Checkboard
not all models have GPS available, unfortunately.
shortfuel
yes, We have that tool in the bus, too, so you can keep flying safe within the envelope, but I mean i would like to have some alternative means of knowing if I am flying at zero V/S so I can use the tables according to my GW and set the pitch (which thrust as needed to maintain it) and then find which is the mother****er erroneus instrument. (It would be useful to realise that altitude information is misleading, too). In pitot only scenarios, everything is simple once you come to the conclusion that speed is unreliable.