Altitude Logging

[SlabRyder]

With the Mavic Air and Dji4 App is there anywhere I can go back into my flights and see what the AGL Altitude achieved was?

 

[msinger]

No. The aircraft does not know how high it is above the ground.

When flying low to the ground, the downward sensors will show a reading in the flight logs. That's the only (estimated) value that measures the distance between the bottom of the aircraft and the ground (or closest obstacle) beneath it.

 

[sar104]

With the Mavic Air and Dji4 App is there anywhere I can go back into my flights and see what the AGL Altitude achieved was?

Not directly, but you can use the txt flight log to create a kml track of the flight, and then look at that in Google Earth or, if you want to be really fancy, combine it with a DEM to give a continuous record of AGL as a function of position and time.

 

[Bruce Lythe]

Ok so I get its it's a Digital Elevation Model. But where does a hobbyist access one at a sensible price?

 

[Keule]

Ok so I get its it's a Digital Elevation Model. But where does a hobbyist access one at a sensible price?

There are a few providers from where you can download DEM models for free.
If 30m resolution is good enough for you, try for example here: https://dwtkns.com/srtm30m/

 

[sar104]

Ok so I get its it's a Digital Elevation Model. But where does a hobbyist access one at a sensible price?

You don't need to buy anything - most of this capability is web-based. For example, using a site such as GPSVisualizer, you can take a kml flight track and convert it to get ground elevations, and then subtract those from the flight altitude AMSL (obtained from flight height above takeoff point plus takeoff point elevation AMSL) to get flight height AGL. This is post flight data processing of course - none of the existing control programs that I'm aware of do this during flight.

 

[Hummingbird.UAV]

With the Mavic Air and Dji4 App is there anywhere I can go back into my flights and see what the AGL Altitude achieved was?

Yes. Go to the flight record screen in the GO4 app, select a flight and either play it back or move the time slider. Watch the altitude readout at the top of the screen. Also in the Flight List it shows the max altitude (AGL) for each flight.

 

[sar104]

Yes. Go to the flight record screen in the GO4 app, select a flight and either play it back or move the time slider. Watch the altitude readout at the top of the screen. Also in the Flight List it shows the max altitude (AGL) for each flight.

That's not AGL, it's height above the takeoff point.

 

[Hummingbird.UAV]

That's not AGL, it's height above the takeoff point.

Oh, but my takeoff point is usually ground level.

 

[sar104]

Oh, but my takeoff point is usually ground level.

Right - so valid in the flatlands. Not true in hilly or mountainous terrain though.

 

[SlabRyder]

Yes. Go to the flight record screen in the GO4 app, select a flight and either play it back or move the time slider. Watch the altitude readout at the top of the screen. Also in the Flight List it shows the max altitude (AGL) for each flight.

Found it, thank you