This is not the first time that El Al is faced with problems with ultra-Orthodox people on board flights to religious sites. In 2002, a flight crew had to prevent an ultra-Orthodox passenger, flying from Israel to Britain, from wrapping himself in plastic bags. The pilot was forced to return to Ben Gurion International airport in order to remove the passenger from the plane. The passenger, a Cohen, wrapped himself in plastic bags for fear that the plane's route would pass through the air above the Holon cemetery and he would consequently become impure.
Rabbi Yosef Shalom Eliashiv, the leader of the Lithuanian Haredi community in Israel, published a halakhic ruling in the past stipulating that Cohens mustn't fly in this plane because they are prohibited from flying over a cemetery. Later, Rabbi Eliashiv found a solution to this issue, ruling that wrapping oneself in thick plastic bags while the plane crossed over the cemetery is permissible.
http://www.haaretz.com/news/ultra-orthodox-passengers-riot-aboard-el-al-plane-over-screening-of-film-1.243447
First, an introduction. Some members of the Jewish Faith can trace their ancestral roots back to Ahron, brother of Moses, the first Kohen (as in Cohen) or Biblical Priest.
As the Torah-Bible clearly states in Leviticus Chapter 21, a Kohen can not come into contact with a dead person except for an immediate relative.
In any case...................It seems that flights leaving Tel Aviv, fly over a cemetery in Holon, creating a problem for any Kohen in flight.
http://www.flyertalk.com/forum/other-middle-east-africa-frequent-flyer-programs/61923-flying-over-holon-cemetery.html
Place is huge

I have to wonder if Rabbi Yosef Shalom Eliashiv does not realize the plane itself is sealed.