My husband is a pilot and I used to be a flight attendant. There are tons of people scared of flying and it is understandable, especially in your daughters situation! Flying is actually very safe! It is much more dangerous to get into your car and drive somewhere. The bad thing about plane disasters is that they claim the lives of many, in one incident.
The one positive thing about accidents is that there are invistigations into every disaster and there are changes in policy and procedures, in the aircraft itself. After 9/11 every cockpit door was changed and countless procedures have changed. We watched a movie of United 93 the other night and I was shocked the pilots opened the door, even after getting a message of possible intrusion! That would never happen today. I think every person who is on a plane today is more watchful of their surroundings!
Flying will never be 100% safe, but neither will driving a car, or riding a bike. Know that the people flying the planes have families as well and will do anything and everything in their power to get you there safely.
I hope this was of some help to you. If you have any questions, please pass them along...from you or your daughter.