Daniela: Eh, I don’t eat macrobiotic, but nice attempt at a personal attack. If you read what I wrote carefully, you’ll see that I didn’t say that bitul applies to tumah.
I just meant to observe that there are ways to be lenient in various areas of halacha — and I’d be very surprised if most poskim side with the notion that accidentally being for a split second thousands of feet above a cemetery is absolutely forbidden for kohanim.
In fact, if this were really an accepted ruling, we’d see kohanim in plastic bags (or refusing to fly at all) all the time! Yet there are only a handful of kohanim who have ever done this.