My daughter actually likes the airplane potty.  It's a chance to get out of her seat, walk down the aisle, smile at the flight attendants and hear how cute she is, maybe snag a snack, AND use the potty with the loud flushing noise. 

Despite the inherent fun in using an airplane bathroom, taking a child in the process of potty training on the plane can be nerve-wracking.   I always just got out the pull-ups to reduce overall stress.

When she was only mostly trained, she kept telling me she had to go.  Every 20 minutes. I'm not exaggerating there.   I put her in pull-ups while flying even when she was essentially trained, to reduce overall stress, but I had just spent months teaching her to tell me when she had to go — I couldn't ignore her.  I was so thankful that the man sitting in the aisle seat was a very understanding grandfather who had no problem getting up every 20 minutes. 

In fact, she likes the airplane potty so much that on our last flight, the worst happened.  She refused to use the potty before we left because she wanted to go on the plane.  I tried to talk her into going anyway, but she refused.   I waited until we got to the airport and asked her again.  Nope, she was waiting for the plane.  Once we got on the plane, I asked again.  Nope, she was waiting until the plane took off. 

As the plane was ascending, she fell asleep…and not surprisingly, she had an accident when she woke up.  I was very embarrassed!  After changing her clothes, I mopped up the seat as best I could.  I was still mortified and didn't know how to tell the flight attendants, but finally I got brave enough.  The attendant was so nice and reassuring about the whole thing:  it's not a big deal - they just switch out the seat when they land. 

Obviously you don't want an accident on the plane, but if it happens, it's no big deal.