Secondhand smoke also upsets my stomach, so I'd agree this could be a major factor. It's amazing to think smoking used to be so common in the confined plane cab

Secondhand smoke also upsets my stomach, so I'd agree this could be a major factor. It's amazing to think smoking used to be so common in the confined plane cabin: every plane like those glass-encased "smoking areas" remaining in many airports! Moderated drinking habits probably also play a role: when flying was rarer, and a rougher ride, throwing back excessive drinks before/during/between flights may have been a bigger part of the adventure – then also boosting airsickness rates.