still trying to understand Failsafe RTH

[engravosaurus]

Hi
Still newbie trying to understand Failsafe RTH

manual says

The Forward Vision System allows the aircraft to create a real-time map of its ight route as it ies. If the Home Point was successfully recorded and the compass is functioning normally, Failsafe RTH will be automatically activated if the remote controller signal is lost for more than three seconds. The aircraft will plan its return route and retrace its original flight route home. The aircraft will hover for 10 seconds at its current location. When it regains signal connection it will wait for pilot commands. The Return-to- Home process may be interrupted and the pilot given control of the aircraft if the remote controller signal connection is re-established.

So signal is lost and AC starts home, got it
Then if signal re-established pilot can interrupt RTH and take control, got it

but what do the two underlined sentences mean?
when does it hover 10s?
if when the signal is re-established it waits, then there is no need to interrupt...
so how do the two underlined sentences fit?

thank you

 

[smiller]

If signal is lost, during during smart RTH the aircraft will retrace its route for a limited time/distance in an attempt to regain communications, and at the limit it will pause for ten seconds. It would probably be clearer if the underlined section said 'If it regains signal connection it will wait for pilot commands' because if it does not it will then initiate a conventional (beeline) RTH back to its origin point at the preset RTH altitude. At any point if the signal is recovered the pilot may cancel RTH and resume controlled flight.

 

[engravosaurus]

During smart RTH the aircraft retraces its route for a limited time/distance in an attempt to regain signal, and at the limit it will pause for ten seconds. It would probably be clearer if the underlined section said 'If it regains signal connection it will wait for pilot commands' because if it does not it will then initiate a conventional (beeline) RTH back to its origin point. At any point if the signal is recovered the pilot may cancel RTH and resume controlled flight.

Thank you. Still struggling.
Am discussing Failsafe RTH, not Smart RTH. (manual discusses Failsafe, Smart and Low Battery RTH)
So...

RC signal lost and GPS intact and the AC starts Failsafe return, retracing its route.
What happens if the RC signal is never re-established?

If it regains an RC signal it will stop the Failsafe return, and hover 10 seconds awaiting directions. True?
What if it receives no directions? (what is "beeline" RTH? not covered in the manual)

 

[smiller]

I'm sorry, smart RTH in the first sentence was a typo, I meant failsafe RTH. Oops

RC signal lost and GPS intact and the AC starts Failsafe return, retracing its route.
What happens if the RC signal is never re-established?

If signal is never re-established during the failsafe RTH 'backtrack' period then the unit will begin a direct flight back to the origin (what I described as beeline [not an official DJI term], meaning it is not following any recorded course at this point but rather a direct line back.)

If it regains an RC signal it will stop the Failsafe return, and hover 10 seconds awaiting directions. True?
What if it receives no directions?

If the RC signal is re-acquired at any point during failsafe RTH then the aircraft will return to RC control. If you enter no commands with the controller then the aircraft will hover until you do, or until the low battery RTH activates at which time the aircraft will return to the home point and auto-land.

Note that many features of RTH (object avoidance, landing protection, etc.) can be enabled/disabled separately so be sure to have these on if you want them (you probably do.) Don't feel bad if it all isn't clear right away, the RTH options are complex and DJI does a rather poor job of explaining them in the manual.

 

[engravosaurus]

"If signal is never established during the failsafe RTH 'backtrack' period then the unit will perform a direct flight back to the origin..."

This will be accomplished at the Failsafe altitude specified? So above known obstacles?

Thank you.

 

[smiller]

"If signal is never established during the failsafe RTH 'backtrack' period then the unit will perform a direct flight back to the origin..."

This will be accomplished at the Failsafe altitude specified? So above known obstacles?

Yes, which is why it is important to set the RTH altitude correctly. Forward vision object avoidance may save you if you screw up but it's best not to count on it.

 

[engravosaurus]

Thank you.

One more please. If the AC can "beeline" home at the specified altitude, what is the purpose of Failsafe backtracking?

 

[smiller]

Thank you.

One more please. If the AC can "beeline" home at the specified altitude, what is the purpose of Failsafe backtracking?

The idea is that if signal has been lost it likely may be due to the aircraft flying behind an obstruction of some kind (hill, building, etc.) and it is more elegant to at least try a reasonable backtrack to see if you can regain signal rather than immediately resorting to the brute force method of climb and beeline back. It's a good idea I guess although I'm not certain how often it really comes into play in a meaningful way.

 

[engravosaurus]

Ok
I suppose if you were far out on a serious activity, and could backtrack some distance and recover, you could resume and perhaps complete the task. Whereas the Smart RTH is really an abort of the task.
Agreed
the authors of the manual seriously needed an English speaking editor. The narrative sections are really quite poorly written.
Again, thank you.

 

[smiller]

Yes, it's better than a lot of Chinglish but still there's a lot of room for improvement, especially for such a complex and costly device.