Although an autothrust system can significantly alleviate pilot workload throughout various flight phases, there are associated liabilities that may lead to an undesired flight profile or aircraft state. This risk is particularly heightened when the autothrust system is not utilized in accordance with the manufacturer’s recommendations or when pilots have an incomplete or incorrect understanding of autothrust and its integration with other aircraft systems and components.

Examples/Lessons:

1. Numerous autothrust systems incorporate height information from the radio altimeter to prompt idle thrust at the appropriate moment during the landing sequence. However, erroneous radio altimeter input during another flight phase could lead to an unintended and potentially catastrophic reduction in thrust.
2. An incomplete understanding or inappropriate selection of flight director autopilot modes could lead to an autothrust system response that deviates from expectations. This could result in the aircraft entering either a low-speed or high-speed regime unexpectedly.
3. Many manufacturers recommend selecting a specific flight director autopilot mode or disconnecting the autothrust system when encountering moderate or greater turbulence. Failure to comply with these recommendations can result in substantial airspeed excursions.

This list of examples is not exhaustive. Stay alert and fly safe.