We recently flew transatlantic with our 4 month-old son on a Virgin Atlantic flight.
The flight attendant kindly offered to warm our son's feeding bottle. She took the full bottle away and 15 minutes later, I went to find it because I was worried that it would be too hot. When I reached the galley, she handed the bottle back to me and I thanked her but said I'd been a bit worried because it had taken so long and I thought the bottle would have overheated. She replied that it had overheated but that she'd cooled it down. I asked how she'd cooled it and she said she'd added some cold milk - ordinary cow's milk. She didn't realise that baby's bottles do not contain plain cow's milk.
I explained what a bad idea that was and she was very apologetic. But please be careful if you have your kid's bottle warmed on a plane!