I flew two of my DD's friends on two different trips this year (both age 11). I called JetBlue ahead of time and they advised me to get a notarized letter from each child's parents allowing me to travel with their children on the specified dates, along with written authorization to act as their guardian in case of medical emergency, as well as a copy of the parent's insurance card. It only took a few minutes both times and we all felt better knowing that if something happened, I could take care of it without a hassle. I had the letters with me at the airport but they did not ask the kids anything other than their names. It's worth the extra trouble in my opinion. You never know what can happen with kids.