I fly with Lucy monthly. We just returned from North Carolina. I've only flown Delta so far with her and the attitude is hit or miss...We were delayed 2 1/2 hours coming home and she was out of the carrier on my lap in the terminal the entire time. Everyone loved her including the attendants who were waiting for our flight to board. I was lucky enough to get upgraded and took Lucy out as soon as possible and had her in my lap. The First Class attendant had no problem with it but then a steward (man) from the back came up front for something and told me I had to "bag it and zip it". I did, but kept her in my lap. When he was gone the attendant came by and told me it was okay to take her out again...lol.
I'm one of the lucky ones with Lucy. She can fly all day and have no problems. The only time she whined was when she had to potty so I took her to the bathroom, put a pad on the floor and she went and that was that.
On the off topic of children - C'mon, of course it is agitating to hear a crying baby/child but they are children-out of their element and comfort zone and if a parent had to guarantee their child wouldn't make a peep they would not be able to go anywhere by air

The topic of out of control children/parents could have it's own thread with many responses I'm sure!