brought in the GPS error. Nevertheless, as the GPS altitude error is
usually less than 10 meters, it is safe to apply it on a 30m or a higher
altitude of L4 / L3.
3. The plane maintains an (initial) SCAN RUNWAY ALT (25 meters in this
example) and flies over the runway. This SCAN RUNWAY ALT parameter
is added to the ASL of point L1. For example when you record L1 (or
upload from the GroundStation), the ASL of L1 is 90m.In this example
the plane will try to scan the runway at 90+25=115m ASL altitude.
The Flight controller will fly to 115 meters altitude according to the GPS
data. Due to possible GPS altitude error, scanning runway altitude
should not be set too low to prevent from crashing on the first attempt.
It is generally recommended to set an initial scanning runway altitude at
about 25 meters. In the worst case even if the GPS altitude error is 10
meters, it is still quite safe. If you expect the battery to retain enough
juice by the time of landing, you can define a higher SCAN RUNWAY ALT
and allow more scan times.
3. When the plane flies over L1, and if the laser altimeter gets a valid
reading, this altitude reading is immediately used to calibrate the
barometer, and GPS no longer plays a role in altitude estimation. The
plane engages a standard landing procedure. After having been
calibrated by the laser altimeter, barometric measurements are
