If my flight plan takes my drone out of wifi range, am I right that it will still execute the flight plan, even though this won't be visible on my phone screen, visiting each waypoint, assuming it has enough battery power and the GPS signal isn't lost?
Yes, and no. If it has adequate battery levels it will continue on its plan as instructed. If it thinks it hasn't enough power to complete the mission it will engage RTH and go straight back to the home position. If it is out of contact and hasn't got enough power to RTH it will go as far back towards home as it can and it will land.
I have done over a dozen flight plans that have involved loss of signal and this is how it goes:-
The screen goes black with hints of white noise, as it normally does when losing signal. Despite prior explicit notification in red across the bottom of the screen that it will return to home if signal lost it does NOT return to home. The map shows the last point the controller knows the drone to be at.
BUZZZ! The controller buzzes! There is another connection with the drone. It updates a new position. The screen goes black again. At this point I usually start speculating about taking up a different hobby. There may be another brief contact again, depending on the altitude and topography. I once got a brief update at what was the furthest extremity of the flight plan, which was nice, but the signal was lost again for several more minutes. The map will update to show a green drone icon marking the last known position of the drone, it stays in the same place and goes red when there is no live connection.
BUZZZZ! It's back! Well, it's alive! It hasn't crashed yet! It's nearly halfway home! Often it will regain signal at just the point you expect it to, at just the position you planned it would. Unfortunately, this often involves severe time dilation and distortion fields. You need to have a clear idea of what time you need to begin to panic. Never launch a flight plan without verifying just before you hit the play button exactly what the duration is. It will usually take longer. Although you can plan to fly it at 11 metres per second it will never manage to achieve that as a sustainable average. You might think three minutes have passed but only twenty seconds have in reality (in this it can be a bit like sex). I now make a point of calculating a "don't panic until" time before I launch the flight plan. Once I passed that time. It was a valid time to panic. There was a buzz! But by this time I knew the battery would be nearly dead. I was right, I managed to get back video from the drone and I could see I had just enough power to make a safe landing but not to complete the return to home. Fortunately, the drone was over a field not a private garden or road. I managed to land and retrieve the drone a few minutes later.
On another occasion, I had launched an ambitious flight plan and the signal had been lost as I anticipated it would be. A good two minutes before I was ready to begin panicking I heard the Anafi hovering above me. Always have the last point in your flight plan within earshot of the place you will be standing, ideally also right at the RTH location. I thought it was highly unlikely that it had completed the mission. It hadn't, I later discovered watching the video that it did a precautionary RTH on the basis of low battery level at the furthest point from home so only half the mission was complete. But at least it did return safely.
I suggest you never plan a mission in excess of 12 minutes and only attempt a flight over 8 minutes if you have already verified that wind levels are modest. The simplest way to check wind levels is to fly a square at maximum altitude, ten seconds flat out North, ten seconds flat out East, ten seconds South and ten seconds West. This should alert you to whether the maximum speeds you can attain are limited or vary significantly with direction flown. If there is a direction that you can't fly as fast in this will impact your flight and you should consider increasing your safety margins or putting off your plan to another day.
Or was that Zaphod Beeblebrox? It's much worse if both of your heads panic at the same time!
