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20th August 2023

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Loss of Visual Contact (BMFA)

Initial Report

We are grateful to the BMFA that they have now established a system whereby we automatically receive incident reports as they are filed. The occurrence happened above 400ft (120m) and the unmanned aircraft flew beyond visual line of sight and was not found.

The Model was an EFlite Mystique RES glider, flying weight ~5lb, wingspan 2.9m. Conditions were clear blue sky with small patchy clouds, wind from NE around 8mph gusting 15mph? I had climbed to ~500 ft and was circling in what I believed was lift centred over the flying patch. My telemetry was reporting current height just over 700 ft when the glider suddenly became indistinct and then totally disappeared against what I had taken to be a clear blue sky. After a few seconds of panic, I activated the spoilers and held in rudder, but the model did not reappear.

The next height report (30 seconds after the 700+ ft) was 79ft but I did not see or hear anything impact nearby and was concerned that the model actually carried on climbing and that the 79ft was a false reading. If the model had lost 700ft in 30 seconds, I would have expected to hear wing flutter on this model and then the noise of an impact. I did not see the model again and the telemetry lost connection. About 30 minutes later on, I drove downwind along the road for ½ mile or so, but the model did not reconnect with the Tx, so I have no idea where it may have ended up.

CHIRP Comment

The consistency of reporting amongst modellers is excellent and almost certainly better than the Drone community. We do note a relatively high frequency of unintentional BVLOS flight that sometimes ends with the loss of the aircraft. An important point to note is that before you take off it is always useful to run through in your mind what actions you will take should you lose sight of your aircraft. The BMFA have recently updated guidance on this and suggest considering following the ‘SWEETS’ pre-flight checks that we think have relevance to drone operations and are worth considering.

When unintentional BVLOS happens to drone pilots, the fact that they often have controllers with screens and the aircraft mostly have cameras, FPV or otherwise, the occasions when the aircraft is recovered may be slightly higher.

Gliders are famously difficult to spot from a crewed aviation perspective largely because of their profile. Clearly this is also the case as far as models (and drones) are concerned. A blue sky with small patchy clouds is a difficult environment to fly in if the aircraft has a low profile and is as far away as 700ft. The orientation of its flight may be even more difficult if the aircraft is circling. We wonder whether a strobe would make any difference, or perhaps painting the aircraft in a more visible colour?