I feel like you are implying conspiracy-like behavior, instead of recognizing the absurd rarity of the event:

> "Over a two-year period, nearly 400 pilots, flight attendants and passengers reported receiving medical attention after these “fume events,” and four dozen pilots were described as impaired to the point of being unable to perform their duties, The Times found."

This same two year period flew about 280 million "passengers", obviously not unique, but 400 / 280 000 000 ~= 1 in 15000

I don't think that this is about being covered up so much as obfuscated. That's a low-frequency event.