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Old Jul 10, 2011, 08:56 AM
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My other plane flies itself..
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Joined Jul 2011
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Originally Posted by tridge View Post
Our team has a question about the interpretation of the 3rd bullet in section 5.6, Flight Termination. We see the words "OVERRIDING any other onboard system" as still allowing for override by the pilot on the ground, using manual RC control, but that depends on the interpretation of "onboard system", so we would like to get confirmation that our interpretation is OK.

The reason we interpret it this way is twofold. First, we think that allowing for RC override while in visual range increases safety. For example, if a geofencing error occurs in the autopilot while it is still over the airfield then allowing for the pilot to try to bring the plane down well away from spectators seems like a safer option. This would only happen when the plane is in visual range, and the pilot judges that manually overriding using the RC transmitter is the safest course of action.

The second reason we think this interpretation is probably the right one is that we noticed that the block diagram of the Millswood failsafe device shows that RC override is possible even after flight termination is activated (the RC mux is the last mux in the chain). I think the Millswood device was given the OK in previous challenges, so that seems to support the interpretation that RC override is allowed.

Can you confirm that "onboard system" does not exclude the possibility of RC pilot manual override in case flight termination is activated?
Hi all,

just wondering if an official statement on the above has been received, as we have a similar concern over the interpretation of 5.5.1.

For example, given:
  • "immediate activation of the flight termination mode" is required on
  • "Loss of GPS position AND Loss of Data Link" and that this
  • "must be met for both autonomous or manual flight modes"

a strict interpretation would imply that if the aircraft is within visual range and under manual RC (e.g. non-autonomous take-off), and for some reason suffers a GPS and data loss link (or autopilot lockup, or...) then the flight termination system should be engaged. Which doesn't seem likely to be the actual intent.

Like the quoted poster, our interpretation is (at least for platforms where SAS is not required) that within visual range that manual RC control take precedence over the flight termination system, both on the basis of increased safety (i.e. allowing judicious use of manual control when in visual range during what would otherwise be a flight termination condition) and simply on the mere existence of section 5.4 detailing the UAV controller overrride.

Nevertheless, that specific use of "manual" in "must be met for both autonomous or manual flight modes" in section 5.5.1 remains a little incongruous to us, and as such an official clarification as to whether or not FTS takes precedence over manual control in all or selective cases would be appreciated.

Claudio - Team LOAF UAV
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