7.2 Emergency & Abnormal Procedures

Abnormal Versus Emergency

An abnormal condition is a degraded or unexpected state that still allows controlled response. An emergency urgently threatens people, other aircraft, or control. The boundary can change quickly.

Use the aircraft’s manufacturer procedure, actual failsafe configuration, and site contingency plan. “Press RTH” is not universal: RTH can climb into airspace, cross people, pass behind an obstacle, or land at an occupied home point.

Loss of GNSS or Position Hold

A GNSS warning can cause drift or attitude-based control. If the control link remains:

• take manual control using visual attitude and orientation;
• reduce speed and create distance from people and obstacles;
• stop precision camera work;
• move toward a clear landing area; and
• land before workload or battery becomes critical.

Do not toggle modes without understanding them. Magnetic interference, poor satellite geometry, multipath, and sensor faults can look similar. Diagnose after landing.

Compass or Heading Anomaly

A compass warning, toilet-bowl motion, or unexpected yaw can corrupt automated navigation. Stop the task, maintain VLOS, avoid routes that depend on heading, and follow the guide. If stable control remains, land clear. Recalibrating in the same magnetically contaminated place is not an airborne diagnosis.

Lost Control Link

Before launch, know whether link loss causes hover, land, return-to-home, route continuation, or another action, and after what delay. Confirm home point and RTH height/path.

If the link is lost:

• scan the known aircraft area and use crew calls;
• follow the manufacturer’s reconnection procedure;
• expect the configured failsafe rather than guessing;
• keep people away from the predicted route and landing area; and
• notify relevant persons if containment fails.

Choose the failsafe before take-off so its route avoids people, obstacles, and controlled airspace.

Low Battery or Power Anomaly

Battery percentage is an estimate. Cold, age, payload, wind, cell imbalance, and voltage sag can trigger earlier warnings.

At an unexpected warning, stop the task, use the shortest safe path to a clear landing, avoid a long return across people, land with reserve, and quarantine a hot, swollen, impacted, or abnormal battery.

A forced landing in an empty contingency area is better than an attempt to reach home across a pavement.

Propulsion, Vibration, or Structural Damage

Unusual noise, severe vibration, motor warning, or visible damage can precede loss of control. Reduce demand, avoid people, and land as soon as practicable at a clear location. A fixed wing must retain airspeed and use its forced-landing area. Do not perform aggressive airborne tests.

After landing, disarm, isolate power, inspect, and ground the aircraft until corrected and verified.

Flyaway or Uncommanded Flight

A flyaway is sustained uncommanded motion or inability to produce the expected path. Causes include orientation error, wind, link problems, GNSS/compass faults, wrong mode, or configuration.

Respond by identifying whether inputs work; selecting only a known appropriate mode; using visual orientation and creating distance from people; attempting safe landing or an approved termination method; and warning people without abandoning aircraft control.

Do not chase the aircraft physically while losing the airspace scan. Preserve logs and report as applicable if containment fails.

People Intrusion and Manned Aircraft

When a person enters the buffer, move laterally to restore horizontal distance or land clear. Do not count a climb as horizontal distance and do not overfly.

For a manned-aircraft conflict, give way immediately. Descend or land when safe, maintain the scan, and do not rely on the crew seeing the UAS.

Do not fly close to or inside an active emergency-response area unless the responsible service has given permission. Helicopters can arrive quickly at low level.

Fire, Crash, and Injury

After a crash:

• protect life and call emergency services when needed;
• do not touch a burning or venting lithium battery without protection;
• keep people away from wreckage and fire;
• disconnect power only if safe;
• preserve the site and evidence except for safety, rescue, or authorised movement; and
• notify the operator and use applicable AAIB and CAA routes.

A damaged battery can ignite later. Isolate it safely and follow manufacturer, emergency-service, and disposal guidance.

Scenario Matrix

Practise decision sequences safely in A3 training. Simulate faults rather than creating hazards. Competence is recognising the state, applying the right procedure, and preventing exposure to people.