And, wind up with a 5-figure lawsuit to defend?

Presumably in the UK, which has loser pays (so easier to defend and win against nuisance suits), in which case BA would simply argue, successfully, that the passenger said he/she didn't want to fly and wanted to get off the plane, and BA met his/her request.

It Surely Is
 

a judgement call on the part of the crew. Floridly psychotic person on the plane, no way. And I say that as a person who works daily with psychotic people.

Panic attack lady may be different. As a person who is afraid to fly and flies medicated, I've noticed in me and by the comments here that pushback can be the worst time for some people. Teaching the crew how to deal with panic attacks and talking to the person to see if they know how they experience a panic attack could guide the crew into making a decision and maybe avoiding having to return to the gate in the case of anxiety. At least some of the time. Ideally, the FAs would have a drawer full of Klonopin, but that ain't gonna happen.

And yes, if people know that they get anxious when they fly, or might, they do have some responsibility in making sure they do what they can to avoid having the aircraft have to return to the gate.

I was flying DTW-CDG and sat next to an anxious woman who seemed fine until we passed Newfoundland and completely came unglued. Rocked back and forth in her seat, crying, saying "I don't want to drown if we crash, I don't want to drown if we crash." I'm an ER/Trauma nurse and I deal with people who have anxiety attacks all the time and it really sort of annoyed me that I had to deal with one on a transatlantic flight. I asked her if she had any anti-anxiety meds on her. She did but of course they were in her checked bags. Who does that? I just looked at her and said,"Well the good thing is if we crash you'll be dead when we hit the water so you won't need to worry about drowning. Why don't you pull down the shade, listen to some nice calming music and pull yourself together or this is going to be an awfully long flight for both of us." I offered her my Bose noise cancelling headphones so she wouldn't be overdramatic at the various sounds of flight. She followed my advice and in 20 minutes she was snoozing.

Those prone to anxiety really need to pre-plan to have their meds on them (and not in their checked bags) and if they're terrified to fly, then DON'T. Its awfully rude to inconvenience others because of your illness. If I had a stomach virus and was vomiting, I wouldn't think twice about not flying.

Having worked in an MRI suite, I've seen plenty of panic attacks occur. Sometimes it was completely shocking who had trouble with it. I've seen people who worked in mines, wells, and shafts completely lose it in the MRI tube but were fine being in other confined spaces. This was their first time ever having a panic attack.

I would hope that this was the pax's first attack. Otherwise, I'm with everyone else -- know your limitations and plan ahead. Get blitzed at the airport bar like the rest of us do before a long flight.

Don't make me pull this plane over right now!

Anyone with a medical condition should take their meds. I do. If you can't handle a plane ride with meds, don't get on a plane.