of the date line. They corrected this anomaly in the eastern half of Kiribati by skipping January 1, 1995 and ever since Kiribati has been the first country to enter the New Year.
In 2011, Samoa changed the time zone from GMT-11 (Greenwich Meridian Time minus 11 hours) to GMT+13 by shifting the date line to the west and removing December 30, 2011 from the calendar. They did this to facilitate trade with Australia and New Zealand.
How would halacha deal with arbitrary government decisions to changed days, removing a day from the week? What would happen to Shabbos of that week?
In truth, there are poskim who do in fact accept the IDL. Lubavitch shlichim worldwide follow the local day of the week. While this view may have some halachik support, the vast majority of poskim do not concur.
There is no discussion in the Gemara that mentions date lines directly. Contemporary poskim have been grappling with this problem for the past eighty years. Although they have suggested more than 10 possible locations for the Halachik Date Line (HDL), in practice, only 3 are entertained by poskim.
Baal Hamaor / Chazon Ish (CI) – A number of Rishonim interpret a Gemara in Rosh Hashana Daf 20 in a manner which seems to indicate that there is in fact a date line located 90 degrees east of Jerusalem. This point at the 125.2E meridian (Jerusalem 35.2+90=125.2) is referred to as the Baal Hamaor’s date line, as he is the one who clearly articulates this position in his commentary on the above mentioned gemara. This position has been adopted by the Chazon Ish (CI) albeit with minor modifications; where the 90 degree line located at the 125.2E meridian cuts through a single landmass, the line hugs the Asian coastline. Hence, Eastern portions of Korea, Siberia and Australia that lie east of 125.2E are still considered west of the CI’s date line. This concept, that the date line will not cut a landmass but is rather drawn toward the mainland is called “Gereira”.
Rav Yechiel Michel Tukatzinsky (RYM)– Other Rishonim understand the Gemara in Rosh Hashana differently (See the appendix to the Artscroll Schottenstein Talmud Rosh Hashana Daf 20 for a detailed explanation of these interpretations), and do not agree with the 125.2E date line. Most poskim concur with the view of Rav Yechiel Michel Tukatzinsky who argues that the halachik date line (HDL) in fact lies at a point 180 degrees from Jerusalem, half-way around the center point of the world, Jerusalem, at the 144.8W meridian.
This line runs through the eastern portion of Alaska. (Note: if we apply the Gereira principle mentioned above, that the date line does not cut a landmass, then western Alaska would be drawn eastward and would be considered on the American side of the date line. The Gereira concept is quite controversial, and although accepted by CI, again, most poskim do not concur.)
Rav Isser Zalman Meltzer – Halacha accepts the IDL.
Where The IDL And The HDL Do Not Coincide
Look at a map of the Pacific Ocean, with America on the east and Asia on the west. We will draw the 3 date lines mentioned above and see how they may affect how we treat Halacha in a practical way.
Let us first study day changes using the International Date Line as our point of reference. As the sun sets over the IDL on Thursday night, let us say at 6 PM, the day/date is pushed forward, and 6 PM Thursday becomes 6 PM Friday, the onset of Shabbos. ( We are using sunset as the point of day change, not midnight as accepted by the international community). As the sun travels west, each subsequent hour that the sun travels ushers in another hour of Shabbos. By the time sunset reaches Japan some 3 hours later (Japan lies at 140E, 40 degrees or 3 times zones west of the IDL), Shabbos begins in Japan. One hour later, as sunset approaches China at 125E, points west of China are still Thursday night/Friday, while points east of China already enjoy Shabbos. As the sun travels around the world for the next 20 hours, Shabbos will begin as sunset reaches each point, until finally, when the IDL experiences its next sunset, that will be Motzoei Shabbos or the beginning of Sunday.
The Chazon Ish however does not see it that way. His HDL is at 125.2E. Shabbos begins only when sunset reaches the 125.2 HDL, at the coast of Asia. All points east, are still considered Thursday night/Friday. So that for the entire area between the IDL (180) and the CI HDL (125.2E) it is still Thursday night/Friday. Those who follow local time using the IDL, consider it Friday night/Saturday while the CI considers it Thursday night/Friday.
Conversely, when sunset Saturday night reaches the CI HDL, the Chazon Ish’s Sunday begins. All points west of that, are still Shabbos. Japan which lies is this in-between zone, between the IDL and the CI HDL, would therefore celebrate Shabbos on the local Sunday. Because the IDL advanced the day to Sunday while the HDL did not. Shabbos begins and ends in Japan 23 hours AFTER Shabbos begins and ends in China, rather than one hour before China.
On the other hand, consider the following. The RYM HDL at 144.8W lies about 35 degrees or 2 time zones east of the IDL. Hawaii, at 158W is one time zone west of the RYM HDL and one time zone east of the IDL.
As the sun sets at the RYM HDL on Thursday night and the day is pushed forward such that Thursday night becomes Friday night, Shabbos begins in the world. When sunset reaches Hawaii an hour later, Shabbos begins. However, international convention considers that to be Thursday night, as the day does not jump forward until the IDL, 22 degrees further west. Using the RYM HDL, Shabbos in Hawaii begins when sunset reaches it one hour after Shabbos at the HDL, and one hour before the start of Shabbos at the IDL. Using the IDL however, Shabbos would not begin until 23 hours later, as Hawaii, located one hour east of the IDL is at the very end of the world day, whereas following the RYM HDL it is located at the beginning of the day. The result is that in the 35 degrees between the RYM HDL and the IDL, Shabbos would in fact be on the local Friday. Note, that most of Alaska including Anchorage falls in this zone as well.
In summary, according to the Chazon Ish, in Japan and New Zealand, one would celebrate Shabbos on the local Sunday. One would consider the local Saturday to be an ordinary weekday. In Hawaii on the other hand, one would celebrate Shabbos on the local Saturday.
According to RYM, Hawaii and most of Alaska would observe Shabbos on Friday. The local Saturday would be a weekday. Japan and New Zealand however would observe Shabbos on their local Saturday.
The third opinion which follows the IDL would observe Shabbos on the local Saturday wherever it may be. There is never an IDL-HDL conflict.
Conclusion
As stated above, we are following the rulings of Rav Yisoel Taplin, author of the monumental work on this subject, Sefer Taarich Yisroel. Rav Taplin has personally discussed this question with most of the leading poskim of the past 50 years and has concluded, that insofar as the vast majority of poskim rule like Rav Tukatzinsky, that we treat the RYM HDL (144.8W) as the halachic dateline. Hence, all points west of Chitina, Alaska, (a small town in Eastern Alaska) are considered west of the HDL and must follow the Asian day. We do not apply the Gereira principle to the western portion of Alaska which includes most of Alaska’s larger cities- Anchorage and Fairbanks.
However, because of the severity of Shabbos, and the difficulty in taking a firm position in opposition to that of the Chazon Ish, with regard to Shabbos, most poskim recommend following both opinions on D’oraisa matters, while observing the main Shabbos on the day considered to be Shabbos according to RYM, as this is the majority opinion. More on this later.
Living Beyond the Date Line
We have shown that the majority opinion regarding the position of the date line is that of RYM at 144.8W. And for all intents and purposes we refer to this meridian as the HDL. However, with regard to Shabbos and D’oraisa laws, we consider the Chazon Ish’s 125.2E line as well.
In practical terms, how does this all play out?
According to RYM, Shabbos begins when the sun on Thursday evening sets over the 144.8W meridian, and Thursday night becomes Friday night. As the sun travels westward, as each point experiences sunset, Shabbos begins. Six hours after the sun set over the RYM HDL, the sun sets at a point 90 degrees west, at 125.2E, the CI HDL. The result is, that while RYM considers it to be Shabbos in Alaska, Hawaii and the Pacific Ocean, for the Chazon Ish, it is still Thursday night/Friday.
When Shabbos ends 24 hours (technically approximately 25 hours, as Shabbos does not end until tzeis hakochavim) after it began over eastern Alaska at 144.8W, and Sunday begins, to the Chazon Ish it is still Shabbos. Shabbos does not end until the sun sets (or more correctly tzeis hakochavim) over the 125.2E meridian some six hours later. Hence, while RYM considers it to be Sunday over the Pacific Ocean, to the Chazon Ish it is still Shabbos.
Another factor to consider is, that even though halacha may not recognize the IDL, the international community does. So that when the IDL and the HDL do not coincide, it can cause massive confusion. Let’s look at Hawaii which is located at the 158W meridian. This point lies 12 degrees west of the RYM HDL, and 22 degrees east of the IDL.
When Shabbos is ushered in on Thursday evening at sunset at the RYM HDL, and halacha pushes the day forward to Friday night, the international community considers that to be the Thursday night sunset. To the international community, the new day begins only at the IDL. So as the sun proceeds to set over Alaska and then Hawaii, the international community considers it to be Thursday night, while RYM considers it Friday night, where Shabbos sets in. The international community does not move the day forward until the IDL at which point, the HDL and the IDL coincide. But in all areas between these two points, the halachic day and the secular calendar day are different. To RYM, in this 35 degree zone, from 144.8W to the IDL at 180 degrees, that which the secular calendar calls Friday is in fact Shabbos. Conversely, what the secular calendar calls Saturday, RYM calls Sunday.
Similarly, in the 55 degree zone, between the IDL at 180 and the CI HDL at 125.2E, the international day is ahead of the CI day. Hence, in this area, what the world call Saturday is in the eyes of the CI Friday, and what the world considers Sunday is in fact Shabbos.
Bottom line- Japan and New Zealand which lie in this 55 degree zone are halachically problematic according to the Chazon Ish. He considers Shabbos to be on the secular Sunday, while the secular Saturday is the halachic Friday.
Rav Tukatzinsky has no problem with Japan and New Zealand as they both lie west of the IDL, so the secular day in those countries caught up with the halachic day. The western portion of Alaska and Hawaii on the other hand pose a challenge to RYM, as the secular Friday is in fact Shabbos, while the secular Saturday is really Sunday.
Practical Application for those spending Shabbos beyond the Halachic Dateline
One who is in western Alaska or Hawaii on Shabbos must treat Friday as Shabbos. Kiddush to be said on the secular Thursday night, Shabbos davening on Friday, and Tefilin are not worn. On the secular Saturday, to accommodate the CI position that in those locations Shabbos is in fact on Saturday, one should refrain from melacha, but otherwise, treat the day as a weekday, i.e. weekday Tefila and wear Tefilin.
If one visits Japan or New Zealand on Shabbos, the secular Saturday is the main day of Shabbos – Kiddush, Tefilla and keep Shabbos as usual. On Sunday, to accommodate the Chazon Ish’s position, one should refrain from melacha, but may daven the weekday davening and wear Tefilin.
Australia, even though most of the island lies east of the 125.2 meridian, because of the Gereira concept explained above, the entire country is pulled west over to the Asian side of the CI HDL resulting in Shabbos to be observed on the secular Saturday. (Why we apply Gereira to Australia and not to Alaska is beyond the scope of this article). Note: There are a number of great poskim who recommend observing Sunday as well and refrain from at least D’Oraisa melacha. However, this is not the common practice.
Crossing the HDL
What happens from a halachic perspective when one crosses the date line, when the day/date changes without one’s physically experiencing a change? One travels westward, from the U.S. to China, and crosses the HDL at 3 PM on a Monday afternoon moving the day forward to Tuesday afternoon 3PM, having already davened mincha while it was still Monday. Must he now daven Mincha for Tuesday, or do we consider it all one day as no day change was experienced. Must he now wear Tefilin for Tuesday as the next sunrise will not take place until Wednesday morning. What would he do if Monday was a fast day, 10 Teves. When one crosses the date line pushing the day forward to Tuesday at 3 PM, 11 Teves, may the fast be broken, as 11 Teves is not a fast day? Or must one wait until sunset to break a fast?
Flying in the opposite direction, where the day repeats itself, a new set of questions arise. One who flies from China to New York flies in an easterly direction on a Monday morning, is flying against the sun. During the 12 hour flight, 12 time zones are crossed and the day is pushed back. The result is that one who takes off from China on a Monday morning at 9 AM, will fly through the day, and some time in the afternoon, after having davened Monday mincha, the day flips back to Sunday afternoon. Upon reaching sunset must one daven Maariv. True, it just became night, but it is really Sunday night. He already davened Maariv Sunday night in China. When the traveler lands in New York on Monday morning at 10 AM, must he daven a Monday Shacharis. After all he already davened Monday morning in China. What about Tefilin? Krias Shma? Birchos Hashachar?
How would Halacha view a hypothetical trip from China to New York that took place on Pesach after having eaten Matza on the first night of Pesach. Following the seder, for pikuach nefesh reasons one flew that night to New York. Must he eat matza again as the day repeats itself? Or is matza a once a year event?
One who fasted on 10 Teves in Asia and flew eastward. The fast ended when it became dark. But as the sun rises again several hours later after having crossed the date line, 10 Teves repeats itself. Must he fast a second day?
One flew from China to New York on a Friday morning. At 6 PM local time, the sun sets. It is Shabbos. Two hours later, the HDL is crossed and Friday night becomes Thursday night. What halachos apply during the two hour Shabbos that he experienced.
A child born on Monday in New York crosses the date line in a westerly direction to China before the bris. Normally, the bris would take place on the following Monday which is the eighth day. But for this child, it is only his personal seventh day. Does the bris take place on Monday or on Tuesday?
What if the child flew in the opposite direction? Born in China on Monday and flew eastward to New York. The following Sunday is really this child’s eighth day even though the calendar says it is the seventh day.
Twin boys who travel around the globe in opposite directions a day before the bar mitzva. Is the one who saw an extra sunset a day older? Or do they celebrate the bar mitzva on the same day?
Would the same rules apply to one who sits shiva. Is it a personal count or a calendar count? How would a woman count shiva nekiyim?
These questions and more are dealt with extensively in Sefer Taarich Yisroel, a brief English summary of the sefer can be found in the appendix . Many of these questions are of a hypothetical nature and will not be dealt with in this article. Just note that with the exception of when Shabbos takes place, there is not a single question raised above that is agreed upon by all poskim. The focus of the next section will address common every-day questions that arise when traveling to and from the Far east from North America.
We raised a number of questions of how crossing the date line in either direction can affect halachic matters. As mentioned above, there is not a single area of halacha on which there is unanimous agreement.
Shabbos is clearly determined by one’s location. It has nothing to do with whether one experienced six or seven sunsets since the last Shabbos. One must observe Shabbos on the day that Halacha calls Shabbos. While there may be disagreement as to when Shabbos occurs in certain areas of the Pacific, – Japan, New Zealand, Hawaii, Alaska, all agree that one observes Shabbos on the calendar day. Shabbos is an astronomical phenomenon, not determined by a personal count.
On the other hand, how could a date determine when a child is eight days old ready for his bris? Surprising as it may seem, quite a few major poskim rule that the date is the determinant and it has nothing to do with the child’s personal count. These halachos are dealt with in Sefer Taarich Yisroel.
What I’d like to address are the everyday questions that arise during transpolar flights. Birchos Hashachar, Shma, Tefila, Shabbos, Sefiras Haomer, and Taanis. Interestingly, poskim treat each area of halacha on its own as they see different factors that trigger the obligation.
In broad strokes, there are two divergent opinions.
Opinion A– Day/Date
One can only daven once a day. The location determines the day/date, and that is the generator for the obligation. According to this view, if someone crossed the date line in a westerly direction pushing the day forward, even though he experienced no astronomical change, saw no sunrise or sunset, a new obligation is nevertheless born. Hence, if one left New York on a Monday morning and crossed the HDL (in all discussions we refer to the RYM HDL at 144.8W) at 3 PM local time after having already davened Monday Mincha, one is now obligated to daven Tuesday Mincha when the HDL is crossed. It is a new day. Similarly, one must don Tefilin as he has not yet worn Tefilin on Tuesday. The next Shacharis after landing will not take place until Wednesday morning.
On an easterly trip from China to the States, the day repeats itself when crossing the HDL. Hence, if one experienced a sunset, nightfall and daybreak, which are usually the astronomical events that generate the Tefila obligation, if one already said the Tefila for a particular day and the day is repeated, one does not have to daven again. One who takes the 10 AM flight that leaves China on Monday and lands in New York at 10 AM on Monday is therefore not obligated to daven Shacharis again.
Interestingly, according to this opinion, Birchos Hashachar may not be day sensitive but are rather prompted by one’s personal experience of a new day. They are blessings to thank Hashem each day for the benefits bestowed upon us; seeing, standing erect, etc. In the abovementioned flight where Monday repeats itself, since one did experience a night, Birchos Hashachar are required upon seeing a new daybreak.
Shma on the other hand has a third prompt. Shma is to be said Beshochbecha Uvekumecha, when daylight and nightfall are seen. Hence, in the abovementioned flight, Shma must be said whenever one sees nightfall or daybreak regardless of the day/date.
Although there is no unanimity within this opinion, as some poskim understand Birchos Hashachar to have the same triggers as Tefila, Sefer Taarich Yisroel ruled according to the consensus of poskim that follow this approach as mentioned above; that Tefila, Birchos Hashachar and Shma, all have different triggers.
Opinion B– The Experiential Trigger
One davens Shacharis in the morning, Mincha in the afternoon and Maariv at night regardless of day/date. You follow the sun. If one took the 10 AM Monday flight from China to New York, since one is flying eastward the traveler will experience a night and a sunset shortly before landing. During the flight, as he crosses the HDL the day is set back thereby repeating itself. Davening is determined by the personal experience, not the calendar. One must therefore daven Shacharis again on Monday morning in New York.
Similarly, when traveling westward and the HDL is crossed with the day being pushed forward midday, if one davened Mincha before crossing the HDL, no new Mincha is required after crossing the HDL even though the calendar calls it a new day. For this individual it is the same day.
It follows, that if one were to cross the dateline in an easterly direction on Rosh Chodesh, that Hallel and Musaf would be said twice.
Opinion A – Rav Moshe Feinstein, Rav Chaim Kanievsky, Rav Yechezkel Roth, Rav C.P. Sheinberg, Rav Ovadya Yosef.
Opinion B- Rav Elyashiv, Bezel Hachochma, Rav Yaakov Kaminetsky.
Option C- The compromise solution offered by Rabbi Taplin which attempts to meld both the above opinions will be explained after we summarize and review where we are up to at this point.
Summary
We have seen two overarching questions with regard to travel to the Far east
- Where is the Halachik Date Line.
The Chazon Ish places it at the 125.2E meridian. Where this meridian cuts through a landmass, the HDL hugs the coastline. Hence, the eastern portion of Korea (Seoul) which lies west of 125.2 at 126.9E is still considered west of the HDL. The Korean coastline would be the HDL. Similarly, eastern Siberia, east of 125.2E all the way until the Pacific coast is reached, would be considered west of the CI HDL.
Rav Yechiel Michel Tukatzinsky’s line at 144.8W, 180 degrees from Jerusalem, runs through eastern Alaska and south through the Pacific Ocean.
Rav Yisroel Taplin, author of Sefer Taarich Yisroel is of the opinion that since most poskim followed Rav Tukatzinsky, we use this as the primary HDL, while we do consider the CI HDL when dealing with D’Oraisa halachos. - What effect does crossing the Date line have on halacha
We cited two positions on this matter
Is the Day/Date the determinant as to how one deals with daily halacha obligations (Opinion A), or is the determining factor one’s personal experience of a new sunrise or sunset (Opinion B). Does the calendar trigger halachik obligations (Opinion A) or does the personal experience of the new day bring on the daily obligations (Opinion B).
The two opinions play out as follows:
On an East-West crossing of the HDL, the U.S. to China trip, the date line is crossed pushing the day/date forward. Therefore, Opinion A holds that if the date line is crossed in the afternoon after one already davened Mincha, as soon as the line is crossed one has a new obligation to daven Mincha even though for all intents and purposes it seems like the same day. Nothing transpired except for crossing some invisible longitudinal line. Opinion B on the other hand would say that since one is personally experiencing the same afternoon, no new obligation for Mincha is formed.
On the West-East crossing, from China to the U.S., the date line crossing pushes the day back and the day “repeats itself”. For instance, one crossed the date line on a Monday night. Several hours before landing the sun rises. Since the date line was crossed and Monday night at the place of crossing became Sunday night, the sunrise experienced before landing is Monday morning- again. Opinion A would say that all the daily obligations for Monday have already been performed and one’s personal experiencing a second sunrise for the same day is irrelevant. One need not daven Shacharis again. Opinion B on the other hand feels that the personal experience triggers obligations and one must daven again.
Both opinions are suggested by the greatest Poskim and it would seem that one has to choose one position over the other; both being perfectly legitimate. You can’t go wrong.
Rabbi Yisroel Taplin is reluctant to take a firm position on this matter and has suggested that there IS a way of satisfying both opinions . It may not be a perfect solution, but it is a close as you can get to one.
Saying Pesukei Dezimra (without Brachos) or Shma when in doubt pose no halachik problem whatsoever. Saying the Shmoneh Esrei when in doubt poses no question either. On is permitted to say a Tefilas Nedava at any time, and certainly when in doubt. Hence, when flying to China midday as in the case above, where Opinion A held that a new Tefila is obligatory while Opinion B said it is not, even Opinion B would have no objection to saying Shmoneh Esrei for Mincha as a Tefilas Nedava. Following this same line of reasoning, when flying in the opposite direction and the day/date repeats itself, Opinion B feels it is an obligation to daven again as the experience of a new day is the trigger, while Opinion A says that one need not daven a second time for the same day. However, even Opinion A has no objection to one’s saying Pesukei Dezimra, Shma, or davening Shmoneh Esrei again as Nedava.
In each case, where the two opinions disagree, there is no harm in following both opinions; On the westerly crossing Opinion A says the Tefila is obligatory and Opinion B would suggest that one may say it as Nedava. Conversely, on the return trip, Opinion B says Tefila is compulsory while Opinion A would agree that the Tefila may be said as Nedava.
The difficulty in finding a solution that will satisfy both opinions concerns the Brachos of Baruch She’amar, Yishtabach, and Birchos Krias Shma. If one says these Brachos when there is no obligation, one runs the risk of violating Bracha Levatala. Being that the abovementioned opinions are diametrically opposed, it is impossible to follow both completely.
It is here that Rabbi Taplin suggests a novel approach. There is a concept of saying a bracha with “Hirhur”, that is mentally without actually verbalizing the words, when one is faced with a safek, an uncertainty. Rabbi Taplin therefore suggests that one try to follow both opinions, and where a conflict arises with regard to Brachos, that they be said mentally, Hirhur.
Let’s apply this to the case mentioned above regarding the return trip where the date line is crossed in the middle of the night, the day/date is pushed backward, and a new sunrise is experienced. Opinion B would recommend saying the full davening when seeing sunrise. Opinion A would argue there is no obligation, but would agree that there is no harm in saying Pesukei Dezimra , Shma and Tefilas Nedava. With regard to the questionable Brachos, Baruch She’amar, Yishtabach, and Birchos Krias Shma, Rav Taplin recommends that these be said mentally, with Hirhur.
Granted, this solution can be confusing and may not be meant for all. It does however resolve a difficult problem when one is faced with having to choose between decisions made by the greatest of poskim.
In summary, when crossing the date line, one can take one of three options which should preferably be discussed with one’s individual rabbi or posek: follow Opinion A, Opinion B, or The Compromise Solution.
Fast Days and Sefiras Haomer
These two issues come up frequently with travelers as well.
When crossing the date line in a westerly direction, and the date gets pushed forward midday, there is disagreement among poskim as to whether the fast ends when the HDL is crossed, even according to Opinion A. One is flying to China on Asara B’teves and hits the HDL at 1 PM, pushing the date forward to 11 Teves. One could argue that it is no longer 10 Teves. On the other hand, once a fast day begins, it cannot end without a sunset. There are great poskim on each side of the aisle of this question. One should consult his own local posek. Insofar as this is a D’Rabanan fast, one may rely on lenient opinions. Rav Yisroel Taplin has not reached a firm psak and recommends taking a stringent position where possible, as there are some major contemporary poskim who do.. Recognizing that this position can add quite a few hours to the fast, in cases of hardship, a middle position can be taken whereby one may eat “pachos pachos mi’kishiur”, that is less than a Kezayis every 6 minutes. This compromise will satisfy all opinions. Where this is too difficult, one may rely on the lenient opinions.
When a fast day repeats itself in the case of an easterly date line crossing , it is hard to argue that one must repeat the fast and fast a second day (even though he ate in the night between these days), as one cannot observe a single day twice. If one ate Matza on the seder night in China, and then, theoretically flew to New York and came in time for a Pesach seder again as the day flips back, all agree that he need not east Matza again. Why would a taanis be more stringent? On the other hand, there is a concept of joining the community in their time of pain. If the community is fasting, one may not ignore this fast. Again, great poskim on both sides of the argument and one should consult his own posek.
With regard to Sefiras Haomer, Taarich Yisroel recommends counting the day in which you find yourself. Flying westbound on a Monday afternoon day 11 of sefira, as the HDL is crossed and the day/date is pushed forward, Monday day 11 becomes Tuesday day 12, one would count day 12 without a bracha, and continue counting with a bracha day 13 when time to daven Maariv in China arrives.
On the return trip, when the day repeats itself, one should count the local day. If it a repeat of the prior day, one may count again without a bracha, and then continue on with a bracha. On the following nights.
In Flight to the Far East
Most flights today take a transpolar route. However, before seeing how the two opinions play out on transpolar flights, it is important to get a grasp of the differences of opinion on non-transpolar flights, those flown prior to 2005.
There were 2 routes from New York to Beijing. One can fly west with a stopover in Anchorage. Or one can take an easterly route with a stopover in Frankfurt. The westerly route which crosses the date line is about 1000 miles shorter than the easterly route which does not cross the date line. Most travelers until the year 2005 flew the westerly route.
Before applying the halacha to non-stop flights, let’s go through the exercise of studying both routes as they existed prior to 2005, where a stopover was required. New York to Beijing via Frankfurt and NY to Beijing via Anchorage.
The easterly route leaves New York on Monday at 9 PM, arrives Frankfurt 8 hours later, NY time Tuesday 5 AM, local Frankfurt time 11 AM. 6 time zones between NY and Frankfurt. When one saw sunrise a few hours before landing, he had to daven Tuesday Shacharis. The plane refuels and leaves Frankfurt at 1 PM. Time for Tuesday Mincha. The 12 hour flight to Beijing will arrive at 1 AM Frankfurt time which is 8 AM Beijing time. Another 7 time zones were crossed. During this flight a sunset was experienced and the traveler davened Tuesday night Maariv. Upon landing in Beijing at 8 AM, he must now daven Wednesday Shacharis. The Date line is not crossed.
The rule of thumb on this is to simply follow the sun. Both Opinion A and Opinion B would agree. On the westerly route, this traveler left NY on Monday night at 9 PM. Arrived 8 hours later in Anchorage at Tuesday 5 AM NY time which is 1 AM Tuesday Anchorage time. Anchorage is 4 hours behind NY, so although he flew for 8 hours, by subtracting 4 time zones the local time is set back. Although one left at 9 PM and it is now 1 AM, interestingly, the RYM HDL had been crossed about ½ hour before landing in Anchorage. Remember, Anchorage is located at 149.9W, about 5 degrees west of the HDL.
Halachically, it is Tuesday night ( that is, early Wednesday morning – even though according to the secular calendar the day has not yet changed, and it won’t until the IDL is crossed. The secular community does not recognize the HDL)! Opinion A would require thatTuesday night Maariv be said again. Opinion B would argue, that since it is the same night as he left NY, no Tefila is required.
The plane refuels and takes off at Tuesday 3 AM (Halachically Wednesday, by secular time it is still Tuesday) local time, or 7 AM NY time. Still dark outside. The plane continues west, crossing time zones that lose time, and lands 12 hours later at 7 PM Tuesday NY, 5 PM Tuesday Anchorage time, which is 8 AM Wednesday China time. From the traveler’s perspective, he took off at 3 AM and landed at 8 AM with almost the entire flight except for the last 2 hours taking place at night. His watch moves only 5 hours while losing 7 hours by flying west crossing 7 time zones. But somehow, rather than local time 8 AM Tuesday, it is 8 AM Wednesday. The date line pushed the day forward. Beijing is 17 hours ahead of Anchorage rather than 7 hours behind.
Halachically what happened?
Opinion B sees it as follows. Anchorage to Beijing was a night flight that landed at 8 AM. The day is irrelevant. When he lands in Beijing he davens Shacharis. What happened to the entire Tuesday? Opinion B is not concerned. Davening and daily mitzvos are determined by one’s experiencing a new day.
Opinion A has a very different take. The HDL pushed the day forward before reaching Anchorage. Hence the traveler davened Tuesday night Maariv in Anchorage as mentioned above. When the plane took off from Anchorage on Tuesday at 3 AM (Halacha time 3 AM Wednesday), it flew west and hit the IDL about 2 hours into the flight where secular time catches up to halachic time local time. It is now Wednesday 4 AM. When he lands in Beijing on Wednesday at 8 AM he must daven Shacharis.
The return trip is a bit more complicated.
Takeoff from Beijing on Monday at 8 AM. 12 hours to Anchorage lands at Beijing time 8 PM Monday, local Anchorage time 3 AM Monday. The plane refuels, takes off at 5 AM Monday local time and lands 8 hours later in NY at 1 PM Monday local time which is Monday 5 PM NY time. This plane that took off on Monday morning at 8 AM landed 22 hours later in New York at 5 PM, a movement of only 9 hours on the clock.
Let’s study what happened halachically
Opinion B follows the sun. Hence, on the first leg of this trip, Beijing to Anchorage, as the plane travels easterly toward the sun. It will reach time for Mincha about 4 hours into the flight. When the sun sets 5 hours later time for Maariv. The second leg starts at 5 AM local time. An hour after takeoff the sun rises. Time for Shacharis. When the plane lands in NY at 5 PM or a few hours before then, time for Mincha. Quite simple. Follow the sun.
Opinion A looks at this trip very differently. It takes the calendar day into account. On this trip, Opinion A would recommend the same procedures on leg 1 as Opinion B. Monday Shacharis before takeoff. Monday Mincha 4 hours later. Monday night Maariv after the sun sets. However, leg 2 is quite different. About an hour after takeoff from Anchorage, the plane hits the HDL over eastern Alaska at 144.8W. The day is pushed back. So that when the sun rises, it is MONDAY sunrise. This is this traveler’s second Monday. Since he already davened Shacharis for Monday, Shacharis is not repeated. Ditto for Monday Mincha and Monday night Maariv. He does not daven again until Tuesday morning in NY.
The exceptions to these rules are Birchos Hashachar and Krias Shma. For although the day is repeated, the triggers for these are not day sensitive but are the obligation is rather generated by one’s personal experience. Hence Birchos Hashachar are said when he sees the second Monday sunrise. Similarly, Shma is said on this second Sunday morning and evening as the prompts for Shma relates to morning and evening, Beshochbecha Uvekumecha.
One word of caution with regard to Birchos Hashachar. Even though a new sunrise may trigger the obligation, if the traveler did not sleep since the last night, there are a number of brachos that are questionable if they should be said; similar to the questions we experience every Shavuos morning.
Lastly, as mentioned above, Option C- the compromise solution, should be considered where appropriate.
Polar Travel Routes
Travel to the Far East from the United States has taken on an entirely new character since the publication of The Dateline in Halach in 1999. Much of what was written at that time with regard to how mitzvos are to be observed during the flight, has become obsolete with the advent of the adoption of the transpolar route by the airline industry.
Routine transpolar flight became possible after the end of the cold war, when the U.S. and Russia adopted new policies of allowing commercial flights over each other’s territory, and with the development of planes like the Boeing 747-400 and Airbus A340, with ranges of about 9,000 nautical miles.
Transpolar flight reduces flight times significantly, transpolar flights are smoother with less turbulence in the polar region, more cost effective, and environmentally preferred because of reduced fuel emissions. In 1999 United Airlines flew 12 polar demo flights. By 2006 the total for all airline polar flights exceeded 5000.
Travel via transpolar route may affect halachik practice during the flight. Prior to the introduction of the transpolar route, most flights from New York to the Far East stopped in Anchorage for refueling and a crew change. Anchorage is in the sub Arctic region. Today however, since part of the flight takes us through the polar region, where times zones are so compact and shifts in daylight hours between summer and winter are so extreme, there is no simple one-size-fits-all method of approaching halachic issues. Each case must be individually studied. However, in order to gain an appreciation for what may arise, a basic understanding of what transpires from a geographic/halachik perspective during such trips is in order.
Latitude
Latitude, otherwise known as parallels, are lines that run on the map horizontally. The Equator is the 0 parallel, while the North Pole is at 90 degrees north. Each degree in latitude measures about 70 miles, so the distance between the Equator and the Pole is approximately 70 X 90 = 6300 miles. Latitude measurements of some common cities: Miami (26 North), Jerusalem (32N), New York (40N), London (51N), Anchorage (61N), Beijing (40N), Hong Kong (22N).
The latitude and the time of year determine the time of sunrise and sunset, the length of the day at each location in the world. The further one gets from the Equator, the wider the range of the gap between sunrise and sunset
Twilight
In the same way that latitude affects the length of day, the amount of time between sunset and darkness, twilight or Bein Hasehemashos, varies greatly as well.
The U.S. Naval Observatory divides twilight into 3 segments.
Civil Twilight: the time at which the sun is 6 degrees below the horizon. At this time, there is enough light for objects to be clearly distinguishable and that outdoor activities can commence (dawn) or end (dusk) without artificial illumination. Civil twilight is the definition of twilight most widely used by the general public.
Nautical Twilight: the time when the center of the sun is 12 degrees below the horizon, and only general or vague outlines of objects are visible. During the evening this is when it becomes too difficult to perceive the horizon, and in the morning this is the point when the horizon becomes distinguishable. This term goes back to the days when sailing ships navigated by using the stars.
Astronomical Twilight: the time at which the sun is 18 degrees below the horizon. It is that point in time at which the sun starts lightening the sky. Prior to this time during the morning, the sky is completely dark. During the evening, this is the point where the sky completely turns dark.
The Halachic definition of twilight is difficult to pin down. In broad strokes, some opine that the time of Alos Hashacha, daybreak, or Tzeis Hakochavim, nightfall is a fixed number of 72 minutes before or after sunrise or sunset respectively, regardless of location or date. Others feel that the amount of darkness perceived, defines Alos and Tzeis. For a study of this subjectI refer you to an excellent book recently published, Dvar Yom by Rabbi Dovid Braunfeld. The reason why I even broach this issue, is because when one is in flight, the sky is in a twilight state for much longer periods than we experience at sea level, especially at extreme latitudes. Trying to figure out just what one sees can be a challenge.
The Arctic Region
As is evident from the above, higher latitudes engender extreme variances in day length. In Iceland, which is only about 2 degrees below the Arctic Circle, the day length can be as short as 4 hours in December, or as long as 21 hours in June. As you go above the Arctic Circle (66.5N), there are days during the summer when there is no sunset at all, and days during the winter when there is no sunrise. The higher the latitude, the greater the number of days that fall into this category. At the North Pole, the sun rises in March and sets in September. Day length is 180 days. At the 80th parallel, there are about 130 days of daylight. At the 70th parallel the number of daylight-only days is about 70.
The inverse is true during the winter months, from September to March. There is no daylight for the equal amount of days at each respective latitude point.
Without time demarcations of sunrise and sunset, it is difficult to determine zmanim. It is beyond the scope of this essay to address any issues in this region. Insofar as much of the transpolar trips take place in this region, it is important to get a basic understanding of just what one sees when looking out of the window. It could be midnight and the sun could be high in the sky, or it could be noon and the stars are shining bright, all dependent on the date and the latitude.
Flight Paths, Time Zones, and Halacha
The shortest distance between two points is a straight line.
When planning a flight path for air travel, the navigator must take factors other than mileage into account, i.e. weather conditions, air traffic control, etc. There may be several different routes for pilots to choose when plotting their flight plans. During certain times of the year a pilot may choose a more northerly route, at other times a more southerly route. The guiding principle is to reach the destination in the shortest amount of time while trying to conserve fuel as much as possible.
Polar Routes
Having studied above what happens during a relatively simple flight from New York to Beijing via Frankfurt or Anchorage, where the whole flight takes place in the temperate zones, we can now embark on a far more complex study of polar trips, as we investigate the potential halachic issues as we pass through extreme geographic zones.
Longitude lines converge at the Poles. While the distance between each longitude degree measures about 70 miles at the Equator, as you move toward the Poles, longitudinal degrees get smaller and smaller.
| Latitude | Miles between each longitude degree | |
| 0 | Equator | 70 |
| 40 | New York | 53 |
| 50 | London | 43 |
| 60 | Anchorage | 34 |
| 70 | 23 | |
| 80 | 11 | |
| 85 | 5 | |
| 88 | 2 |
In practical terms, a plane traveling at 500 mph from East to West at the 40th parallel, a New York to California flight, will cross only about 10 longitude degrees, or about 2/3 of a time zone in each hour. The 2500 mile distance translates into approximately 48 degrees or 3 times zones.
On the other hand, if the flight path were within 300 miles of the North pole (the flight path of many flights to the Far East), that would mean that a plane traveling at 500 mph at the 85th parallel, would cross 100 longitude degrees or about 7 time zones in a single hour!
This could have possible halachic ramifications. Because of the halachic complexities of dealing with the polar region, in our study we will for all intents and purposes suspend halachos affected by time in these extreme circumstances, But an understanding of what transpires during the flight, and the ramifications of these changes upon re-entry into a more “normal” environment is important.
Polar East or Polar West
We think of China being to our west, that is to the left on a flat map of the world. However, if you look at the world from the North Pole, we could draw a straight line from New York to Beijing or Hong Kong that goes north to the pole and then south from the pole.
If you flew directly north from New York at the 74W meridian, after you crossed the pole you would end up at the 106E meridian. (Beijing and Hong Kong at about 113E). So the most direct route would be to go directly north with only a slight nudge to the west to compensate for those few degrees.
There are many factors that determine a pilot’s particular route; wind speeds, weather conditions, etc. At times the pilot may choose to fly just west of the pole, while at other times he may choose to fly east of the Pole.
Stand above a globe looking down at the North pole. If you drew an almost straight line from NY to Beijing just to the left of the pole (west), you would cross the Anti-meridian, or the IDL. Draw an almost parallel line but this time drag it just to the right of the Pole (east), and you never cross the date line at all. The HDL of both CI and RYM be crossed as well but at slightly different times in flight. We use the RYM HDL at 144.8 in this section for halachic study.
While in reality these two routes are quite close to each other, within a few hundred miles, as you look at these flight paths on a flat map of the world, the western route which crosses the date line looks like it is flying high over Alaska, the Bering Straits and Eastern Siberia.
The easterly route looks like it is flying over Northern Europe, Finland, and Russia.The screens on planes showing your location during flight, reflect this reality but from a different perspective. The maps that are shown on the planes do not show a polar view but rather a flat view. On some flights the map shows you flying over Alaska, while on other flights to the same location, the map may show that you are flying over Finland.
You take off and land at the same time. On the easterly route you are flying east through many time zones with the clock racing forward, so that local time at destination (Hong Kong) after a 16 hour flight, will be 28 clock hours after takeoff. On the westerly route, your time falls back 12 hours and then fast forwards 24 hours upon crossing the date line, netting you the same 28 clock hours.
The Transpolar Flight- New York to China
When boarding a plane to the Far East, there is no way to know in advance what route the pilot might take; Northwest over Alaska and Siberia, or Northeast over Scandinavia and Russia. While most flights take the NW route, during certain times of the year, the NE route is quite popular. If you follow the route of the plane of the screens, you can usually determine the flight path within the first hour or two. The plane will fly either due north or slightly west in which case it will be a NE route. A slight turn to the east is indicative of the NE route.
The Northwest route (NW) leaves NY flying almost directly north toward the pole. During the first 5 hours of the flight, the longitude veers ever so slightly westward, and you have moved only one time zone backward, from Eastern Standard Time (GMT -5) to Central Time (GMT -6). During this time, when you are about 4 hours into the flight, the Arctic Circle is crossed. You will remain in the Arctic region until the 10th hour of your flight, when you re-enter the sub-Arctic region.
If we so-to-speak stop the clock when you enter the Arctic region, and restart it 6 hours later when you re-enter the sub-Arctic, where conventional halachic zmanim come into play, your clock will have moved forward by about 21 hours. More correctly, it will have moved backward in time by 3 hours and catapulted 24 hours forward as you cross the date line, resulting in a net gain of 21 hours.
The Northeast route (NE) enters the Arctic zone during hour 4 as well and stays there for the next 5 hours. If we stop the clock when we enter the region and restart it 5 hours later upon re-entry into the sub-Arctic, you will have fast forwarded the clock by 9 time zones, and the net result will be a net gain of about 18 hours.
It is hard to figure out where you are or what the local time is, or even in what day of the week you find yourself. Without this knowledge it is not easy at all to know when to daven. Unless you know where you are and the LOCAL time, it is impossible to decide how to daven according to both opinions, A and B. There are times of the year, that you might be flying close to the North Pole and it will be light outside at midnight local time. During the winter, the entire afternoon might be dark.
The Appendix includes a chart of a typical Northeast and Northwest flight from New York to Hong Kong. It shows the time at point of departure (time on your watch) as well as the local time. Flight paths can vary considerably, but the charts are a good guide as to where you are when. Using these charts in conjunction with a visual peak outside to see the sun’s position, one can come as close as possible to make an intelligent decision.
If you follow the psak of Opinion A, pay careful attention to the longitude column to see about when you will be crossing the HDL at 144.8W, usually about 6 hours into the flight. Opinion B is really not concerned with crossing the date line. Remember, if the flight does take the Northeast route, the HDL is not crossed.
Flight Paths and Times Zones In Flight
Following is an illustration of how to use the chart (not recommended unless you’ve made the trip a few times).
The Northeast (NE) flight that departs New York at 1 AM Monday (Sunday night) will hit daylight by the end of hour 4. NY time is 5 AM but local time is 6 AM Monday. 3 hours later, when it is 8 AM NY time at the point of origin, the local time will be 3 PM, time for Mincha. In these 7 hours of flight time, time has advanced by 11 time zones. Only 2 hours later, 10 AM at point of origin, local time is 10 PM, time for Maariv. By the time the plane lands at 5 AM, it is almost time for Tuesday Shacharis of Tuesday morning. There is no difference between Opinion A and Opinion B.
The Northwest (NW) flight looks quite different. By the end of hour 5, local time is 6 AM and one can daven Shacharis. But here the times zones go haywire. By the end of hour 6, when the time in New York at point of origin is 7 AM, local time is 4 AM. 3 times zones crossed in just the past hour. During the next hour 5 more time zones are crossed pushing time backward, but the date line is crossed pushing the date forward. When it is 8 AM in NY Monday morning, local time is midnight Tuesday morning. Local time is ahead of point of origin, not behind it even though you are flying west. Over the next 8 hours, the local time moves slowly to land at 5 AM
Let us analyze what happened here halachically. The entire flight took place at night except for a brief window at around hour 5 when the sun appeared for just a little while. Enough time to daven Shacharis. The clock however never hit a local time where one could daven Mincha. What happens at hour 7 when the sun disappears and night is seen again? Opinion A would argue, that since the HDL is crossed and the day is pushed forward, Sunday night became Monday night, a new Tefila for Maariv is required. Opinion B on the other would argue that the Sun’s disappearance is not a real sunset for it is caused by latitude changes rather than longitude, no Maariv is required.
This is but one scenario. Realistically, during the summer months it is bright light throughout the night when looking out the window. And during the winter, it can be dark at noon local time. Furthermore, at extreme latitudes, sunset at an altitude of 35,000 feet can precede sunset at sea level by as much as 2 hours. Halacha recognizes sea level zmanim. I therefore caution you not to use these charts unless you are quite experienced with these flights and know how to make the necessary adjustments.
Flight paths vary by season. It is recommended that you inquire about your flight before flying.
The China to New York Flight
The China to New York flight will cross the date line.
The Hong Kong flight hits the RYM HDL about 9 hours after takeoff, the Shanghai flight after about 8 hours, and the Beijing flight will reach the HDL about 7-1/2 hours after takeoff. When it reaches the HDL, the day is pushed back, Tuesday becomes Monday. The day repeats itself.
Opinion B follows the sun. A flight that left Hong Kong on Monday at 10 AM HK time will reach the HDL 9 hours later at about 7 PM HK time. Local time is 2 AM. That is 2 AM Monday as the day was pushed back. The sun would have set by the end of hour 6 where local time was 7 PM. If the traveler davened Maariv shortly after dark, when he sees daylight by the end of hour 11 when local time is Monday 6 AM he will daven Shacharis. The fact that he already davened Monday morning in Hong Kong is irrelevant. As far as the traveler is concerned, he saw a sunrise and that triggers a Tefilas Shacharis. After landing in NY at noon, when the time for mincha arrives he davens Mincha even though he davened a Monday Mincha on the pane.
Opinion A looks at it very differently. The day/date is all important. Hence, if our traveler davened Monday Shacharis in Hong Kong, Monday Mincha and Monday night Maariv on the plane, he does not daven again until Tuesday morning. (with the exception of Birchos Hashachar and Shma where the obligation is not necessarily day /date sensitive.
The Friday Flight
There is a popular flight that leaves Hong Kong at 9 AM on Friday (local time in NY Thursday 8 PM) which arrives in New York at 11 AM same day, Friday. During this flight, as you fly east, the hours advance quickly and you will experience a sunset, a full night and a sunrise. You will fly for 15 hours but the clock will advance only 2 hours. 11 time zones are crossed pushing time ahead by 11 hours, but as the HDL is crossed, the day is pushed back by 24 hours. A net change of 13 hours as Hong Kong is 13 hours ahead of New York.
By approximately hour 9, the RYM HDL is crossed. Friday becomes Thursday. If the HDL is reached before sunset, Shabbos begins. However, immediately upon crossing the HDL, the day becomes Thursday night. As you can see on the charts, with a 9 AM departure from Hong Kong, the HDL is crossed approximately 9 hours later when local time is 12 AM. However, the sun set by the end of hour 6 where local time was 6 PM. From hour 6 to hour 9 the traveler is in the Shabbos zone. One must refrain from melacha, be careful not to move the seat or use the restroom as these actions entail doing a melacha. And it is recommended that muktza be removed from the pockets. Since one did not say Kiddush, one may not eat. While there are differing opinions as to whether kiddush should be recited, the Taarich Yisroel is of the opinion not to recite Kiddush. When the HDL is crossed, it becomes Thursday night and one may resume weekday activities.
Note however, that the time of the year of this travel is a critical factor as well. Let us look at the 2 AM flight from Hong Kong. The HDL is reached by the end of hour 9 where local time is 5 PM. If one takes this flight in June, when sunset is at 8 PM, the HDL is reached before sunset, hence Friday 5 PM becomes Thursday 6 PM. When the sun sets an hour later, it is Thursday night. On the other hand, if this flight is taken in December when sunset it at 4 PM, the sun will set about an hour before reaching the HDL in which case Shabbos must be kept for an hour.
A frequently asked question, should one avoid the Friday flight if it will raise Shabbos issues as mentioned above. The short answer is yes. However, if not taking this flight because of the minor inconveniences will mean that one spend Shabbos in the Far East, the answer is absolutely no- do not avoid taking the flight. Besides the advantage of spending Shabbos with family which is of great importance, the challenges posed by staying in Far East hotels, most of which today outfitted with “smart” rooms that electronically manage your stay to make your visit as comfortable as possible, from auto key locks, to auto lights, a/d, faucets, etc. are often overwhelming and almost impossible to avoid. It is therefore recommended that if the choice is between the Friday flight or staying over Shabbos, take the Friday flight.
Conclusions
Location of the date line is a subject that has intrigued poskim for the last 1000 years, though it has truly come to the forefront, halacha lemaaseh, only in this last century
In a nutshell, although many possible locations have been suggested, the three dominant opinions are those of Rav Tukatzinsky – 180 degrees from Jerusalem at 144.8W, the Chazon Ish, 90 degrees east of Jerusalem at 125.2E (with minor Gereira adjustments) and Rav Isser Zalman Meltzer who accepts the IDL. Most poskim follow the first opinion and it is that opinion that we’ve adopted. However, we do recommend that the second opinion of the Chazon Ish be considered when dealing with D’oraisa halachos. Those who follow the opinion that the IDL is to be used have support among some authorities.
With regard to what effect crossing the date line has on halacha, we presented what we referred to as Opinion A – halachos change as one crosses the line, and Opinion B – that halacha is linked to one’s personal experience. A third opinion that we call the compromise solution, one that attempts to accommodate all opinions was suggested as well. Insofar as all opinions are supported by the greatest poskim of the past generation, one should seek guidance from one’s own halachik authority.
Appendices
Appendix A is a series of charts that offer the traveler a graphic picture of typical flights that can act as a guide as to how to prepare halachically for the flight.
Location and Time Charts
How to use the charts
There are 2 sets of typical flight paths from New York to Hong Kong (Northwest and Northeast) and 2 flight paths from Hong Kong to New York. Each flight path (Northern and Southern).
Each flight path has 24 start times. Start time means takeoff, not when you leave the gate. The chart shows your approximate location at each hour of the flight with the time at point of departure, the time on your watch, and local time taking into account time zone changes.
The charts can be a bit confusing even for the seasoned traveler, and I welcome inquiries before your flights so that you can prepare accordingly
For the NY to China trip, we chose a typical Northwest route and typical Northeast route, marked NW and NE respectively. Find the chart that relates to your time of departure and you can see approximately where you are, what is the time at point of departure (time on your watch), and local time. The times are approximate as no two flights are identical. Some flights fly within 2 degrees of the pole, while others may not fly higher than the 70th latitude, 20 degrees south of the pole. The charts are merely meant as a guide.
On the return flight, Hong Kong to New York, there are two main flight paths. One is more northerly, flying just south of Alaska, the southern route flies in a straighter line across the Pacific. There is not much of a difference between the routes, but as you follow your flight on the plane monitor and compare to the charts, decisions on when to daven are made easier.
Times for sunrise and sunset vary widely by latitude and season. Around the spring and fall equinox, times for sunrise and sunset all over the world are the same. The sunrisesunset.com website can customize a calendar for any location any day of the year, but getting it right can be a bit complicated.
Note, Halacha recognizes zmanim at sea level. Times of sunrise and sunset at sea level can vary widely from the times at 35,000 feet. While a visual look out the window may indicate that the sun has not yet set, it is very possible that at sea level, the sun has already set. This is especially important for the Friday flight. Time of year, latitude and altitude can play a major role in these discrepancies. The zmanim on the charts are meant to be a general a guide. When planning a trip, I recommend that you contact me by sending your itinerary, so that I can offer some guidance accordingly.
Contact:
Email: stropper@codaresources.com
Text/Whatsapp: 917-763-1019
Kitzur Taarich Yisroel
Appendix B is a copy of the original book entitles “The Dateline in Halacha” that i published in 1999. It offers some background and source material for those interested in a deeper understanding. The book was originally published as a brief English synopsis of Rav Yisroel Taplin’s sefer on the subject, “Taarich Yisroel”.