Advice on tricky homepoint situation, please

[Fleek]

What is best way to handle situation when your take-off point is down in canyon with insufficient GPS for locking in a home point. With altitude, the Mavic acquires satellite contact. Where is your homepoint going to be located? If homepoint is set to controller, controller is also at canyon bottom shielded from GPS fix.

Will homepoint be the most recent previous homepoint?

 

[msinger]

Will homepoint be the most recent previous homepoint?

No.

The home point will not be set until the Mavic acquires a good GPS signal. The Mavic will auto land at its current location if RTH is initiated before that point.

 

[ThisIsCusel]

Set RTH to hover, raise straight up until you get sat lock. Switch RTH to return to home. Fly.

 

[Pp09nlk2n]

You could also use Litchi and manually select a homepoint on the map with your finger.

What u don't want to do is set a homepoint anywhere in the canyon- even after you gain altitude. Because if Mavic ever needs to RTH, it will get part way home, Lose signal, then you are in trouble.

So better to tell it to hover on lost connection, or use litchi to select a home point on the map outside of the canyon so you can at least find it later if something goes wrong.

 

[geigy]

Nope, nope, don't do it - dangerous situation for several reasons. The rule is never launch the Mavic without an excellent GPS lock.

Why? Let's suppose you do. The home point that would be set after takeoff, may be based on an unstable GPS signal reflected from the canyon walls. You can't verify the location using your map home point, because your phone/tablet GPS is no more accurate than the Mavic's. If you have satellite maps, you may be able to visually verify that your home location is correct, or set it accurately in Litchi, but more than likely you don't have a good GPS lock and/or satellite map display on your phone or tablet either.

So you're stuck. If you can't get a good GPS lock on takeoff, then you should probably disable RTH because you don't know for sure that the home point is accurate - it could be a kilometer away. If the Mavic reaches sufficient altitude that you have a good GPS lock, and the Mavic is over a nice large landing area, then at that point you could safely set the home point to the current drone location.

In addition to compromised RTH functionality, which is bad enough, taking off with an unstable GPS lock risks a fly-away each time the GPS lock changes, potentially altering the Mavic's apparent position. Each time this happens, the drone will go flying off to get "back" to it's previous lat/lon location, and there is really no limit to how far away this can be.

But flying down a narrow canyon is not a good move, even if you start with a good GPS lock and a good RTH position. If you fly down the canyon, you risk losing GPS and going into ATTI mode! Nasty enough, but you are also at increased risk of losing rc signal and/or video. If, on the other hand, you fly up and over the edge of the canyon you risk losing your remote connection, and you are now completely dependent on RTH, which may be very inaccurate.