Panic. Best is breathing exercise. This is done thru closing your eyes & breathing slowly while counting numbers. I can give you details of how to do those exercises if you want to e-mail me request, due to limited space here to write down. These exercises can abolish panic attacks in 5 mins. & can be done anywhere.
Therapy. Unfortunately, most people wait until the week before flying to ask that question. Therapy takes some time, but is very effective. If no time, meds can be effective in the short run.
Start days ahead. We've had great success treating this. I've found that the fear builds relentlessly as the travel date approaches so the key is to prevent the buildup of anxiety by treating with anti-anxiety meds (clonazepam) for as much as a week prior to flying. The dose changes/increases; we give a precise schedule of dosing, esp on the day of travel. Fly w/ a calm person;begin w/ short flights; get roomy seat.