As you will see in the recent "Another New Member" Discussion Forum, and also in the latest question asked in the Community Expert section, there are reports (even by some of our members) that air travel can trigger an episode of SCLS.
As I have explained in the latter, episodes of SCLS are triggered by stress and airborne illnesses like colds and stomach viruses in individuals that may have lost a crucial component of their immunity. Therefore, it may not be the air travel itself, but what is in the recirculated air of an aircraft, that may lead to an episode.