Eruvin 41 and 43 Landing on shabbos, Flying Elijah, and תחומין למעלה מעשר

One of the nightmares faced by the Torah observant traveler is the possibility of a flight being delayed and arriving at the destination airport on Shabbos.

While whether being on a plane per say on shabbos poises any halachik problems is a subject deserving its own discussion, once a person is already in the air, this is no longer within his control.

However, on landing, one is phased with various issues.

Some of them could be faced at the airport itself, if the entire airport is not one large private domain, or if entry forms needs to be filled in on arrival, not to mention luggage handling.

However, one of the most challenging issues is if and how one may get home or to the nearest Jewish community  from the airport.

Even if one is able to leave one’s luggage at the airport and walk, one must deal with the issue of תחומין, the main topic of our perek.

The opening Mishna of the perek taught us that if  a person left his techum (shabbos domain) on shabbos, even by force, he is not permitted to return on shabbos and is confined to the 4 amos radius he currently finds himself in, a seemingly very harsh ruling for a rabbinical prohibition.

This applies even if he is inside the techum of a house or city.

It follows that if a person left the techum that he found himself in during twilight on erev shabbos, whether the departure city or wherever he was in the air at the time, something that doesn’t take very long on  a plane, he might be required to stay within 4 amos of wherever he lands up on shabbos, and not even be able to walk within the techum he has landed in.

The rule that an enclosed area is considered like 4 amos (also discussed in our current dapim)  might allow him to walk within in the airport itself, depending on how that sugya is interpreted and concluded, but leaving the airport would be forbidden.

In truth, this is not a totally new question from the age of aviation but is tied to an old question regarding people who disembark from a ship on shabbos.

In our Gemara, Rav Chananya asks whether the laws of techumim apply more than 10 tefachim above the ground or not.

At first glance, it seems that this must have something to do with the fact that  an area more than 10 tefachim above the public domain is either a private domain (if it has the minimum width) or a מקום פטור , and walking on it is thus considered insignificant when it comes to techumim.

The Gemara immediately clarifies that a pillar that is more than 10 tefachim high and 4 tefachim wide, part of it within one’s techum and part of it outside the techum, may certainly not be used as a legal way of leaving the techum. This is because it is considered ארעא סמיכתא (solid or supporting ground,) a phrase we have seen before regarding land that slopes at a comfortable gradient for walking up  as well as the area below 3 tefachim in a public domain.

In this context, Rashi explains that because it is fit for walking on (presumably due to its flat and wide nature), walking on it is considered הלוך מעליא  (proper walking) and the laws of techumim certainly apply.

It therefore limits the question to a pillar or raised area that is less than 4 tefachim wide, which is harder to walk on , to someone jumping from inside his techum to outside it, or according to a different version,  to a boat in water more than 10 tefachim deep, which is also considered to be 10 tefachim above the ground.

It seems from this that the question about whether the laws of techumim apply above 10 tefachim or not has nothing to do with it being a private or exempt domain as opposed to a public domain or Karmelit, but rather to do with the fact that it is not an area fit for normal walking.

This requires further analysis, but moving on through the sugya, the Gemara suggests various proofs that the laws of techumim do not apply above 10 tefachim.

The first proof is from a case in our Mishna, involving a boat at sea, which the Gemara now seems to take for granted is considered to be above 10 tefachim from the ground .

The Mishna brought the case of various Tannaim who were on a boat on shabbos. Once they had left the techum, they were technically not allowed to move outside the 4-amah radius they were sitting in at the time shabbos started.

Yet Rabban Gamliel and Rabbi Elazer ben Azaria walked anywhere on the boat, in keeping with their rule that an enclosed area is treated like 4 amos.

Rabbi Akiva and Rabbi Yehoshua, who did not accept this leniency when it came to someone who left his techum on shabbos, predictably stayed within their 4 amos.

If the laws of techumim do not apply above 10 tefachim (like in a boat at sea,) their stringent action makes no sense.

As such, the Gemara wishes to conclude that the laws of techumim  do indeed apply above 10 tefachim.

This proof is rejected given the possibility that laws of techumim do not apply above 10 tefachim but they still wanted to be strict on themselves, in case they passed through shallow water which put them within 10 tefachim of the seabed.

The Gemara brings another two proofs which are both rejected, but now that we have seen that the Gemara takes the view that a boat is to be treated as being higher than 10 tefachim so long as the water it is sailing in is more than ten tefachim deep, I will proceed for now to the final attempted proof.

The Gemara brings a case where someone made an oath that he will be a nazir on the day that the son of David (Mashiach) comes.

Such a person must act like a nazir during all weekdays going forward, seeing as mashiach might have come that day  already and he is simply not yet aware of it.

However,  on shabbos or Yom Tov, he does not have to act like a Nazir.

The Gemara assumes at first that this is because Eliyahu haNavi needs to accompany him and is not permitted to travel so far out of his shabbos domain to do so- apparently even though he is able to fly (an assumption whose halachik significance needs its own discussion of course.)

It thus wishes to conclude from this that the laws of techumim indeed apply above 10 tefachim, otherwise flying such a distance would not represent a problem for him.

The Gemara refutes this proof, given that the passuk in fact tells us that Hashem will send Eliyahu “לפני בא יום ה” – BEFORE the day of Hashem comes, namely the day before.

As we were promised that Eliyahu would not come on a Friday, to avoid disturbing our busy shabbos preparations (itself quite an astonishing statement about the importance of shabbos preparations,) it follows that Mashiach will not come on a Shabbos, and he does not have to act as a nazir.

The Gemara then asks why he is not also exempt from  his vow on a Sunday- after all, seeing as Eliyahu cannot come on Shabbos because of techum issues, Mashiach cannot come on a Sunday- it wants to prove from the fact that he is not exempt on Sunday that Eliyahu could indeed come on shabbos, because there is no prohibition of techumim above 10 tefachim from the ground!

The Gemara answers that it unable to derive from this that there is definitely no issue of techumim on shabbos because it is possible that this was unsure whether techumim apply above ten tefachim or not.

Due to this uncertainty, the vower must take into the account that Eliyahu (who knows the halacha even if we don’t)  might have come on Shabbos, and thus must act as a Nazir on Sunday out of doubt.

However, that does not mean that we can prove from here that there is certainly an issue of techumim above 10 tefachim.

As such, the core question regarding whether the laws of techumim apply above 10 tefachim remains unresolved in the Gemara.

Although we are strict regarding his vow, keeping with the rule of ספק דאורייתא לחומרא , as far as the rules of eruvin themselves are concerned, it follows that we might apply the general rule that in matters of doubt ספר עירוב לקולא .

Assuming that this rule in turn is a derivation of the general rule of ספק דאורייתא לחומרא (something we touched on briefly in an earlier post but that requires further analysis,) it would then follow according to the opinions that תחומין   are biblical after 4 parsa (about 16 km) ,  this leniency might not apply if he has travelled more than that amount since twilight on erev shabbos, an almost certainty with air travel. (see however Ramban, who raised and rejects this distinction.)

Putting the above concern aside, it follows that where prohibitions of techumim are involved, we might be lenient and someone who has travelled through the air, like one who has travelled through the sea, has not transgressed any techum related prohibitions and is thus not subject to the 4 amos restriction.

However, it is still not so simple.

Besides for the question of the larger biblical techum, there is also the question of when and where his shabbos base is determined to be.

After all, if there are no techumim above 10 tefachim, and he was at sea or in the air during the critical twilight period of erev shabbos, he had no techum to become his shabbos base at that time, and it could be argued that he thus has NO shabbos base other than his own 4 amos.

If this were true, then even if disembarking were permitted, and even if he were to be allowed to enter the terminal building,  he would not be allowed to leave the port or the airport on shabbos!

The Ramban notes that he has seen many who have the custom to indeed stay in port under such circumstances.

He suggests that this might be based on the Raavad who understands the Gemara as concluding that we are strict out of doubt regarding techumim above 10 tefachim, not only regarding the vow, but also regarding the laws of Eruvin, an exception to the general rule of ספק עירוב לקולא.

He rejects this view out of hand, and then suggests that it might be due to the above concern regarding him not having any shabbos base at all.

Bringing various sugyos and Rishonim as support, he concludes that this is not a concern, and that in the  absence of a person’s shabbos base being defined during twilight, it is defined as the first valid techum he enters on shabbos itself, in this case the port or city he has arrived in .

Given that, he could technically walk as far as anywhere within the city and within a 2000 amah radius of it.

This would obviously only apply if the port, the parts of the city he walks through, and his home  are halachically considered within the same city (with gaps of less than about 140 amos between the houses or enclosed property’s walls,) something that might apply in city airports but not in many international airports that serve large cities but are situated outside the halachik city  boundaries itself.

Furthermore, unlike a boat which sails in the water till the moment it reaches port, a plane reaches 10 tefachim of the ground just before landing, far away from the airport terminal on a long runway ( a point I saw was raised by Rabbi Daniel Dombroff of New Jersey in a brief online post on the subject.)

Even with the Ramban’s reasoning,  his first valid shabbos base would then be by the landing site, which is unlikely to be in an area that is מוקף לדירה  (surrounded for purposes of dwelling) and is almost certainly in an area larger than a בית סאתיים  (5000 squares amos or about 500 square metres,) and unlikely to be within the techum of the city (though once we square the city and its 2000 amos to define its effective techum, the later is certainly still possible.)

As such, he would only have 2000 amos from that point, and it is likely that by the time he gets to the terminal building, he will have already left his techum and thus at best, be confined to the terminal, and at worst be confined to the 4 amos he is dropped off in.

This seems to be the  basis of common practise to avoid leaving the terminal building, even if the terminal is within the techum of his city.

However, I see some theoretical reasoning for being lenient regarding walking from an airport too, when the terminal is within the city’s techum, in a similar way that the Ramban was lenient in allowing one to walk home from the seaport so long as the port is within the techum of the city.

This is because the plane itself is more than 10 tefachim above the ground, even once it has landed.

Even though some opinions are stringent with a wagon, considering it to be ארעא סמיכתא , a plane while taxiing is very different to a wagon for various reasons, among them:

i.                     It is in a state of continuous and forced motion and cannot simply stop when it wants.

ii.                   It is not only difficult, but both dangerous and forbidden to walk around on it during the taxi stage. (I was interested to see that in a different context, for this and other reasons, מראה הבזק חלק ה brings reasons for leniency even in a wagon or high motorcar)

As such, there is a strong case that his first viable shabbos base to be encountered is not the point at which the plane lands, but at the point where the plane stops, which is far more likely to be within 2000 amos of the terminal or even within the techum of the city.

This is obviously far simpler when an airbridge is used, rather than a bus system, given that there are bona fide partitions around the whole area he will be walking through.

In practise, due to the extreme complexity of this question and the many variables which can change the halacha, it indeed seems hard to be lenient and allow one to leave the terminal building.

It goes without saying that one should do one’s absolute best to ensure a good safety net of time between anticipated landing and shabbos to allow not only for usual arrival procedures and travelling home, but for a reasonably normal delay, and if it is clear that one will land after shabbos once on the plane, to request permission to disembark before take-off.

However given that this is a common issue, perhaps Jewish communities could be encouraged to  get an eruv expert to map the techum of their city and establish whether their airport is indeed within its techum, in which case local halachik authorities  could rule that  in cases where staying at the airport over shabbos is an extreme destruction of one’s Oneg shabbos and/or involves serious discomfort, walking home or to a community center or member’s home might be a valid option.

Though I have not researched the geography of Moscow, it could be that based on the below link,this is precisely what Russia’s Chief Rabbi once did!

These posts are intended to raise issues and stimulate further research and discussion on contemporary topics related to the daf. They are not intended as psak halacha.

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