Weatherman1126 said:
There is a problem with my Flight Simulator. When I set the auto pilot to a
whatever heading, It will display that on the heading indicator on the
heading gauge in the cockpit. However, when I open my GPS, the heading is
different. I hate this because it ends up in missed approaches and etc. I
still don't know which one is the correct heading. Does anyone else have this
problem?
The autopilot heading hold points the aircraft in the direction set. It
makes use of the gyrocompass, which knows which way the aircraft is
faceing but NOT which way it is moving. However, crosswinds will add a
sideways component to the aircraft's motion. If your aircraft is faceing
East and the wind is from the North you will actually be moving
East-South-East. The GPS calculates direction and rate of movement
(vertical AND horizontal) from two or more position readings, having no
way of determining attitude or which way the aircraft is faceing.
Course is a line through a position along a specified direction. A
position's bearing, the direction towards that point from your aircraft,
might not correspond to the autopilot's course setting. Think of the
course setting as seeking a specified corridor instead of a direct
flight towards the destination point.
Autopilot Heading Hold: Direction to point aircraft, but does not
account for wind drift.
Course / NAV Hold with VOR/NAV selected: Track the specified line to or
from a ground based radio beacon allowing for wind drift. Uses the radio
signals generated by the ground based beacon.
Course / NAV Hold with GPS selected: Track the specified line to some
point which may or may not correspond to the position of a ground based
beacon. Uses radio signals from constantly moving satellite beacons.
Also allows for wind drift. Use the GPS's vertical speed to destination
reading to set the autopilot's vertical speed setting. Become aware of
the destination field's minimum ceiling and visibility requirements and
make the actual landing manually using the available visual aids.
Whatever navigation you utilize, make sure your descent is well clear of
terain and any other obsticles like buildings and radio towers. There
are maps for many, but not all, airports showing safe approach routes
with altitude information. Some GPS units for aviation use make that
information available on their display with periodic database updates
through the manufacturer.
