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RPIC Station AE Manual
4. Emergency And Abnormal Procedures
Emergency Procedures
Link Loss (LTE)

Link Loss (LTE)

Andi Lamprecht Andi Lamprecht ·· 3 min read· Draft
Link Loss (LTE)
WARNING: If link is lost or degraded the aircraft will enter an automated Return to Home maneuver. Due to lack of RPIC control this may result in damage to unmanned aircraft or significant damage to persons, properties or critical infrastructure (MINOR)

INDICATIONS

  1. Uncrew announces “C2 Lost”, Red aircraft indicator
  2. AMC announces “Communication Lost”
  3. Stale Telemetry, aircraft position no longer updating on GCS display

POSSIBLE CAUSES

  1. Signal degradation
  2. Hardware failure
  3. Server failure

FAILSAFE BEHAVIOR

If link is lost or degraded and communication with the Uncrew server is lost, the onboard Uncrew application uses built-in logic to safely return the aircraft to the home point. When the application detects a loss of comms with the Uncrew server, it waits 45 seconds for communication to be regained.

After 45 seconds of lost comms, the onboard application checks the winch status. If the winch is locked, the system commands a Return to Home. If the winch is not locked, the onboard application waits an additional 30 seconds to allow the winch delivery to complete. After 75 seconds total, if the winch remains unlocked, the system sends a retract command to the winch. The onboard application then waits another 30 seconds to allow the winch to fully retract and lock. If the winch still is not locked after a total of 105 seconds from the initial loss of comms, the system sends an unspool command and initiates Return to Home.

When the FMU loses communication with the Skynode while in Mission or Hold flight mode, the PX4 autopilot engages a Return to Launch (RTL) failsafe using the previously planned mission path, after a loss timeout period of five (5) seconds.

PROCEDURE

LOSS OF LTE ANNOUNCE

The RPIC is to announce over voice comms “Loss of LTE” once emergency conditions are identified using the indications information above.

RPIC/VO(s): Aircraft VERIFY

The RPIC or Visual Observer shall confirm visually that the aircraft is performing the Return to Home behavior.

Procedure Complete

If Return to Home fails:

Note battery/altitude/time/heading/speed, monitor for energy failsafe and prepare for recovery effort

The RPIC shall note the information above using the available last known telemetry seen within the Uncrew Mission Console on the RPIC Control Station.

Procedure Complete
NOTE: If connection with aircraft is regained, indicated by green Uncrew aircraft status indicator, continue to monitor telemetry.

If Link is Re-established:

Uncrew: Pause SELECT

To confirm aircraft command and control, select the “Pause” button in the Mission Console on the RPIC Control Station.

Uncrew: Return to Home SELECT

Select the “Return to Home” button in the Mission Console on the RPIC Control Station.

Return to Home Button

Once the button is selected, a popup window appears requiring RPIC confirmation. This window will remain displayed until “CONFIRM” is selected or exit (“x”) is pressed.

Return to Home Confirmation

Once the command is confirmed, the aircraft will stop performing the mission and begin navigating to the takeoff location. The aircraft will maintain its altitude at the defined desired altitude. Uncrew will navigate the aircraft so that all NFAs and perimeters are avoided. The Aircraft Status shall be Contingency.

At the takeoff location, the aircraft will land. Precision landing mode shall be automatically attempted during the landing sequence.

Procedure Complete
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Accelerometer FailureUncrew C2 Loss