Question:May an American visiting Israel who keeps one day of Yom Tov fly on the day after Pesach in Israel (Yom Tov Sheini abroad) if he will land at his destination after Yom Tov there?

Answer:We will only touch on the question of a ben chutz la’aretz (a Jew who lives in the Diaspora) keeping one or two days of Yom Tov in Israel. We believe that both opinions are defendable and legitimate and are glad that the machloket has not become a divisive one. A basic understanding, though, is critical to deal with this case.
Bnei chutz la’artez keep two days abroad because of the binding minhag to treat the second day as if it might be the first even after the calendar was set (Beitza 4b). Those who keep two days reason that this applies even in Israel since a community’s minhagim and accepted stringencies are binding upon them even while visiting elsewhere (see Pesachim 50a). The Chacham Tzvi (166) argues that the rule of keeping one’s community’s practices does not apply to matters that are dependent on the place. Since if the whole Diaspora community would come to Israel, they would not need and would not be allowed to keep an extra day of Yom Tov, the individual in that situation should also not keep a second day in Israel.
Let us analyze the unique situation on this plane. Israeli travellers do not have a problem because they are not obligated in a second day of Yom Tov unless they move permanently to the Diaspora or need to refrain from work on Yom Tov within a Diaspora Jewish community (the plane does not qualify). In contrast, the American traveler is a ben chutz la’aretz, who is fundamentally obligated in a second day. The Chacham Tzvi’s logic no longer applies, as a plane over chutz la’aretz is not in Israel even if it took off from there. Therefore, the visitor would enter his natural obligation of Yom Tov Sheini on the plane.
One might claim that Yom Tov status cannot change in the middle of the day. However, the accepted opinion is that one who makes aliya (e.g., by boat) or makes the decision to remain permanently in Israel on Yom Tov Sheini changes his status in the middle of the day (Yom Tov Sheni K’hilchato 4:6). (The logic of the minority who disagree seems to apply only to ridding oneself of the kedusha that was accepted, not to preventing it from starting in the middle of the day- see B’tzel Hachochma I:53). We find the idea of entering into days in the middle regarding sefirat ha’omer and other halachot for those who pass the International Date Line (see our teshuva in the Hebrew version of Hemdat Yamim, Vayeitzei 5773; article by Rav Z. Ryzman, Techumin XXXII, p. 30).
Is it permitted to put oneself in a situation that he will experience Yom Tov on a plane for several hours? Under certain circumstances, it is permitted to enter a ship even though he will be on it on Shabbat (see Shulchan Aruch, Orach Chayim 248:1), and we could not make a blanket ruling regarding those who feel they have to leave Israel right after Yom Tov. In some ways, a plane is better than a ship and in some ways worse (see referenced articles in depth). However, there are so many difficulties with this arrangement (purely halachic and technical created by the halacha) that we strongly discourage taking such a flight except under extreme conditions. A few examples of difficulties follow. One would not be allowed to lock the door to the bathroom because lights go on. He could not look at the television screen. Muktzeh applies to such things as passport, boarding pass, and customs declaration. It is likely that he would even be obligated in Yom Tov davening, full Kiddush, and lechem mishneh. He cannot eat chametz.
In summation, even those bnei chutz la’aretz who keep only one day of Yom Tov in Israel should not take off from Israel while it is still Yom Tov Sheini. If they do they should treat that time on the plane as Yom Tov. We are willing to give advice to one who finds himself in a situation that he has little choice but to fly then.