My daughter's first flight was at age 8 weeks when we flew LAX-RDU to house hunt for a move. She slept almost the entire way in my sling. She had a bottle, changed a diaper in the lav, and little cuddling and back to sleep. 3 months old is easy-peasy. For me the toughest was 3-4 years old. She's 7 now and an excellent traveller