Question: Is one permitted to begin a journey before Shabbat when one knows that he will be forced to desecrate Shabbat due to a life-threatening circumstance?
Answer: In the previous Halacha, we have discussed the prohibition of setting sail on a ship (for a non-Mitzvah purpose) within three days of Shabbat. Our Sages forbade doing so because this will cause a lack of enjoyment of Shabbat, for it is well-known that during the first three days of a sea voyage, passengers usually feel nauseous and dizzy as a result of the salty water and movement of the ship which will thus impair their ability to adequately fulfill the Mitzvah of enjoying Shabbat. Our Sages therefore decreed that one may only set sail on a ship on the days not immediately preceding Shabbat.
Until now, we have explained the law when no Shabbat desecration is involved in setting sail and the only concern is a lack of enjoyment of Shabbat.
Maran Ha’Shulchan Aruch (Chapter 248, Section 4) writes as follows: “Those who travel as part of a caravan into the desert and it is certain that they will be forced to desecrate Shabbat, for they cannot halt their journey and stay in the desert alone since this is quite dangerous, they may not begin their journey beginning from three days before Shabbat. However, they may begin their journey on Sunday, Monday, or Tuesday. If one is moving to Eretz Yisrael, however, even if one happens upon a caravan beginning their journey on Erev Shabbat, one may join them since this is for the purpose of a Mitzvah.”
This means that one may not place himself in a situation where one will be forced to desecrate Shabbat as a result of beginning one’s journey. For this reason, it is forbidden to begin one’s journey into a desert on the days preceding Shabbat. However, if one begins one’s journey in the beginning of the week, namely Sunday, Monday, and Tuesday, this is permissible. Even if one is will be forced to later desecrate the Shabbat, one may do so and this does not constitute Shabbat desecration. One should preferably try and stipulate with the members of the caravan that they not desecrate Shabbat. If they do not uphold their commitment and later desecrate the Shabbat, one may continue along with them because of the danger involved (see Chazon Ovadia-Shabbat, Part 1, page 122).
In the following Halacha we shall discuss whether or not one may schedule a medical procedure or operation on the days preceding Shabbat.