AFM 4-2
Manual Deep-Stall
A manual deep-stall is when the safety pilot is in control and decides when and where the aircraft will
deep-stall.
An auto deep-stall will always pick the wind approach path, but manually the user must plan the path
to be into the wind. This can be done with waypoints or using guided mode to dynamically move the
aircraft. A manual deep-stall approach is typically done from 60-90 meters AGL. Always consider
surrounding obstacles. Typically, a higher entry altitude will be more difficult to judge for landing spot
accuracy, but it will give you more time to react or abort.
Activating the deep-stall switch on the handheld transmitter will do the following:
Override the autopilot regardless of what the previous flight mode was allowing the safety
pilot to steer
Disable motor output (although the propeller may continue to windmill from air flow)
Deflect the stabilator upward to approximately 45 degrees causing the aircraft to initially pitch
up and then settle
While a deep-stall landing is quite stable by itself, the safety pilot will need to maintain the desired
direction by steering with the right stick (rudder) on the handheld transmitter. The safety pilot is
steering to maintain a flight path into the wind and to aim at the desired landing area. The rudder is
the only flight surface that can be moved during a deep-stall.
Deep-Stall Abort
Both auto and manual deep-stall landings may be aborted during the approach or after the aircraft
has stalled. The most common reason for aborting would be a manual landing whereby the safety
pilot misjudged an entry and will thus overshoot or undershoot the landing area. Aborting below 30
meters may result in aircraft damage because the initial pitch down causes a loss of altitude.
An auto deep-stall abort commanded with the GCS will cause the aircraft to climb straight out until it
reaches the entry altitude, at which point it will restart the landing sequence.
A manual deep-stall abort is done by disengaging the deep-stall switch on the handheld transmitter.
Aborting will cause the aircraft to resume the flight mode it was in before starting the landing. For
example, a deep-stall from guided will return to guided if the deep-stall was aborted. If the aircraft
was in manual before the deep-stall, the abort will require a manual recovery and the safety pilot to
resume flying the aircraft in manual.
Selecting a Landing Spot
Auto deep-stall has an expected accuracy of being within 30 meters of the target location, with an
average error of 17 meters. Almost all errors are along the final approach path, rather than side to
side errors. This will improve over time as improved autopilot code is released to better manage this.
An experienced pilot can do a manual deep-stall with an accuracy of 10 meters or better.
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