Unmanned Aerial Vehicle Crashes During Automated Landing Test

Casualties unknown • Runway 11, Andrew’s Field (FAAF), Western Cape, ZA

An Astus II UAV sustained substantial damage after conflicting control inputs from two pilots led to a loss of control during a test flight in the Western Cape.

What happened

On 19 November 2021, an Astus II unmanned aerial vehicle, registered ZT-UOI, was conducting a test flight at Andrew’s Field (FAAF) in the Western Cape. The mission, operated under Part 101 regulations, was intended to test automatic take-off and landing (ATOL) capabilities. The flight began with an automated departure from Runway 11, after which the aircraft maintained a loiter altitude of 600 feet.

During the landing phase, the aircraft transitioned from a high-accuracy Differential GPS lock to a less precise 3D GPS fix. As the UAV entered the flare phase approximately 5 feet above the ground, it began to yaw left and drift from the runway centerline. In an attempt to prevent a mishap, the safety pilot switched the aircraft from ATOL to manual mode to execute a go-around. However, shortly after, the internal pilot also attempted to intervene by switching the aircraft into Setpoint mode to initiate a similar go-around maneuver. This second command instructed the aircraft to pitch up without providing any guidance for banking.

The investigation

The investigation examined the flight operations and the control environment. It was noted that the safety pilot was positioned near the runway using a handheld transmitter, while the internal pilot operated from a container-based main controller. The two pilots were linked via an intercom system, but only one person could hold the communication channel at a time. The investigation also reviewed the aircraft's positioning accuracy, noting the shift from DGPS to a 3D GPS fix during the approach.

Findings

  • The primary cause of the accident was the loss of control resulting from conflicting control inputs between the internal pilot and the safety pilot during an abrupt maneuver.
  • A lack of effective communication between the two pilots regarding who held active control of the aircraft contributed to the error.
  • A crosswind from the right pushed the aircraft toward the left of the runway.
  • The aircraft's left wing struck nearby shrubs, causing it to flip and land inverted, resulting in substantial damage to the Astus II.

Probable cause

The aircraft lost control due to simultaneous, contradictory commands from the internal and safety pilots during a go-around attempt, exacerbated by poor communication and crosswind conditions.

Frequently asked questions

What happened in the 2021-11-19 Astus II Tellumet accident near Runway 11, Andrew’s Field (FAAF), Western Cape, ZA?

An Astus II UAV sustained substantial damage after conflicting control inputs from two pilots led to a loss of control during a test flight in the Western Cape.

What aircraft was involved and where did it happen?

The accident on 2021-11-19 involved a Astus II Tellumet, registration ZT-UOI, at Runway 11, Andrew’s Field (FAAF), Western Cape, ZA.

What was the probable cause of the accident?

The aircraft lost control due to simultaneous, contradictory commands from the internal and safety pilots during a go-around attempt, exacerbated by poor communication and crosswind conditions.

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