Latest update: April 26th, 2013
The Talmud comments that if indeed the reshut harabim extends beyond the height of ten tefachim for the purpose of techum Shabbat, then Eliyahu the prophet (who according to tradition will announce the arrival of the Messiah) and the Messiah himself will not be able to arrive on Shabbat, because their descent would violate the “beyond the techum” prohibition.
Some rishonim suggest that this passage in the Talmud is the reason why we welcome Eliyahu Hanavi after Havdalah – because only then will he be able to arrive without violating the “beyond the techum” prohibition. Based on the majority opinion – that the “beyond the techum” prohibition is of rabbinical origin and therefore there is more room for leniency – the Rama concludes that sailing beyond the techum Shabbat is permitted even when in doubt as to whether the hull is ten tefachim above the bed of the sea. For the same reason, Rabbi Blau, in his treatise on Eruvin, suggests that under certain circumstances one may disembark from a plane that arrived after the onset of Shabbat because the distance of the techum Shabbat would be measured from the point of landing.Raphael Grunfeld
About the Author: Raphael Grunfeld’s book, “Ner Eyal on Seder Moed” (distributed by Mesorah) is available at OU.org and your local Jewish bookstore. His new book, “Ner Eyal on Seder Nashim & Nezikin,” will be available shortly.
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