The UA fell from a height of about 70 ft into a pond when the emergency cut-out was accidentally operated by the pilot. The pilot stated he had not recognised the emergency cut-out function icon which had appeared on the flight controller screen. In attempting to clear it he unintentionally activated the function, stopping the UA motors.
History of the flight
The UAS was being used to search for a missing person in the area of a large pond surrounded by trees. The search was being conducted at night and was using a thermal camera to search areas hard to access by foot. The weather at the time was good with only a light breeze.
The UAS pilot reported that during the flight he became aware of a message on the screen of the flight controller which he did not recognise. He did not realise the message was a warning and attempted to clear it but in doing so the aircraft motors cut out, causing the UA to fall from a height of about 70 ft into the pond below.
The SkyRanger UAS includes a quadcopter UA powered by four electric motors with a
maximum takeoff weight of 3.5 kg. Using the DROPS analysis tool a dropped object of this weight is capable of causing fatal injuries to an individual wearing a hard hat from a
height of only 4 m.
The UA is controlled remotely by a pilot using a flight controller containing a small screen
to input commands and to receive information. A stylus has to be used to make selections on the screen.
The UAS has an emergency cut-out function which cuts power to all four UA motors. It is
accessed by holding the stylus over an icon on the flight controller screen showing a white aircraft on a black background. This causes the aircraft shadow under the icon to flash red. By tapping the icon three times within three seconds the emergency cut out function is activated.
Data from the UAS was sent to the manufacturer for analysis. This confirmed that the cut‑out screen icon had been activated three times within three seconds, causing all four electric motors on the UA to stop.
Two neighbouring police forces had combined the management and oversight of their UAS operations. Between them they operated a number of UAS with about 150 officers being qualified to use them.
In order to qualify as a UAS pilot, personnel were sent on a five-day course with a civilian
training company to gain the necessary CAA recognised qualification, during which time
they were required to fly a UA for a minimum of two hours. This was followed by further
internal training working alongside a more experienced qualified UAS pilot within the relevant police unit for a period of time until the trainee was considered ready for assessment.
This assessment was carried out by one of a small number of assessors within the two police forces.
The assessment covered various aspects of operating the UAS, including role-specific requirements and more general aircraft requirements.
The two police forces used a number of different types of UAS, including the SkyRanger.
Pilots operating the SkyRanger were required to undertake a two-day specific course,
designed by the manufacturer but run internally. The course included the management of
different aircraft warnings and failures, with pilots needing to pass an assessment at the end of the training.
Pilots were required to maintain a minimum currency, as required by the CAA, of two
hours flying in 90 days. Where they fell below this requirement pilots were required to be
re-assessed before they could operate again.
The pilot had completed his initial training in 2018 to gain his UAS pilot’s qualification. Due to an unexpected lack of availability of UAS in his police unit he had then not operated further until undertaking a SkyRanger course in February 2020. The pilot had passed his assessment with no apparent issues.
At the time of the accident, he had accumulated a total of 6 hours 15 minutes flying time, of which 4 hours 15 minutes were on the SkyRanger.
The pilot had not recognised the significance of the icon that he had inadvertently selected on the flight selector and his attempt to clear the message from the screen had
the unintended consequence of activating the emergency cut-out function. This had shut
down the motors and caused the UA to fall into the pond below.
CAA requirements currently allow a person with no previous experience to gain a
commercial UAS pilot’s qualification in a relatively short period of time, often in less than
a week. The high level of automation available also makes many UAS relatively easy to
These points have the benefit of making this important area of aviation more widely available.
They however also present the potential for people operating UAS to do
so without the benefit of the experience gained over the longer and more extensive training required for more traditional routes into manned aviation. Recent AAIB investigations reveal a lack of understanding by some UAS pilots of fundamental operational factors such as weather limitations and the handling of aircraft warnings and failures.
The potential for such UAs as that involved in this accident to cause serious or fatal
injuries when falling from even relatively low heights highlights the need for UAS pilots to
be capable of understanding all aspects of their operation. This in itself requires careful
management where an operator has a number of different pilots and systems under their
control, with a need to carry out effective training and assessments, as well as keeping
pilots properly current.
The police forces involved had been increasingly investing in the training and assessment of those officers using UAS. They were already in the process of introducing a new system of pilot assessment which will require pilots to undergo an assessment every six months, incorporating an annual day’s training. Since the accident, they have also allocated an officer working full time in the training role to compliment the assessors already in place.