I am very glad to have come across this thread as I have been battling claustrophobia for years. While my main triggers are elevators, I experience a great level of anxiety in tunnels, crowds and lastly planes. What I have tried to do is work through it by exposure. I love to travel and I do not want to limit myself from experiencing some great locations due to a phobia. This applies to flying and taking elevators. So, at some points I'd say within the last ten years, I purposely expose myself to these experiences and just learn to deal with it.
When it comes to flying, my triggers are very similar (if not the same as) to what many posters have already mentioned. I feel this anxiety while waiting in the gate area as well. That wait time before boarding can be very stressful. I am of the type that once I have the mindset to deal with my claustrophobia, I need to do I right away or else I may have the feeling of wanting to back out. So, sitting in the airport waiting to board is nerve-racking to me.
The next feeling comes when I step onto the jetway. That's the moment it hits me that I am about to intentionally put myself into the most uncomfortable position I could ever think of. My heart is racing right now, just thinking about it. I have learned to practice breathing exercises throughout the entire process (from the jetway until takeoff) and this has helped, as well as putting the vent directly on me.
The next moment when I feel that panic start to creep in is seeing the jetway fill up with passengers. I do like to board early so I can do my breathing exercises and become accustomed to the environment.
The next moment, like others have said, is right before I know they are about to close the door. But the odd thing is once the door is closed and I see the jetway moving, I know we are about to push back and move within the next 5 minutes and I feel ok. Once we're moving and heading toward the runway, preparing for taxi, and finally taking off and in the air, I am fine.
The final moment for me (and this is probably the worst) is when we land. As soon as we hit the ground, I am ready to get off the plane. The taxi to the gate is the slowest ride ever and when we finally arrive at the gate, that moment when the seatbelt sign goes off and I hear the pilot cut the engine (at least I assume that's what it is) and everybody stands up is complete and utter torture until that door opens. What I have done on some recent flights is go to the bathroom during those few minutes b/c it allows me the ability to move around and not stare out the window at the jetway longingly. What happens if I time it correctly is that by the time I come out of the bathroom, the door is just being opened.
I always fly in the first bulkhead row. Contrary to other claustrophobes, it's easier for me to not have rows and rows of people in front of me and with B6, that first row is always extra legroom. I do prefer a window seat as opposed to an aisle. Again, contrary to others, the aisle seat makes me feel more trapped. I also thought I preferred sitting on the same side of the plane as the exit door and jetway however, as I mentioned before, the jetway is the most anxiety-producing trigger for me. So possibly on my next flight, I might opt to sit opposite the door/jetway so I can't look through the window and see it.
Sad to say, flying first class, while great and the extra room was wonderful, I still felt sheer panic when we landed and the jetway had yet to connect to the plane. This was probably my worst episode ever. The first time they were delayed in even unlocking the jetway and on the return leg, the jetway malfunctioned and we had to go to another gate.
On a last note, depending on my destination, time of day and just overall feeling, I often will opt for an Ambien. I take it as soon as I board the plane and oftentimes, am asleep before takeoff. Other times I indulge in 2 Long Island Iced teas in the airport prior to boarding but that purpose is defeated when the flight winds up being delayed. When I'm flying first class, I drink the entire flight-no Ambien. My last two flights, I tried to go completely cold turkey from everything. It worked for the most part but when I felt some slight anxiety, I took 2 Benadryl and that helped to calm me.
I've also found flying early morning flights (when it's less chaotic) is beneficial.
Not sure if I was much help (especially with my long post) but hopefully this thread will provide some useful info for myself and others alike. I have at least 2 trips planned this year, so I need to keep pushing on to hopefully get over this phobia eventually.