My recent study shows:
Meisim FROM USA:
ElAl from Newark doesnt take meisim because theres no scanner big enough for coffins.
United from Newark takes meisim on all flight, and all meisim from the USA are routed through there.
ELAL JFK: Takes meisim, However they will tell you if they expect a meis and will alow you to go onto the next flight for free.
M"ikkur Hadin, ELAL places a tefach between the meis and aron, this stops the Tumas Ohel, so you would be able to fly any ELAL flight to Israel.
FROM ISRAEL:
Flights leaving from shortly after sunset until 12AM go over Cemetery, this ends at 12AM because of noise over populated areas.
Facts may change, and my review may contain some errors,
as always contact your LOR.
Reb Nissin Kaplan has told me that he goes into a body bag for a certain amount of time about 2 minutes into flight, and that as well breaks the tumma.