Actual federal (FAA) jargon for the act of boarding an airplane. Leaving the plane (presumably in disgust at terms like this) is called deplanement.
The Transportation Security Administration is requiring that airlines
collect the September 11th Security Fee of $2.50 per enplanement, not to exceed $5.00 each way or $10.00 per round-trip ticket.
-- Continental Airlines message to frequent flyers, January 17, 2002
Let's teach new US residents to speak English -- but let's teach it to bureaucrats first.