We are flying to Mexico from Boston on 4/10 and we have just noticed that our 10 year old daughter's US passport is expired. She does have a valid French passport to travel on. I dont expect any issues going in to Mexico, but have concerns for the way back. I have applied for an ESTA indicating her dual citizenship and it got approved, so technically she has the paperwork to board the plane.
But I'm concerned that once the airline sees the rest of the family with either green cards (for me, me husband and our other daughter) or US passport for our son, they might ask why she is traveling on ESTA and deny her boarding if they realize she has an expired US passport.... I'm less concerned about immigration once in the US as we can prove her citizenship by showing the expired passport and they cannot deny her entry... Is there a big chance that american airlines might deny boarding??