on NW / DL
I fly mostly on NW & DL metal.
The DL website specifically states that GPS can be used when other PEDs can be.
The NW website is a bit more vague in that it does not mention GPS specifically.
However, I've used my eTrex Vista Cx on numerous flts, both domestic and international with little or no problems. I did have 1 or 2 FA ask me about it, but nothing more.