"A student, who's livelihood requires that he spend alot of time on the road, asked our teacher [R' Y. Kaminetsky] what he should do with regard to davening Mincha while on the road.
Our teacher responded that he must find a place to park his car, either at a highway rest area or a shopping center, and to daven mincha while sitting in his car. Our teacher stressed that in such a situation there is no need to daven standing in public [or to do anything else that would arouse the curiousity of others], because that will result in him being unable to daven with the required kavanah.
Interesting side note: Regarding those who would daven in a public phone booth (I guess this is only referring to those visiting museums), R' Yaakov characteristically felt that that would be considered stealing from the phone company, because while he is davening others would be unable to use the phone."
(B'Michitzas Rabbeinu Pg. 58-59)
It seems from this that R'Y was of the opinion that it's better to daven sitting down in your seat than to daven in a way which would impede your kavana.
I wonder what he held about minyanim on an airplane? Not only does that have the same problem of everyone staring at you like you're a martian (non-El AL flights) which certainly affects kavanah, but that also - in 99.9% of the cases - inconveniences others, be they stewards, stewardesses or passengers who have the unfortunate luck of sitting in the back. I am confident
R'Y would rather that everyone davened in their seats.