In the Parsha Code Removed from KosherJava Zmanim Calendar API article posted two years ago, I documented the removal of the the parsha code from the KosherJava Zmanim API due to licensing issues. I would like to announce that thanks to Yechiel Paricher, the zmanim library now supports a clean LGPL implementation. Yechiel’s Jan 17, 2019 pull request that was a port of his C libzmanim code, was finally merged on August 22nd, and over the past day, the old formatting code for parshiyos was restored after being changed to work with the new code. The new code not only restores the old functionality, but adds support for the special parshiyos of Shekalim, Zachor, Parah and Hachodesh. It also added support for Shabbos Mevorchim and Machar Chodesh.
With the start of the new year 5780, I have been asked the following question numerous times. What is the proper Hebrew spelling of the Jewish year 5780 (2019/2020). Is it spelled תש”פ or תש”ף? This is the first time in 30 years that we have this “burning” question, with the previous one being 5750 (1989/1990) תש”נ or תש”ן. The question arises when the Hebrew spelling of the Jewish year ends with a Hebrew final form (also known as end, “ende” or straight (versus bent)) letter of מנצפ”ך. This happens in years ending with a 20, 40, 50, 80 or 90. According to the Academy of the Hebrew Language’s article שנת תש”ף regarding the spelling of the year, the final form תש”ף is the correct spelling. However, things are not that simple. The excellent 1,700+ page calendar לוח דבר בעתו / Luach Davar Be’ito published annually by Rabbi Mordechai Genut, straddles this by showing one form on the front cover and the other on the spine. In the introduction, Rabbi Genut writes:
ישבנו על המדוכה כיצד לכתוב תש״ף או תש״פ. כדי לרצות בעלי 2 הדעות, נקטנו (כאשר נקטנו בלוח ה׳תש״ן) שבשער הכריכה יכתב ה׳תש״פ ואילו בכריכת הגב יכתב ה׳תש״ף.
In the calendar he published an 11 page essay on the subject by Rabbi Yaakov Matalon who provides the following reasons to use the תש”פ version:
- ראשי תיבות or Hebrew abbreviations only end with a final form letter if the abbreviation is typically read as a word such as רמב״ם ,רמב״ן and רי״ף. Abbreviations such as יוה״כ that are read as יום הכיפורים are always spelled ending in a non-final form letter. The Academy of the Hebrew Language reads the year as the proper word תָּשָׁ״ף, while many (most) disagree and read it as תאו-שין-פא.
- The abbreviated year is not an abbreviation at all, but a number in its Hebrew format, and final form letters do not belong at the end of a number. This has been the tradition in writing and publishing Jewish books, where the non-final form spelling of page and chapter numbers has traditionally been used. This can be seen in the Talmud, Shulchan Aruch, Tehilim and other sefarim. There have been exceptions to this rule, but they are indeed exceptions. The same tradition is in place on most Jewish monuments.
- In some cases the final form מנצפ”ך letters are considered to have a different numerical value. See the Sefer Haaruch on the אטב״ח entry (the Atbach / אטב״ח cipher should not be confused with the אתב”ש / Atbash cipher) and the Maharsha’s explanation on Rashi in Sukka 52b.
- For kabbalistic reasons the Sefer Chassidim in chapter 1154 mentions that the end form of the letter ף is avoided where possible in tefilah (מוסף is an unavoidable exception). The Sefer Harokeach mentions the same concept in chapter 337 regarding the lack of any ף in Birkas Hamazon. This would apply to this year that ends in an 80, but not the other 4 examples every century.
Rabbi Matalon ends with:
מסקנתנו היא, שמִּבֵּין שני האֳפנים, עדיף לכתוב באות רגילה, לא-סופית: תש״פ, תש״צ. מכּל השיקולים נמצא שזה האופן העדיף. מצד שני, נראה שאין מקום לטענה שהכותב באות-סופית, תש״ף, תש״ץ וכדומה, טועה הוא. אופן כתיבה זה, למרות חסרונותיו, מקובל אצל רבים, ואין מי שרואה בו טעות.
In short, neither is incorrect, but the better of the two is the non-final form תש”פ.
Formatting the Year in the KosherJava Zmanim API
The HebrewDateFormatter class in the KosherJava zmanim library coded years ago produced the final form of תש״ף (with the exception of single character years such as the year 5050). This logic was included in all ports that I am aware of. With a recent commit, the option for formatting years ending in מנצפ״ך was added, and the default changed to produce the non-final form version of תש”פ. Detailed information can be seen in the HebrewDateFormatter API documentation.
Determining zmanim times while on an airline flight is rather complex compared to calculating it for a fixed location. Some of the complexity involves:
- Where you are currently located
- Your Speed
- Direction of travel / flightpath
The above 3 variables impact the calculation of what the zmanim are in your current location and where you will likely be when various zmanim are met.
Surprisingly, the hardest part is figuring out your current location. The shortest point between 2 points on the globe is the great circle route. Though it is the shortest path, airliners rarely fly this way. To take advantage of prevailing winds such as the Gulf Stream, or to avoid bad weather, airlines often fly much longer routes and as a passenger you often do not know exactly where you are.
Yes, the airline shows you a nice location map, but getting your exact coordinates from the map is not something that they usually supply. From a practical perspective, many people on domestic and short international flights will manage to figure out davening times by themselves. As a general rule of thumb, it is time for Shacharis when the sun rises and time for Maariv when it gets dark. Please keep in mind that most poskim are of the opinion that we use zmanim at sea level elevation, or ground level, and not the 37,000 foot elevation of the flight. This elevation results in a difference of approximately 20 minutes in sunrise and sunset times. Not sure when Mincha time is? Wait until shortly before sunset. Just keep in mind that when flying due east (such as a flight from NY to Israel), you are flying in the opposite direction as the sun and the time for davening is compressed. While you may expect sof zman krias shema to be 1/4 of the way into the day, in this case the davening window is compressed into a much shorter time. The real complexity is in flights that cross the halachic dateline, polar flights and to a lesser degree, cross-Atlantic and Pacific flights. This article will not delve into the halacha of in-flight zmanim, but solely on the technical aspects of figuring out the zmanim times.
Using your phone’s GPS to identify your in-flight location, or even a standalone GPS device will usually not work once you are away from cell towers (where your GPS no longer has the assistance of A-GPS). GPS signals are very weak and your GPS receiver typically does not have an antenna strong enough to pick up the signals in an aluminum or even newer carbon fiber composite airplane like the Airbus A350 and Boeing 787. To receive a signal, an external GPS receiver is usually required and assuming that you can get a signal (it helps if the external receiver is placed by a window), we can proceed. Note that while you would expect that the CFRP body of a Boeing 787 would allow for a much stronger signal than aluminum airliners, the graphite (and probably other materials) in the 787 CFRP in conjunction with the electrochromic windows on the 787, completely block GPS signals. It is this shielding as opposed to GPS jamming that blocks signals on El-Al 787s. In my testing with an external GPS device designed for aviation such as the Dual XGPS 160, the composite A350 and 787 both do not allow enough GPS signal through for a GPS receiver to provide a location fix. It may be surprising that it is easier to receive the weak GPS signal in an aluminum fuselage than a composite one, but keep in mind that carbon fiber is an excellent electrical conductor. Carbon fiber was used as the filament in Thomas Edison’s early light bulbs and does not let RF signals through and effectively acts as a Faraday cage. If you are able to receive a GPS signal, you can accurately calculate zmanim for your current location using tools such as the KosherJava zmanim map. Just change the latitude and longitude to what you see in your GPS in the URL https://kosherjava.com/maps/zmanim3.html?lat=75.74&lng=-63.22&zoom=3. While not an ideal solution, it does work. The same works for the rare airlines whose maps do show accurate GPS coordinates. Please note that Wi-Fi based geolocation will not work on your flight (in my testing it gave the location of the service provider headquarters).
Precalculated Flight Paths
Another way to figure out where you are located when in the air is via a precalculated flight path. This allows programs such as the Chai Tables Chai Air Times program for Windows and Android to work. However, they just calculate a great circle route between the origination and destination locations, something that is not very accurate. Currently MyZmanim’s Inflight charts are the most practical. These charts calculate the average path of the 5 previous flights in an attempt to better estimate your flight path and provide precalculated charts based on the time you take off. While this solution is currently the best that I am aware of, there are a number of issues with it. For one, much of the flight path over the oceans and Arctic that are provided by services such as FlightAware and others (that are used by MyZmanim) are just educated guesses for cross oceanic or Polar flights, since there are no ADS-B receivers in much of this area. As a matter of fact, this terrestrial ADS-B receiver free area comprises 75% of the globe. Even if the previous flight paths were accurate, your current flight may be very different. Flights such as the Cathay Pacific flights from the NY area to Hong Kong fly either east or west depending on wind conditions. MyZmanim deals with this scenario by providing both east and west maps (based on the in-flight map you would use one or the other) and indicating the portion of a flight-path that is unknown, but this is a warning that does nothing to help you accurately calculate zmanim.
Every airliner broadcasts its position, heading, altitude and speed using ADS-B. A technical user can bring an ADS-B-receiver with him on the flight and use it to retrieve the current information on his flight. This would work even when there are no ground based ADS-B receivers. This is something costly and beyond the technical ability of the vast majority of flyers.
Due to issues in tracking flights that came to light with the disappearance of Malaysia Airlines Flight 370, satellite based ADS-B tracking is rolling out and will be mandated. This will make it much easier for services such as MyZmanim to provide more accurate pre-flight estimates, since services such as Flight-Aware will be able to provide more exact historical flight paths. For users who do have in-flight Wi-Fi, services such as FlightAware will be able to provide almost real time location (note that many services have a 5 minute delay and are not really real-time), allowing future Wi-Fi connected zmanim apps to tap into this and provide accurate zmanim.
Is there a difference in time between the zmanim of chatzos hayom and chatzos halayla (astronomical midnight and astronomical high noon / midday) besides the obvious 12 hour difference?
I was recently asked by a developer why the KosherJava zmanim library does not have distinct calculations for chatzos halayla. The answer is that the zmanim API does indeed have the getSolarMidnight() calculation, but for the most part there is no real need for it. The time of chatzos halayla / midnight or chatzos hayom (solar transit / solar noon or midday) stays pretty constant from day to day. In the worst case scenario (on around December 22nd), the length of the solar day would increase by about 30.16 seconds from one day to the next. This does not change by location, but is the same anywhere in the world. This would mean that chatzos halayla could be a maximum of 15.08 seconds different than just using midday + 12 hours. This is something that should not really impact people. In addition, the developer in question does not even show seconds, making this a moot point. In short, chatzos on any given day should be considered accurate enough for both chatzos hayom and chatzos halayla of that day. It should be noted that the Mishnah Berurah quoting a number of achronim and the Shulchan Aruch Harav are of the are of the opinion that chatzos halayla is exactly 12 hours after chatzos hayom. The Mishnah Berurah states in הלכות הנהגת אדם בבקר א׳ ט׳
וזמן חצות הוא תמיד באמצעות הלילה ממש בכל מקום ואפילו בלילות הארוכות או הקצרות והיא י״ב שעות אחר חצי היום …
and the Shulchan Aruch Harav in הלכות השכמת הבוקר א׳ ח׳ states that
וזמן חצות לילה הוא שוה בקיץ ובחורף לעולם י״ב שעות אחר חצי היום שהוא אמצע הלילה ממש …
Chatzos Halayla on the Seder Night
The time of year that the zman of chatzos has the greatest impact is during the Pesach seder when people want to finish the afikoman before chatzos. During this time of the year the solar days are shrinking slightly from day to day, resulting in chatzos halayla being slightly earlier than chatzos hayom + 12 hours. The difference in the length of the solar day from solar noon on erev Pesach to solar noon on the first day of Pesach ranges from 11 to 18 seconds depending on the year. On the very late erev Pesach on April 24 that last occurred in 1929 and 1967 and will next occur in 2043 and 2062 there is an 11 second difference. On the extremely early erev Pesach of March 25 that occurred in 1899 and 2013 and will occur next in 2089 (see Rabbi Dovid Heber’s Why is This Pesach the Earliest Since 1899?) there is an 18 second difference. This 5.5 to 9 second difference in the time of chatzos hayom VS chatzos halayla on erev Pesach is something that has almost no real world impact. It is interesting to note that based on the fact that the average Jewish year is slightly longer than the average solar year, the early March 25 erev Pesach will never happen again after 2089.
Equation of Time (EoT)
You may have expected that the longest day of the year – the summer solstice (June 20 or 21 depending on the year) would be the day with the earliest sunrise / netz and latest sunset / shkiah (and therefore the day with the latest start of Shabbos). However the earliest sunrise actually occurs on or about June 14 (at latitude 40° – it varies slightly based on latitude), a week before the longest day, and the latest sunset occurs on or about June 28, a week after the summer solstice. As mentioned above, the length of the day that we know to be exactly 24 hours on a clock is actually only an average over the year. The length of the day varies slightly from day to day. This length of day range is from a minimum of 23 hours, 59 minutes and 38.64 seconds around September 17 to a maximum of 24 hours and 30.16 seconds around December 22 vs the previous day. This accumulated length of the day difference is known as the equation of time. While the day starts shortening after the solstice, chatzos (and by extension the entire day) is moving slightly forward as the solar day (midday to midday) grows at this time of the year, resulting in the day ending later despite it being shorter.
The cause of the change is due to the following two main factors. The very minor impact of nutations (such as the Chandler wobble), axial precession and other factors are too small to make a practical difference in the EoT calculations.
The tilt of the Earth’s Rotational Axis
The tilt of the Earth’s rotational axis (also known as the axial tilt or the obliquity of the ecliptic) as compared to the plane of its orbit around the sun is one factor that impacts the length of the solar day. To understand this, note that the earth rotates on it’s axis in 23 hours 56 minutes and 4.1 seconds in relation to the stars. This is called a sidereal day. The remaining 3 minutes and 55.9 seconds or about 0.98° of rotation must be made up every earth day. Due to the 23.44° axial tilt, this 3 minutes and 55.9 seconds is only an average.During the equinoxes the earth’s 23.44° tilt results in the sun having to travel a drop farther (1.09° for every 1° of eastward travel) to cover a line of longitude, since its path is angled and traveling a drop northwards or southwards on its path west. This results in the day being slightly shorter, since the sun only travels about 0.9° along the equator as opposed to the average of 0.98° per day. In the winter and summer the sun’s path is parallel to the equator and has a direct east/west path. In addition, since the longitude lines are closer together at 23.44° degrees from the equator the sun travels further moving 1.09° parallel to the equator for every 1° of eastward travel. This results in a slightly longer day. A technical and detailed explanation can be found in Mike G’s explanation of the subject at the astronomy section of StackExchange (where the above Stellarium generated images are from) and in Art Carlson’s equation of time explanation.
The elliptical orbit of the earth
The elliptical orbit of the earth (or the eccentricity of the Earth’s orbit) is the second factor that impacts the length of the day. The earth’s orbit around the sun is an ellipse and not a perfect circle. Following Kepler’s second law, the earth moves slightly faster in orbit when it is closer to the sun, and slower when it is farther away. During the perihelion (it ranges between January 2 and 6 depending on the year) when the earth is closest to the sun at 91,402,500 mi / 147,098,070 km distance, it travels at 30.287 km/s, while at the aphelion (between July 3 and 7) when it is 94,509,100 mi / 152,097,700 km away, it travels at 29.291 km/s. In addition, the angular velocity of the sun is faster (in relation to the stars) when it is closer to earth. Despite it being somewhat counter-intuitive, the sun is closer to earth in middle of the northern hemisphere’s winter than during the summer. This non-uniform orbital speed impacts the length of the solar day.
The Accumulated Difference
This difference between our standard clock time and the time that would be based on the exact position of the sun in the sky accumulates and is referred to as the equation of time (EoT). Equation in this case refers to equality and not a mathematical equation (though the calculations certainly involve mathematical equations), and adding or subtracting this time allows us to sync solar time and clock time (mean solar time / universal time).
Please see the references section below for links that cover the topic in detail.
- Sundials on the Internet’s The Equation of Time article.
- The US Naval Observatory’s article Sunrise and Sunset Times Near the Solstices.
- The US Naval Observatory’s article The Equation of Time.
- Wikipedia’s equation of time (EoT) article.
- A video about the equation of time by ScienceOnline.
- Ask Ethan: When Is The Earliest Sunrise And Latest Sunset Of The Year?
- Forbes’ Today Is Not 24 Hours Long.
- In-the-Sky’s Equation of Time article.
I would like to thank my son Shai for the detailed work on the technical part of this article.
A primer on the Halachic Dateline
A primer for this halachic dateline post if you are not familiar with the subject, is the earlier Halachic Date Line Map post about the Jewish date-line. Based on the opinion of the Ba’al Hamaor, the Chazon Ish ruled that the dateline is 90° east of Yerushalayim, and it can’t split a landmass. The concept of graira is used to drag the land past the dateline to the water’s edge. This concept of graira is based on the Yesod Olam, a talmid/disciple of the Rosh. For this reason, according to the Chazon Ish, Korea and Australia follow the local date and not the previous date.
Islands Connected to Mainland by a Bridge
A question touched on in the previous article that was mostly theoretical, was about an island connected by a bridge to the mainland. Would the concept of graira apply to the island? The kollel members in Melbourne and others do not visit Phillip Island on Sundays for this reason, but Chabad chassidim who do not follow the Chazon Ish’s opinion, do visit Phillip Island on Sundays.
Islands in Bays
There are differing opinions whether an island in a bay would also be included in graira. Rabbi Yitzchok Meir Goldstein in his השבת בכל מושבותיכם (pages 85-88) brings the following opinions. Rabbi Shlomo Zalman Auerbach in הליכות שלמה (Moadim, vol. 2, page 70) is of the opinion that an island in a bay would be considered part of the land that partially surrounds it. In the same vein, (but not specifically in reference to a bay), Rabbi Moishe Sternbuch in מועדים וזמנים vol 7, ch. 236 mentions something similar (that the easternmost border of Australia would be a vertical line from north to south at the longitude of Brisbane, the eastern-most point of Australia). What is not clear is how large a bay can be. Rabbi Goldstein mentions that drawing a line from Siberia to Malaysia (thus creating a “bay”), would put Japan on the same side of the dateline as the Asian mainland. The Chazon Ish clearly stated that Japan was past the dateline. Presumably, Rabbi Shlomo Zalman Auerbach and Rabbi Moshe Sternbuch would agree that such a large area would not be included in graira. Given the lack of detail about the size of bays, it is possible that these poskim would only include very small bays (within the techum perhaps). It should be noted that Japan is only in the “bay” if you use a rhumb-line. Drawing a great circle line would result in Japan being out of the “bay”. Rabbi Dov Landau in the פשר חזון, and Rabbi Moshe Heinemann do not include bays as part of the graira zone. Rabbi Sternbuch was asked about bays by Rabbi Goldstein, and he agreed that according to the Chazon Ish, bays would not be included in graira, so Rabbi Sternbuch either reversed his earlier opinion, or he disagrees with the Chazon Ish’s opinion.
There are related opinions that bays themselves do not drag islands within them into graira unless land to their east is part of graira. See Rabbi Leib Blum’s קו התאריך בכדור הארץ for details. For example the Sea of Okhotsk is to the west of the Kamchatka Peninsula. This means that they are of the opinion that you can’t have land to the east that is part of graira such as the Kamchatka Peninsula, and have Sea of Okhotsk and Sakhalin Island to the west of it that is considered past the line, (and back again to Siberia that is part of graira). The same would be the case in the portion of the Yellow Sea to the west of the Korean Peninsula and east of the Chazon Ish line, as well as the above mentioned Phillip Island and French island that are in the Western Port Bay near Melbourne. Bays such as Moreton Bay that includes Bribie and other islands near Brisbane, as well as Ulleungdo Island in the Sea of Japan would not be included in graira, since there is no graira land to the east of it.
Incheon International Airport and the Halachic Dateline
In January 2019, the Star-K held a Kashrus training seminar in Shanghai for mashgichim who live or work in Asia. Among the sessions, was a shiur about the halachic dateline by Rabbi Dovid Heber who shared the URL to my halachic dateline map with the participants. One of the mashgichim, Rabbi Yosef Wexler, who travels from Eretz Yisrael to Asia regularly, noticed a potential issue related to the Incheon airport, the main airport in South Korea (near Seoul). The airport is located on Yeongjong Island, that is connected to mainland South Korea by two long bridges. The island is within a Bay (formerly Chemulpo Bay), that is itself within the Yellow Sea that is itself a vary large bay. If graira would not apply here (bridges and bays would not be considered a connection) and you followed the opinion of the Chazon Ish, the airport would observe Shabbos on local Sunday (the same issue faced in Japan). This impacts mashgichim who bypass Japan on Sundays, and regularly fly to Korea on flight KE958 on Motza’ei Shabbos from Israel on their way to China etc. The flight lands at about 3pm Sunday local time, when the airport may be observing Shabbos. It would also impact anyone else who plans on flying in or out of the airport between Motza’ei Shabbos and Sunday night.
Please consult a posek before relying on this for halacha lema’aseh. There are a number of opinions, and I will touch on a few of them.
As per Rabbi Heber, Rabbi Yonasan Weiner (a posek in Ohr Sameach) asked R’ Chaim Kanievsky about Phillip Island (that as mentioned above, has a bridge and is in a bay), and he said that it is ‘צריך עיון’. Based on this, Rabbi Moshe Heinemann ruled that if someone is in the Incheon airport from shkiah on Friday (local day) until it gets dark on Saturday, one should keep regular Shabbos. From when it gets dark on Saturday night until it gets dark on local Sunday deoraisas should be avoided, but derabanans are permissible. This would permit most activities. The following quote in Rabbi Yitzchok Meir Goldstein’s השבת בכל מושבותיכם should be noted:
שמעתי מדודי הגאון רבי משה היינעמאנן שליט״א שאולי גבול היבשה הוא כשיעור תחום שבת מסוף היבשה
Yeongjong Island is at its closest 1,950 meters from mainland South Korea (from the eastern tip of the island to Wolmido, a former island that is now connected to land), and thus beyond tchum Shabbos. It is therefore not within the extended maritime graira zone. This applies to Incheon, but not the Yellow Sea. Rabbi Heber in his note to the Star-K mashgichim stated that melachos deoraisa should not be done within 35 minutes of landing since that is the earliest time the KAL958 flight passes the Chazon Ish line over the Yellow Sea. At this point according to the Chazon Ish it would be Shabbos. This was also mentioned by Rabbi Goldstein as a possible deoraisa. See below for more details.
Permissible Activities on Incheon Island on Sundays
There are many variables and variations in various melachos, so please consult a posek before relying on this for halacha lema’aseh.
Note: This list is only meant for Incheon airport on Sundays (from Motza’ei Shabbos until it turns dark on Sunday night) and other areas where a majority of opinions hold it is a weekday, but an accepted minority hold it is Shabbos. This list should not be used in any other locations or on a day that is accepted as Shabbos.
- Traveling as a passenger to and from Incheon airport by plane or car. You do not have to worry about the 12 mil tchum Shabbos.
- Carrying your belongings more than 4 amos outside the airport, or carrying them into the airport – there is no reshus harabim deoraisa on the island
- Deplaning with your muktzeh luggage.
- Walking in the airport including the use of escalators and moving sidewalks.
- Triggering automatic sensor doors, sensors in bathrooms etc. (there no need to wait for someone else to activate it).
- Scanning boarding or other passes (including to open electronic gates).
- Going through security, taking muktzeh out of pockets, and passing through metal detectors.
- Electronically signing into a lounge.
- If a paper signature or writing is required, try to avoid it. If there is no other option, use your alternate hand (left for a righty, right for a lefty). An ambidextrous person can’t do shinuy by changing hands, and can’t sign or write.
- Typing on a computer and typing or calling with cellphones is permissible, but the screen saver or the automated powering down of the monitor has to activate by itself to “erase” your writing. For power saving and security reasons, almost all computers will end up having a screensaver or a monitor power down and clear the screen. If this is not in place, and your “writing” will remain on the screen, it is more of a maaseh ksiva. Saving the document to your hard drive is permissible.
Problematic Activities During This Time
- Opening a taxi door that causes the dome light to turn on (ask the driver to open your door, or have him open his door first, thus turning on the dome light)
- Writing (with paper and pen).
- Showers in the lounge should be avoided since there can be deoriasas involved.
- Making coffee should be done the same way you would do it on Shabbos. Instant is fine, brewing fresh in a machine should not be done.
Rabbi Shlomo Miller in his approbation to the above mentioned Hashabbos Bechol Moshvosaichem, mentions that:
… והביא שטה אחת דכדי שיראה הוי בכלל אסטרליא וכן הי׳ דעתי נוטה [כמובן א״א להביא ראיות ברורות בזה] אולם יש להוסיף דלפי הגמ׳ בכורות נ״ד: עד ט״ז מיל הוי שעור כדי שיראה ויש אחרונים שהביאו מזה לגבי היקף מחיצות בשבת במחיצות הנעשות מאליהן דצריך שיהא העומד בתוכו רואה את המחיצות ע״כ עד ט״ז מיל יש מקום להסתפק אפשר שנגרר אחר אסטרליא.
This intuition (that he is unsure of) would potentially remove the questionable status of Incheon airport.
Rabbi Shmuel Meir Katz, a posek in Lakewood, discussed the Incheon airport question (focused on the fact that it is on a a man-made portion of the island) in his Time Zone Shailos speech at the The Association of Kashrus Organizations’s 2018 Vaadim conference (24:50 into the recording). He said that a chaburah in Lakewood, NJ brought down a תוספתא נגעים פ״ו ה״ג that ״בית שבים אין מטמאין בנגעים״. The גר״א has a girsa ״בית שבים מטמאין בנגעים״. The ר״ש in נגעים פ׳ י״ב מ״א explains that
בית שבים: מדקתני בית שבים ובית שבספינה משמע דתרי מילי נינהו דשבים אפילו בנוי על גבי קרקע הים שהביאו אבנים וטיט ושפכו בים עד שנעשה כמין תל ובנו עליו בית אין מטמא בנגעים משום דכתיב ״ארץ״ ולא ים
This implies that the only questionable status is for נגעים, but otherwise, man-made land would have the status of natural land. Rabbi Katz holds that the bridge itself would connect the island and give it the same halacha as the mainland. It should be noted that Rabbi Katz also discussed the issue of The Sea of Okhotsk. His opinion is that the line follows the contour of the land, and the Sea of Okhotsk and Sakhalin Island would not be included in graira, but mentioned that Rabbi Leib Blum felt that it should be included due to it being to the west of land that has graira.
Rabbi Mordechai Kuber in his upcoming book, Crossing the Dateline (expected to be published later this year) strongly feels that there is no problem in Incheon airport on Sundays due to it being in a bay (that is in itself a safek). The question of the bridges, its proximity to land, and the many sandbars between it and the land make it at most a sfaik sfaika, which most poskim should agree is not an issue even according to the Chazon Ish. This sfaik sfeka is in addition to the other opinions who do not agree with the Chazon Ish, and are of the opinion that Incheon is not east of the halachic dateline, and therefore Saturday is Shabbos in Incheon, and not Sunday.
Rabbi Yitzchok Meir Goldstein in a letter to me mentioned that there is a possibility of a deoraisa in flying on a flight that is completely or partially on Shabbos
… this is comparable to one who boards a plane which takes off before Shabbos and lands after Shabbos, which, as the Shailos U’Teshuvos Minchas Yitzchok 2:106, the Shailos U’Teshuvos Tzitz Eliezer 1:21 and the Shailos U’Teshuvos Shraga HaMeir 7:27 write, involves an issur d’oraysa transgressing the chiyuv
of “shabosson” which is not fulfilled while on an airplane ride. (However, it could be that there is a sevara to say that there is a difference in the d’oraysa of “shabosson” between flying on an airplane for the whole Shabbos and flying over the Yellow Sea for a short time …). If, indeed, this involves an issur d’oraysa, this creates a problem not only for people who follow the opinion of the Chazon Ish with regard to the dateline, but even for people who refrain from issurim d’oraysa on the Shabbos of the Chazon Ish. If so, regardless of whether or not the sevara of graira applies to Incheon Airport, I would think that people should still not be flying to that airport on Sunday. Second of all, even if I am mistaken in the above comparison and there is no issur d’oraysa to fly over the Yellow Sea while it is Shabbos in the Yellow Sea, it would be worthwhile for you to mention in your article that at least while the airplane is flying over the Yellow Sea one should certainly be careful not to perform any melacha d’oraysa such as writing. I am not trying to offer a psak about these points, but I think there is reason to consult with a poseik whether these issues need to be mentioned in your article.
It should also be noted that on page 83 of השבת בכל מושבותיכם, Rabbi Chaim Kanievsky is quoted with a different psak than the one quoted above by Rabbi Yonasan Weiner. Rabbi Goldstein sent the following question to Rabbi Chaim Kanievsky
שמעתי שבחוף הים של אוסטרליה יש גשרים ובנינים שנבנו בידי אדם שיוצאים מן היבשה לתוך קצה הים, האם גם בנינים אלו וגשרים אלו המחוברים ליבשה נגררים אחר שאר ארץ אוסטרליה או רק הארץ שנעשה שם בידי שמים ולא מה שניתוסף בידי אדם בתוך הים?
Rabbi Kanievsky replied with his typical brevity
I would like to thank Rabbi Dovid Heber, Rabbi Shmuel Meir Katz, Rabbi Yitzchok Meir Goldstein, Rabbi Mordechai Kuber, My father-in-law R’ Feivel Muller and my wife for reviewing this article.
This article is published in memory of my mother-in-law Mrs. Helen Muller חיה בת ר׳ יצחק הכהן ע״ה.