david.p.mann
Captain
Flight distance : 18669501 ft
United States
Offline
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Several detailed comments that may help you:
First, the map screen has three views or layers - Standard, Satellite and Hybrid. When confirming your aircraft and RC positions, I recommend using only "Satellite" or "Hybrid" view as the map images displayed are based on satellite photos instead of the potentially-flawed and/or inaccurate map "drawings" shown in Standard map view.
Second, the P3's current aircraft position (red arrow) is updated continuously any time the P3 battery is powered on (even when the propellers are not running). However, the aircraft Home Point is only updated AFTER turning on the propellers.
Third, after powering on the P3 and calibrating the compass but BEFORE turning on the propellers, ALWAYS check your current indicated aircraft position (red arrow) and RC position (blue dot) on the map in satellite (or hybrid) view mode. Assuming you are holding the RC within a few feet of the P3, the aircraft position (red arrow) and RC position (blue dot) should be within a few feet of one another on the map AND you should confirm these indicated positions are, in fact, accurate.
The P3, P2 and Inspire quads all occasionally get a bad GPS fix on initial battery power-up, even after successful compass calibration and "Ready to Fly" are displayed (7+ satellites). This is more likely to happen on your first flight of the day in a new location. Even with 7+ satellites, I have seen inaccurate positions shown on the satellite view map. The worst I have personally seen has only been about 50 feet with both my Inspire and P2 (once or twice in 30+ flights on each).
BUT - even this "small" error of 50 feet could be a big problem. Let me explain. If you take off in GPS mode with a bad GPS fix and an inaccurate current aircraft position and the P3 then gets a good/accurate GPS fix in the air, the flight control software MAY interpret this as the aircraft getting suddenly moved out of position by a wind gust. It MAY then suddenly try to fly back to the original "incorrect" Home Point. I'm not talking about a Return to Home (RTH) event; I'm talking about the P3 taking off at full speed at current altitude in the direction of the incorrect original aircraft position/home point because it THINKS it just got blown out of position by the wind. I believe this is, in some cases, what people have reported as a fly-away event. If this situation occurred, your aircraft could suddenly fly full-speed into a nearby tree, building or people!
THE FIX: To avoid this, hopefully, rare possibility, check your indicated aircraft position (red arrow) on the map (in satellite view mode) before turning on the propellers. If you observe a bad initial GPS fix (incorrect aircraft position), pick up your P3 and walk around with it in a large circle so it can see more satellites or, at least, recalculate its position several times because its moving. Hopefully, you will then get a good GPS fix. If you are in an area where the aircraft's view of GPS/GLONASS satellites is hindered, you may have to move to another area with a clear view of the sky. Set the P3 down, check the satellite map, if the current aircraft position is now accurate, you are good to go.
Fourth, after powering on the aircraft propellers, the Home Point position will update. Now, BEFORE taking off, check the updated Home Point position (green circle with H) on the map in satellite (or hybrid) view mode, as instructed by the nice lady's voice on the DJI Pilot app. It should be the same as the current indicated aircraft position (red arrow) and should accurately reflect the aircraft's actual current position. If not, something is wrong. Don't take off until you figure out what is causing the aircraft's current position and/or home point to be incorrectly indicated.
Finally, based on a few other threads in this forum, before taking off you should also check that the aircraft's orientation (direction nose of P3 is facing) is correctly shown on the satellite map. Also, check that the P3's orientation relative to the RC is correctly shown on the compass graphic in the lower left-hand corner of the DJI Pilot app Camera screen. In some RARE reported cases, this orientation can get 180 degrees out of whack. A couple reports suggest this MAY lead to all flight controls getting reversed, which would result in a nearly impossible to control aircraft. This is pure speculation. But it certainly can't hurt to check the accuracy of the indicated aircraft orientation. If it's not correct, I'd suggest performing another compass calibration. |
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