DUAS XX26 - 3x BMFA reports of Unintentional BVLOS (Beyond Visual Line of Sight) followed by loss of the Drone
Initial Report
Report A
| Please select all appropriate options from below. |
| The occurrence involved a high risk of injury to people The occurrence involved operating less than 50m from uninvolved people The unmanned aircraft flew beyond visual line of sight and was recovered |
| Give full details of the occurrence stating fully how it happened: |
| The model in question is a Freewing MIG29 EDF foam model with twin 80mm fans. It flies on 2 x 6S 6000mAh lipos. I have flown it many times and had already flown it once on the day of the occurrence with no issues. I had been flying the model for about 1/2 a normal flight so about 2 minutes. I flew along the XXX field at about 50 feet and pulled up over the field at the western end with the intension of turning left by rolling to the right, followed by a turn to the left. As I rolled the model stopped inverted, motors cut, and it entered a shallow glide slightly northwest in the direction of the motorway. The glide was stable, and I had no further control. The model disappeared over the tree line. After an extensive search in the field to the northwest of the XXX field, I took the decision to push through the bushes which line the top of the motorway embankment and when standing in the open I could see the model still inverted and under the Armco barrier on the opposite side of the motorway. There were no stopped cars or persons near the model. After returning to the flying field, I took the car around to the other side of the motorway and eventually recovered the model. As these high power EDF models do not have a very long flight time of around 3-4 minutes and this varies greatly depending on the use of throttle, I always fit a Spektrum energy sensor which indicates verbally how much energy in mAh I have used every 10 seconds of flight. Unfortunately, this sensor was supplied with two EC3 connectors and my lipos have EC5 connectors so I replace the two plugs and leads. I do this by removing the existing wires and connectors and using a commercially purchased lead assembly with 200mm of lead with a female EC5 on one end and a male EC5 on the other. I cut the black lead in the centre and solder in the current sensor. The female EC5 is then plugged into the ESC and the male into the Lipo connector. On recovery of the model i found that the positive wire in the male EC5 connector which forms part of the purchased lead had come loose due to a dry or poor solder joint. This caused the supply to the BEC to fail shutting down the radio and both fans. |
| Estimated distance from flight area (point of launch) to occurrence location |
| 400m |
Report B
| Please select all appropriate options from below. |
| The unmanned aircraft flew beyond visual line of sight and was recovered |
| Give full details of the occurrence stating fully how it happened: |
| Model Aircraft incident XXXX. Time 11.40am approx. Eight flight had previously been flown, and at take-off the met conditions were fine for flying. The model flew a circuit however; a bank of sea fog rapidly blew across the flying site. Pilot endeavoured to carry out a quick return and land as soon as possible but visual contact was lost. Accordingly, the pilot cut the power and made a note of the direction in which the model was last seen. The model was subsequently found in an empty horse paddock. There was no injury or damage to property. |
Report C
| Please select all appropriate options from below. |
| The unmanned aircraft flew beyond visual line of sight and was not found |
| Give full details of the occurrence stating fully how it happened: |
| 1.5m foam glider (e-flite Conscendo) entered updraft/thermal with S/W wind Approx 10-15mph) quickly became beyond line off site with control single loss. |
| Estimated distance from flight area (point of launch) to occurrence location |
| 1.5 kilometre |
CHIRP Comment
The Board had the following comments:
- Three reports with a common outcome between them: unintentional BVLOS
- From the first report it seems that there was one part that had been changed after purchase and this then required soldering. The aircraft had been flown several times and indeed once before on the day of the occurrence. Whilst the reporter doesn’t mention that a pre-flight check was or was not performed, it would seem advisable that regular checking the one part that had been changed would be advisable. This might have caught the cracked soldering.
- The second point to mention is that there must have been an element of luck involved in the aircraft not being run over by cars on the motorway or distracting a driver as it crossed over at what must have been a low altitude.
- The subsequent two reports have been the result of encountering weather that was difficult to predict in advance using commonly available Apps.
- BMFA continues to emphasise the Sun, Wind, Eventualities, Emergencies, Transmitter control and Site rules “SWEETS” protocols in its Members Handbook, to deal with these eventualities. A link to the BMFA website giving details of what the acronym SWEETS is all about, can be found here: https://handbook.bmfa.uk/13-general-model-safety
- It is also worth mentioning that although helpful, weather Apps can be inaccurate if they are not based on a local Met Station. Some Operators therefore look at several weather Apps and then try and interpolate what they think the weather will be at a particular location.
- The Board would also recommend adapting a methodology for model aircraft and Drones called the Radial Scan. It is a systematic way to monitor aircraft instruments, emphasizing the attitude indicator (AI) as the central reference point. The scan involves focusing on the AI, then quickly checking other primary instruments (like airspeed, altitude, heading) and returning to the AI to make necessary adjustments. This pattern is repeated, creating a radial or spoke like pattern of visual checks. It could be adopted for flying aircraft models or Drones and involve switching from looking at the controller and then back at the aircraft, improving the pilot’s ability to maintain Visual Line of Sight of the aircraft.