Halakhah zu Wajikra 21:1

Said R. Levi: Because of Aaron's awe of the Holy One, blessed be He, he was privileged to be given this section which does not depart from him, his sons or his grandsons, until the end of all generations. Which [section] is it? It is the section of [defilement of] the dead, as it is said, "And God said to Moses: Speak unto the priests, the sons of Aaron…" (Leviticus 21:1).

A few points need to be clarified before we begin our discussion. The Torah (Vayikra 21:1) forbids kohanim to come in contact with the dead. This restriction, however, applies only to male kohanim (Sotah 23b, cited by Rashi to Vayikra 21:1). Contact with the dead includes being in the same building as a dead body (Bemidbar 19:14). ²For a summary of whether this rule prohibits kohanim from entering hospitals, see Nishmat Avraham (2:209-210). For further discussion of this issue, see Techumin (19:323-334). Although children are not personally obligated to observe this restriction, adults cannot deliberately cause even the youngest of kohanim (even an infant) to come in contact with a dead body (Mishnah Berurah 343:3 and Aruch Hashulchan Y.D. 373:1).

As recorded in Leviticus 21:1-4, other than in conjunction with the burial of a close relative, kohanim, the descendants of Aaron, are forbidden to defile themselves through contact with a corpse. Late in the summer of 2001 Rabbi David Morgenstern of Jerusalem was approached by a newly-observant Israeli pilot who relayed a question raised by a colleague: How is it that kohanim are permitted to embark on flights leaving Lod that pass over a cemetery in Holon? Upon investigation it was discovered that the situation has been in existence since some time in 1984 when flight patterns were altered to minimize flights over densely populated areas north of Ben Gurion airport and to avoid overflying a military area south of the airport. Although the details are not clear, it seems that some night flights departing to the United States use an alternate route but that all flights to European cities fly over Holon. It is reported that government officials have given assurance that flight plans would be altered in order to obviate the problem but that, in actuality, such changes have not been implemented.