We used to strap our daughter into a car child seat and then into the aircraft using the seat belt - and ensured that she wore ear defenders.
We had a number of enjoyable days out and found that she more often than not fell asleep, but was never ill.
Flights were limited to around an hour.
Flew to Cark and visited Holker Hall - the man on the gate looked sideways as we pushed the buggy (with no car) - particularly when we said we had come from Manchester!
Flew to Wellesbourne and had a good day in Stratford.
Flew to Skegness for a fly-in (that won't happen again).
Flew to Caernarfon for the day.
All good fun.
KR
FOK