Never in my wildest dreams would I have changed a diaper in the seat. I always fit just fine in there with her and still do (she's three) as I won't leave her in the seat alone and drag her with me or go with her when she needs to go. Okay, it was on descent and you're worried about turbulence, etc.- then wait until everyone is off the plain and THEN go and change him/her in the lav. It is just unbelievable that there are people who think this is okay.