My personal opinion as someone who spent almost 4 years flying the 777 until recently is that the cabin air thing may not be the whole story. Now, since this is now an emerging major public issue, it would be nice to know if Boeing had had a problem like this in mind when they fitted the ionisers in the air system. I'll leave that there....
My feeling is that the main problem is in the actual logic that controls the fly-by-wire system. It is designed as part of its role to constantly make small corrections to the flying surfaces to maintain the most efficient angle of attack for the current aircraft configuration and ambient conditions. This seems to translate, in the cruise, to an almost (or actually) subliminal oscillation of the tail in an oval, or figure of 8 manner. In some people my feeling is this may be what induces motion sickness. I do feel the cabin-air recirculation is a Red Herring on this one.
Either way, it should not be swept under the carpet, but I would err on the side of control system programming logic first, before any other cause. Costs a lot of money to rewrite millions of lines of code, and then, as that code is central to the operation of the aircraft, it would then have to be re-certified, I think. Not the cheapest option, that one.
Personal opinion, based on experience as a line pilot, nothing more. Pinch your salt accordingly.
£6
[This message has been edited by Sick Squid (edited 06 May 2001).]