Think that's a peristaltic chain reaction - one person voms and the sight, sound, smell or combo of all three, set off those nearby. I once witnessed the phenomenon on a rather bumpy approach to Las Vegas.
Good way to combat that syndrome is to carry a small bottle of Olbas Oil (tiny tiny - much less than 100ml!). Quick dab of that on a paper hankie and hold it under your nose - all you'll smell is clean menthol/eucalyptus. Turn up the headphones if you have anything to drown out the sound and find something interesting to read in the in-flight magazine (the fact that you'll have to really search hard for something interesting to read, is a useful distraction technique).
I hurl if I look at a glass of water too long but fingers crossed have been OK with airline flying so far. My magic preventative is Stugeron. I've only chucked n a plane once and that was due to an unmedicated migraine.