I did this last year at MAD, when it was obvious I was going to spend forever on a dodgy RJ-100 with no AC in the middle of summer. As I thought I knew the drill I insisted in getting off and having the crew check availability on the next flight to LHR (unfortunately no more flights that day to LCY my original destination). I was driven back to the terminal and my ticket was sorted out at the gate for the LHR flight (I even had time to nip back into the lounge if I chose to). I felt extremely smug as my flight departed the gate and the remaining PAX on the RJ were disembarking onto a bus, presumably to argue about the few remaining seats back to London on a Friday evening.

The lesson of this for me is to ask the crew to check alternative flights and seek a change of flight whilst embroiled in a delay and once another seat has been confirmed get off the original flight ASAP.

I have been involved in delays on 747s with both VS and BA which lasted around 2 hours and where the flights subsequently took off, but it seems the probability of a problem being successfully resolved is outweighed by the certain hassle of securing a seat on an altermative flight once the whole aircraft has deboarded.