GPS Altitude Adjust
Click the ALT/ft label in the Aviation Panel to access the GPS Altitude screen.
The buttons allow quick correction of the GPS altitude by setting an adjustment value, INC. The GPS altitude is not for navigation. This feature helps keep the flight information consistent and helps the pilot detect discrepancies that could indicate problems. Click GPS for the raw (INC = 0) ALT. While flying level at an altitude that is a multiple of 100 ft, click +100 or -100 one or more times to round ALT up or down to agree with your altimeter. This does not necessarily add or subtract 100 ft to INC but adjusts it to round ALT to the next hundred foot mark. If an approach to a runway is selected and the aircraft is centered on real VASI lights, GS can be clicked for a rough adjustment to the current computed glideslope altitude. This is a technology demonstrator, not to be used by the pilot who is landing the plane. Before takeoff, click RWY to adjust the GPS altitude to the airport elevation in the database. To prevent erroneous use, RWY is not available when the aircraft is traveling at flying speeds.
Typically, after setting the RWY elevation, the ALT still agrees with the altimeter reading after a couple hours and altimeter settings from Air Traffic Controllers. If the INC is large or varies, check your altimeter setting. The atmosphere does not always closely follow the pressure model used in altimeters. For aircraft altitude separation, use the official pressure reading. Never set your altimeter to the GPS altitude.
