No - that's not correct. There is no catastrophic event recorded in the log,
The log file wouldn't log a loss of power - because there's no power for the CPU to create a log.
and the downlink signal strength clearly decreases to zero over the flight path from 300 and 550 m, not even close to instantaneously as would be expected from a catastrophic failure.
While I concede that the drone may have lost signal (which is strange from only 1500' away), I still hold firm the assertion that the gradual loss of downlink signal does NOT mean the drone crashed. It's not uncommon to lose signal during waypoint missions, albeit, odd that it would lose signal @ only 1500'. But even then, the drone was clearly ascending to match the terrain. One must assume that the drone continued to maintain its clearance over the trees. While I concede that 158' isn't a lot of net altitude, it should've been enough to clear the trees in that area.
If you look at the waypoint mission, the drone was on a fairly aggressive ascent from WP2 (24 meters) to WP3 (to roughly 95 meters). This is consistent with the log files that show the drone ascending, right up to the point it lost connection @ 208' AGL. WP1 seems erroneous to me, and should probably be tossed aside. So....unless we have reason to believe that the drone leveled off (which would directly conflict with the log files) or hit a tower, we can only assume that it continued its ascent, thus clearing all natural objects (trees).
The uplink signal strength also decreases steadily, but the record does not show it going to zero. Why the signal was so poor at relatively short distance is unclear, but the steady decrease in uplink and downlink almost completely rules out a catastrophic cause for the downlink loss,
I disagree. I see no reason, other than catastrophic failure, why the uplink would end so abruptly. A power loss would explain why the log just ends while we still have uplink signal. Remember, "downlink" is the signal used to control the bird. "Uplink" is the telemetry data. So, in theory, as long as the bird still has an uplink connection, the iPad should have continued to generate a log. We never see a complete loss of uplink signal. We simply see the log file end abruptly. This screams "power failure" to me. If there were 15-story buildings around, I would've guessed that the drone crashed into a building. I lieu of buildings or other tall structures, power loss seems the most likely scenario.
and there is no reason at all to suppose that the aircraft crashed at the point of downlink loss.
Agreed. Downlink is for control. Uplink is video and telemetry data. A catastrophic event is the *only* reason why we'd see the log file end while we still had uplink signal. The abrupt end to the log file while still essentially connected makes me believe that the loss of signal was due to a catastrophic event.
There is also nothing to suggest that the aircraft did not continue on its Litchi mission after downlink loss.
Agreed. But worth noting, had the drone *not* crashed, we would see a *gradual* loss of uplink signal to mach the gradual loss of downlink signal. We didn't see that. Uplink signal ends abruptly, indicating a catastrophic event.
If it did continue then it most likely ran into obstacles around WP2, since its programmed ground clearance was only 24 m at that point.
This is what makes zero sense to me. We have an inconsistency in data. According to the log file, the vehicle ascended to 158' directly, and then moved on to the next waypoint, constantly ascending as it moved horizontally. But according to the waypoint *graph*, the vehicle STARTS @ 64 meters and DESCENDS to 24 meters. I don't know where that waypoint graph came from or what it's basing its altitude curve on, but it completely conflicts with the log file data. I would dismiss it.
In summary, your safe bets and firm conclusions all appear to me to be based on assumptions that are entirely unsupported by the data...
I disagree. A gradual loss of downlink signal is natural. An uplink signal loss would follow the same curve. Instead, we see an abrupt halt in the log file while we still have uplink signal. To me, that says "catastrophic event."
No - that's not correct. There is no catastrophic event recorded in the log,
The log file wouldn't log a loss of power - because there's no power for the CPU to create a log.
and the downlink signal strength clearly decreases to zero over the flight path from 300 and 550 m, not even close to instantaneously as would be expected from a catastrophic failure.
Agreed. I concede that the drone gradually lost downlink signal (which is strange from only 1500' away). But it's not uncommon to lose signal during waypoint missions, albeit, odd that it would lose signal @ 1500' out. But worth noting is that the drone clearly ascended to match the terrain. So one must conclude that the drone continued to maintain its clearance over the trees. While I concede that 158' isn't a lot of net altitude, it should've been enough to clear the trees in that area.
If you look at the waypoint mission, the drone was on a fairly aggressive ascent from WP2 (24 meters) to WP3 (to roughly 95 meters). This is consistent with the log files that show the drone ascending, right up to the point it lost connection @ 208' AGL. So....unless we have reason to believe that the drone leveled off or hit a tower, we can only assume that it continued its ascent, thus clearing all natural objects. WP1 makes zero sense to me. According to the log files, the drone never ascended from 64m to 24m.
The uplink signal strength also decreases steadily, but the record does not show it going to zero. Why the signal was so poor at relatively short distance is unclear, but the steady decrease in uplink and downlink almost completely rules out a catastrophic cause for the downlink loss,
I disagree. I see no reason, other than catastrophic failure, why the uplink would end so abruptly. A power loss would explain why the log just ends while we still have uplink signal. Remember, "downlink" is the signal used to control the bird. "Uplink" is the telemetry data. So, in theory, as long as the bird still has an uplink connection, the iPad should have continued to generate a log. We never see a complete loss of uplink signal. We simply see the log file end abruptly. This screams "power failure" to me. If there were 15-story buildings around, I would've guessed that the drone crashed into a building. I lieu of buildings or other tall structures, power loss seems the most likely scenario.
and there is no reason at all to suppose that the aircraft crashed at the point of downlink loss.
Agreed. That said, a catastrophic event is the *only* reason why we'd see the log file end while we still had uplink signal. The abrupt end to the log file while still essentially connected makes me believe that the loss of signal was due to a catastrophic event.
There is also nothing to suggest that the aircraft did not continue on its Litchi mission after downlink loss.
Agreed. But, had the drone *not* crashed, we would see a *gradual* loss of uplink signal to mach the gradual loss of downlink signal. We didn't see that. Uplink signal ends abruptly, indicating a catastrophic event.
If it did continue then it most likely ran into obstacles around WP2, since its programmed ground clearance was only 24 m at that point.
This is what makes zero sense to me. We have an inconsistency in data. According to the log file, the vehicle ascended to 158' directly, and then moved on to the next waypoint, constantly ascending as it moved horizontally. But according to the waypoint *graph*, the vehicle STARTS @ 64 meters and DESCENDS to 24 meters. I don't know where that waypoint graph came from or what it's basing its altitude curve on, but it completely conflicts with the log file data. I would dismiss it.
In summary, your safe bets and firm conclusions all appear to me to be based on assumptions that are entirely unsupported by the data...
I disagree. A gradual loss of downlink signal is natural. An uplink signal loss would follow the same curve. Instead, we see an abrupt halt in the log file while we still have uplink signal. This says "catastrophic event" to me.
, so possible, but not indicated as likely at all.
I disagree. Based on the available data, I think a loss of power is very likely. But you have to dismiss the waypoint altitude graph, which doesn't jibe at all with the log files.
Thoughts?