Amazon Prime Air: How drones perform safe autonomous emergency landings

Amazon's delivery drones have to meet numerous safety requirements in the USA to be allowed to deliver parcels. These include the so-called Safe Contingent Landing (SCL), a type of emergency landing that the delivery drones can trigger themselves to bring about a controlled, safe landing in potentially dangerous situations.

During delivery flights with the MK30 drones and the successor MK30-2, the quadcopters operate at altitudes between around 35 and 122 meters. This allows them to fly over obstacles such as houses, trees and high-voltage power lines, while at the same time maintaining sufficient distance from conventional air traffic.

However, as the past has shown, problems can occur occasionally during flight, which can be caused by technical difficulties or external circumstances such as weather conditions. In most cases, Amazon's drones can react to such changes in external parameters and adapt their flight accordingly. In some cases, however, it may make sense to initiate an SCL in accordance with a structured procedure approved by the US Federal Aviation Administration (FAA).

Landing and recovery

The procedure involves the drone first transitioning smoothly from level flight to vertical flight only and then hovering in place. In the second step, the delivery drone uses its cameras and perception sensors, such as radar, to check the surroundings and search for a suitable landing site. This must be free of people, animals and objects. The landing site is evaluated in real time. Once a suitable landing site has been found, the drone initiates the landing maneuver while constantly monitoring the landing site.

Amazon's engineers have tested the landing procedure in simulations and real flights. They also tested hardship cases such as the failure of individual rotors and sensors. Thanks to partially redundant systems, the drone can maintain a controlled flight and initiate an emergency landing. Amazon also tested obstacle detection under difficult conditions to ensure that the drone can react independently to a blocked landing zone and find an alternative landing site.

After an emergency landing, the delivery drone notifies the control station so that the quadcopter can be recovered by an Amazon team. Amazon explains in an article that the rights of local residents and the community are respected, for example if a private property needs to be entered. In such cases, the members of the recovery team contact the owners and discuss the recovery process with them.

After recovery, the Amazon employees take the drone to the base for a full inspection. Only then is the drone released for flight operations again. According to Amazon, the FAA requirements were also considered during this release process.

(olb)