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Your altimeter displays one altitude while your GPS displays another. Under VFR, which do you use/when?: Revision
Categories: Trike Talk, Equipment, Training / Learning to Fly a Trike, Safety, ATC & Communication, Cross Country / XC
"Under VFR, you should be flying at a cardinal altitude (odd or even thousand-foot altitudes e.g. 4,000, 5,000, 6,000, 7,000, etc.) plus 500 feet. This provides separation from IFR aircraft and other VFR aircraft on crossing courses.
Your altimeter displays Indicated Altitude and that is what you should always use (for traffic separation). Indicated altitude is pressure altitude corrected for local atmospheric conditions. The correction is done by entering the altimeter setting given by an Air Traffic Controller or an AWOS.
All aircraft in a given area should be on the same altimeter setting so relative (altitude) separation is maintained.
A GPS, on the other hand, measures your Absolute Altitude as it trilaterates between multiple satellites. While more accurate than pressure altitude, it does not provide the same relative separation from other aircraft."