Date:	Monday 25 March 2019
Time:	14:44
Type:	DJI Inspire 2
Owner/operator:	Private
Registration:	Unregistered
MSN:	095XDAX002027D
Fatalities:	Fatalities: 0 / Occupants: 0
Other fatalities:	0
Aircraft damage:	Destroyed
Location:	Staple Hill, Chobham Common, Chobham, Surrey KT16 0ED -   United Kingdom
Phase:	En route
Nature:	Survey
Departure airport:	Staple Hill, Chobham Common, Chobham, Surrey KT16 0ED
Destination airport:	Staple Hill, Chobham Common, Chobham, Surrey KT16 0ED
Confidence Rating:	Information verified through data from accident investigation authorities

Narrative:
AAIB investigation to DJI Inspire 2 (UAS, registration n/a): Loss of control, Staple Hill, Chobham Common, Chobham, Surrey KT16 0ED, 25 March 2019. The AAIB Final Report was published on 14 November 2019, and the following is an excerpt from it:

"The operator was conducting a surveillance operation of a heathland fire utilising a DJI Inspire 2 which was able to stream footage to observers on the ground. Prior to the flight the operator’s standard checklist was followed to check the aircraft ready for flight. Two successful flights were completed with no incident. Between each flight the pilot changed the battery, which is known as a ‘warm start’.

During the third flight, the DJI Inspire 2 ascended to 365 ft whilst travelling in a south eastern direction from the Take-Off and Landing Site (TOLS). It then held station surveying the site 1,635 ft from the TOLS. Approximately four minutes later a decision was made to return the UAS to the TOLS so it could operate from a different location. As the aircraft returned it was seen to yaw suddenly to the right whilst rapidly descending. The pilot attempted to regain control but did not get any response. Both the pilot and spotter shouted warnings to those in the vicinity of the falling aircraft. An observer who was not part of the operating team heard the warnings and took cover in undergrowth near-by.

The UAS crossed a road and struck the verge approximately 5 metres from him. Both the pilot and the spotter reported seeing an object fly off the aircraft moments before control was lost, they also heard a loud high pitch squeal as the UAS fell.

=Aircraft examination=
Examination of the UAS, by the operator, confirmed that all four propellers had been fitted correctly to their hubs, however of the eight propeller blades, only two remained intact and connected to the hubs. The remainder of the blades had fractured at or near to the propeller hubs. An examination of the fracture surfaces of the propeller blades was not made.

The investigation completed by the operator concluded that the likely cause of the accident was as a result of an inflight propeller blade failure, however a speed controller failure could not be ruled out.

=Analysis=
When a 'warm start' was carried out by the operator, there was no requirement for an inspection, similar to that completed prior to the first flight, to be done. It as considered that if an inspection had been carried out during each battery change a cracked propeller blade may have been detected.

=Safety actions/Recommendations=
As a result, the operator has taken the following safety action. During warm starts the operator has introduced physical checks, including an inspection of the propellers, before the next flight. The operator has also instructed its pilots not to overfly people

=Damage Sustained to Airframe=
According to the above AAIB report, the UAS was "Destroyed"

On March 25, 2019, a large fire swept through Chobham Common, which is the largest national nature reserve in the southeast of England. Wildlife workers discovered and reported the blaze around 11:30 GMT. Approximately 40 firefighters worked to tackle the fire, which covered an area of about 30 hectares (approximately 74 acres) of heathland

1. AAIB Final Report: https://assets.publishing.service.gov.uk/media/5f4628d4e90e074c4ea3c61e/DJI_Inspire_2_UAS_250319_11-19.pdf
2. https://www.dji.com/uk/inspire-2
3. https://www.surreywildlifetrust.org/nature-reserves/chobham-common
4. https://www.bbc.co.uk/news/uk-england-surrey-47705627
5. https://www.getsurrey.co.uk/news/surrey-news/large-fire-chobham-common-sets-16023580
6. https://www.getsurrey.co.uk/news/surrey-news/gallery/incredible-pictures-chobham-common-fire-16026099
7. https://www.getreading.co.uk/news/uk-world-news/large-fire-chobham-common-sets-16023932
8. https://www.countryfile.com/news/chobham-common-wildfire-destroys-vital-wildlife-habitat
9. https://en.wikipedia.org/wiki/Chobham_Common

Drone (UAV) camera footage at Chobham Common 25 March 2019

Date/time	Contributor	Updates
29-Jun-2021 18:32	Dr. John Smith	Added
17-Aug-2024 06:18	Dr. John Smith	Updated [Location, Departure airport, Destination airport, Source, Embed code, Narrative, Category, ]