Some say to pray in one's seat.

Citations:

* http://www.vosizneias.com/43425/2009/11/19/manchester-uk-rabbi-dont-pray-with-minyan-on-a-plane/
* http://www.vosizneias.com/61173/2010/07/30/israel-rabbi-on-planes-shemoneh-esra-prayer-can-be-said-sitting-down/