I have all the updates, apps, ect... My mavic will only reach 17 mph in normal mode.  In sport mode the speed is there, 39.5 mph in calm air.
I know that my speeds have been:
27 mph normally , 22mph on a RTH and 39/40mph in sport mode.
I have reset all my settings with the same result.
Any ideas?

hi mate. When did it start happening? It must`ve been after one of the updates?

Siwyleeds mavic Posted at 2017-12-20 04:43
hi mate. When did it start happening? It must`ve been after one of the updates?

You got it.

Your front vision sensor may need to be recalibrated. This could be done through dji assistant 2.

Woe Posted at 2017-12-20 04:50
Your front vision sensor may need to be recalibrated. This could be done through dji assistant 2.

Thanks for the reply. Something I have not thought of...
That I will try and report back.

DroneDriver Posted at 2017-12-20 04:57
Thanks for the reply. Something I have not thought of...
That I will try and report back.

Does the speed slow down with the OA switched off? If so, recalibrating the OA may not be the answer. These speed reductions can be caused by the props being unbalanced, flying in lower air temperatures whilst the drone is cold and, most commonly, in higher wind speeds. Remember that the wind is much faster 400' above you than at ground level and wind direction can change in a split second.

A CW Posted at 2017-12-20 05:36
Does the speed slow down with the OA switched off? If so, recalibrating the OA may not be the answer. These speed reductions can be caused by the props being unbalanced, flying in lower air temperatures whilst the drone is cold and, most commonly, in higher wind speeds. Remember that the wind is much faster 400' above you than at ground level and wind direction can change in a split second.

I did not think of the sensor to restrict any speeds, normally. I will try the setting off to gather more info.
The props are new 8331s that I have not had any issues with. My last flight was at 65 degrees in zero wind.
I will remove the 8331s and start over, though. Damn good point.

No  matter what in sport mode, it ROCKS. The sensor effect seems to be logical, since they will normally be off in sport mode.

Thanks , bigtime for any and all suggestions. Seems to take collective knowledge and understanding to fly the DJI birds, these days.

DroneDriver Posted at 2017-12-20 05:50
I did not think of the sensor to restrict any speeds, normally. I will try the setting off to gather more info.
The props are new 8331s that I have not had any issues with. My last flight was at 65 degrees in zero wind.
I will remove the 8331s and start over, though. Damn good point.

No problem hopefully this will help. We are all here for knowledge . Fly safe.

Roll back to the previous version for the AC....

Woe Posted at 2017-12-20 04:50
Your front vision sensor may need to be recalibrated. This could be done through dji assistant 2.

You nailed it!
OA and 27 mph normal flight speeds have returned.

I did not change back to original props, although I planned to, did the alignment and POW.
Interesting, the optical sensors were working very well as a proximity sensor. Kept me off walls. I did notice the distances reported to obstacles were off, slightly. Should have been my clue.
The Mavic  accelerated slowly to attain full speed, another clue. Duh.

Thanks, again for your help.

What I learned, today:
OPTICAL SENSOR MISALIGNMENT CAN AFFECT SPEEDS during normal mode flying.

DroneDriver Posted at 2017-12-20 11:45
You nailed it!
OA and 27 mph normal flight speeds have returned.

KUDOS to  Woe

DroneDriver Posted at 2017-12-20 11:47
KUDOS to  Woe

Thanks. We are all here to help. Have fun and fly safe.

DroneDriver Posted at 2017-12-20 11:45
You nailed it!
OA and 27 mph normal flight speeds have returned.

Glad to hear that, hope you can enjoy the drone, should you have any further question, please feel free to let us know, lots of members here are willing to help, happy flying!