Flight log data

I am new-ish to ardupilot and am having a hard time understanding what all the parameters in the flight logs in mission planner are. I am looking for x,y,and z axis velocites and rotation rates. I am using a pixhawk 2.4.8 with an Radiolink SE100 GPS module. Other useful things I would like to know are the sampling rates for the sensors as well as the timestep for the logged data. Any help or explanation anyone could offer would be much appreciated. I’ll add a link to one of my flight logs for reference.


Rotation rates are in the gyro record: Onboard Message Log Messages — Plane documentation
The GPS record has speed info.
Rates vary, but each record is timestamped.

Thanks. I noticed two parameters Spd and VZ. Is Spd the airspeed in the body fixed frame of the aircraft? Is VZ the rate of change of the altitude of the aircraft in the in the body fixed frame? Or, do I need to get those velocity values using the angle of attack (alpha) and sideslip angle (beta)? I am not using an airspeed sensor.

Depends what SPD you’re looking at.

GPS.Spd is the GPS speed (ground speed)
TECS.SP - Estimated true airspeed. Based on synthetic airspeed if you don’t have a pitot tube.
ARSP.Spd is the airspeed if you have a pitot.

GPS.VZ is the GPS based vertical speed. There’s also XKF1.VD, that’s the EKF filters outputted vertical speed. These are both measured as earth referenced, down being positive. Negative is a climb. Positive is a descent.

Thanks, that really helps! Is there any parameter that estimates the body-fixed velocity in the y direction? If not are the estimates for AoA (alpha) and sideslip (beta) reliable such that I could use them to calculate vy?

Have a look at the link above in all the XKF, NTUN, CTUN, and TECS values. It’s likely whatever calculation you want is already there.

Great. I think you are right. I’ll keep looking into those. Thanks for your help.

1 Like