Better understanding of setting: nav_rth_climb_ignore_emerg

[Sibre3]

Can someone clarify the operation of nav_rth_climb_ignore_emerg.
The setting docs says : If set to ON, aircraft will execute initial climb regardless of position sensor (GPS) status.
However it makes no mention if this means hwHealthStatus, non trusted position or poor sensor accuracy?

It would also be useful to know how it interacts with nav_position_timeout after RTH occurs? For example; will it start to climb and then land once the nav_position_timeout expires. Or will it first wait until nav_rth_altitude is made and then emergency land?

[sensei-hacker]

"regardless" can be taken literally - regardless.
Untrusted position, no fix, or we haven't even heard anything from the GPS for a while - it may have fallen off of the aircraft entirely.

[sensei-hacker]

nav_position_timeout begins when there is no longer valid position data. When that time expires AND it's doing a failsafe RTH, it will initiate the emergency landing procedure. This will occur regardless of what stage of RTH it is in - including climb.

[Sibre3]

Thanks for the prompt reply. I figured as much. But a second opinion from someone in the know is always beneficial.
It would then seem best to increase nav_position_timeout = 10 if nav_rth_climb_ignore_emerg is going to be activated on a quadcopter.
That way it could make the most out of the climb, before an emergency landing. However, its a long way down using the failsafe LAND procedure based on a timer and throttle if the signal doesn't return.

If you're wondering why I asked. A few of us were discussing a dead-reckoning of a type for quadcopters.
So as to climb above a microwave link that a friend accidently flew to closed too. If he had the aforementioned settings in use, he may possibly have got his GPS and RX link back again.

[sensei-hacker]

That makes sense to me. To set the timeout to about how long it takes to make the climb. How long do you think it would take to make the climb?

Also, ten seconds or a little less seems a reasonable amount of time for dead reckoning with cheap MEMS sensors, if there is little vibration on the aircraft. Over the course of minutes dead reckoning becomes completely unusable because of double integration, but it can work for several seconds.