You might find that it is not as bad as you thought.
I have been very lucky when I have traveled by plane with my babies as neither has ever been troubled by the takeoff or landing.
Also I have found that the ambient motion and noise of the plane seems to make my babies very sleepy and they generally sleep for the majority of the flights.
When awake mine particularly enjoy being able to stand on my lap and be able to look around the plane, otherwise don't be afraid to get up and wander up and down the aisle to jog them along or rock them to sleep.
I have a belief that me remaining very calm helps as I think that babies will feed off your stresses.
I agree that you should take lots of food/milk etc, in fact everything you can think off that might be necessary.
And don't do what I did last time we flew, when DS2 was 5mths (thankfully only a flight to Inverness) and get flustered at security after making the scanner bleep and then having to take off shoes etc and for me, and both DS's get patted down by scary security staff,
so flustered that we managed to leave the silly clear plastic bag containing DS's bottle of formula, and pouches of baby food, which we didn't realise until we were on the aircraft!
So do your best to stay calm and rational even before you get on the flight.