Conclusions

6.1 Unlike birdstrikes, the aviation industry is only beginning to understand the risks of drone collisions. This study has resulted in an increase in knowledge in this area.

6.2 It is clear from the results that helicopter windscreens could be critically damaged by collisions with a drone in several realistic scenarios. It has also been shown that helicopter tail rotors can also be severely damaged.

6.3 Whilst more resilient than helicopters, the modelling and testing in this study has shown that airliner windscreens could be critically damaged by mid-air collisions with 4 kilogram class quadcopter components, and 3.5 kilogram class fixed-wing drones with exposed metallic components at high, but realistic speeds. These impact speeds would usually be encountered when the aircraft is at higher altitudes, 10,000 feet or above, but aircraft do sometimes operate at these speeds at lower altitudes.

6.4 The testing has also shown that the construction of a drone can make a significant difference in the impact of a collision. Where the toughest and densest drone components were covered with a plastic casing, or did not hit the windscreen first, the impact of the collisions was lessened.

6.5 With regard to the comparison with the severity of a birdstrike, it was realised that drones can cause significantly more damage than a bird of equivalent mass at the same speed. This seems to be due to the hard metallic components present in drones and means that birdstrike certification cannot necessarily be used as a prediction of complete protection from drones.