KlooGee
First Officer
Flight distance : 16783757 ft
United States
Offline
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First off, I'm very sorry to hear of the loss of your aircraft. I know it can be rough on the emotions and wallet when that happens. Below is my attempt to review your logs to try to understand what may have happened. It is done so in an effort to help to see if I understand and interpret the logs correctly, but also to serve as a learning point for myself, others, and for the pilot for future flights. Having said that, below is my interpretation. Let me know if anybody sees something I'm interpreting incorrectly or missing.
After a quick look at the logs, it looks to me like this is a continuation of another flight on the same battery. Firstly, the first line of the log starts with a time stamp of "4m 49.4s" and the home point is 29.5ft away immediately as soon as the flight is started. So my assumption is that the pilot took off originally (log would be in a different log file), flew around a bit, and then landed about 29.5ft away from their original take off point.
Wrathpanda, can you confirm that and do you have any details about that flight that immediately preceded this one? Did it land normally from the first flight or was it a crash landing? On this flight did it land into the dirt, snow, bushes, or something like that?
At first glance at the Altitude results recorded in the log files, there are a couple of things that stand out. As mentioned above by others, the -275ft values are a bit abnormal, but could be explained by elevation changes in the landscape. I had a quick look via maps and Google Earth, but in the area of the flight, from a digital view via the internet, that doesn't seem likely. There are terrain changes in the area, but in the direct area of the flight, it doesn't seem like it would be almost 300ft difference. However hard to tell without being there.
Wrathpanda, any thoughts on elevation changes of the landscape?
Also, the other thing that is odd is that the VPS elevation sensors were registering a value of somewhere around 6-12ft for the entirety of the flight even with the altitude coming from the IMU (i.e. barometer) changing quite significantly. When I've seen this in the past, it had quite often been a 3rd party accessory (i.e. sunshade, legs, etc) attached to the aircraft. Other times it has been due to moisture or dirt on the VPS sensors.
Wrathpanda, is it possible that in the first landing that immediately preceded this flight that the sensors could have gotten something on them?
As MSINGER mentioned, when the RTH procedure was invoked (7min 56s mark), it rose to an altitude higher than the 20m (65ft) value set. However, my theory for why it did this is not due to wind catching it, but instead because the VPS sensor was registering a value of around 7 or 8ft high and it was using that instead of the altitude being registered by the IMU (i.e. barometer). So it was trying to continue up to a height of 20m. It would have continued to go higher and higher however the pilot cancelled the RTH procedure and it went back to GPS mode so it stopped climbing.
The interesting thing is that the aircraft was only about 18ft up and 95ft away with 34% battery left with the pilot in full control of the aircraft when the RTH procedure was invoked. As a potential learning point, unless there are extenuating circumstances that aren't apparent in the logs, I would suggest the pilot to manually fly the aircraft home in this situation rather than flipping to RTH and asking the computer to do it.
During the RTH procedure, as it was rotating to the correct heading and then trying to rise to the 20m RTH altitude, it appears the wind may have been pushing it a bit further away from home. My guess is that it was this extra distance and extra height that caused the pilot to choose to exit RTH mode and try to take control again.
Wrathpanda, any comments to add at this point about what you saw in real time?
Once the pilot took control again after the RTH procedure, it looks to me like the aircraft was responding to the pilot's stick inputs as expected. When the pilot gave stick inputs to move forward, it moved forward. When the stick inputs were to go backwards, it went backwards. When stick inputs said to climb, it climbed, etc, etc.
At this point the aircraft was approximately 118ft away at around the 9m 15s marker and with 17% battery left. From then, the pilot provided stick inputs that led the aircraft much further away from the home point with it eventually getting out to just over 900ft away at the 11m 1s marker with 3% battery left.
During this trip away from the home point, the battery got to a critical level (around 10%) at the 10m 13s of the flight. At that point, the aircraft went into AUTO LANDING mode and started to descend. Even though the battery was only at 10% and was auto landing, the pilot was still providing stick inputs for almost another 50 seconds that continued taking the aircraft further away.
At about the 11m marker with 3% battery left and being about 900ft away, the pilot's inputs changed to start bringing the aircraft back closer to the home point. The aircraft is still in auto landing mode and descending during this period.
For the last couple minutes of the flight, the pilot was giving the aircraft conflicting inputs at different times. For a bit, it was coming back closer to home, then the pilot would change the inputs and send it further away. This continue back and forth for bit until the last 20 seconds when there was very little input into the sticks. while the aircraft continued to descend. My guess is that it eventually ran out of battery and it was at that point the log ended. With the way the elevations were a bit jacked up, its a bit hard to know for sure how high exactly it was when the battery finally died. However, for the last several seconds, it looks like its location was quite steady. Its GPS coordinates aren't moving hardly at all and its speed is pretty much at 0.
I would think it should be quite near where the GPS coordinates mention.
Okay, so that is my interpretation. What have I missed or interpreted incorrectly?
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