In-flight upgrades
 

I read in this thread

http://www.flyertalk.com/forum/showp...60&postcount=4

that after the cabin doors are closed, upgrades aren't normally done. Is this true?

I remember once as a kid I was bumped from Y to J on Gulf Air because the flight was overbooked, then op-upped in-flight to F (ahhh, the double upgrade!) because of dripping water from the air vents above.

Also, I have recently been op-upped in-flight J to F on a British Airways TATL because my EmPower jack wasn't working and my seat got stuck.

The policies on upgrading vary among carriers. Many if not most U.S. carriers don't allow upgrades after the door has closed except for irregular operations that make the booked seat unusable with no other choices in the booked cabin available. Sometimes the flight deck has to approve such moves once the flight has pushed-back.

You can upgrade on SQ anytime during the flight as long as you have a credit card ready to pay the difference in fares between the two classes. The charge is processed through the same system used to process duty-free shopping charges. I'm not sure how the amount is determined, though.