Yes, the phone was one - I just had it on flight mode most of the time. I was also using it to take pictures all the way up.
The battery lasted all the way up and down.
The main drain on any phone is the cellular radio - so as long as you put it in flight mode, you're golden.
Most navigation aps only need GPS, which will still work in flight mode. Just make sure your wifi is also off.
And don't forget to download the relevant map at home before you leave!
