Originally Posted by
IO540
The Garmin 496 GPS-derived altitude is a helluva lot more accurate than an altimeter, especially with EGNOS.
Especially if you don't quite know the QNH for the place you are going to
Garmin's GPS will give you geopotential altitude, which is best for terrain avoidance, although non-conservative. RPS is more conservative.
It will not give you pressure altitude, which you need for quadrantial/semicircular rule, it will not give you separation from controlled airspace, and it will not have you using the same reference as anything else out there that may fly into you.
Incidentally you said earlier that I didn't mean IMC capability on some VFR flights wihout a clear horizon, I actually meant radio navigation capability. Nope, I meant what I said - loss of attitude information will kill me quite quickly, loss of positional awareness VFR will take until I run out of fuel and whilst it's a very good thing to know where I am, it's a much better thing to know which way is up.
G