What are the risks of flying with a kid that has otitis media with effusion?

And what can you do to prevent these problems?

The kid is 1 year old and has never experimented accute otitis.
The possible OME was discovered by practicing a timpanometry.

It's difficult to predict. Theoretically, with pressurized aircraft any pain should be minimal, but I suspect many of us have experienced intense ear pain when we flew with a head cold.

Tympanometry can be very sensitive. The question is whether the infant's eustachean tubes are open. If they are, you should have little problem. If the infant starts to fuss - typically as the plane descends - give him or her a drink from a bottle or sippy cup. Swallowing assists pressure equalization in the middle ear.

Pain is the major risk. I personally never experienced a patient with a ruptured ear drum from this, although it can happen in theory. Even then, the perforation almost always heals without intervention.

main risk and inevitable is pain...which will be worse on "re-compression" ie descending. other risk is of perforation of ear drum...not uncommon in kids with ear infections anywy and although temporarily painful heals up ok. repeated events can lead to scarring of ear drum and hearing loss...but pretty rare....go on holiday, take some nurofen

Could be very painful with the added pressure from the plane.
Could ( very unlikely ) cause a rupture.