In this litgious age, I can't blame some airlines for not allowing the use of GPS devices while underway. Having said that, my Etrex Cx meets the requirements of 47 CFR Part 15-B, as does my laptop. Yet, I can use my laptop onboard commercial aircraft, but not my Etrex.
http://en.wikipedia.org/wiki/Part_15_(FCC_...ional_radiators
Garmin also says that my Etrex meets EN 55022:1998, EN 61000-3-2, and EN 60950-2:2001, which my laptop doesn't even meet.