Nav Drift in BER Mode

[bloodnok]

I noticed in a mission recently that whilst on the ground and the master mode set to BER, the nav system started to drift, contrary to the manual and previous patches. I believe the problem is something to do with the wind compensation. To test this I setup an aircraft on the runway and recorded the nav drift reported by the aircraft every 5 minutes at different wind speeds.

 

 

 

As expected no drift was reported when there was no wind however curiously the rate of drift was the same for any wind speed above zero.

 

 

 

To check that the aircraft was not falsely reporting a drift I setup another aircraft on the runway with a navigation point 2.5km away at a bearing of 242 from the aircraft. Recording the bearing and range to the waypoint every 5 minutes. Again as expected the waypoint remained fixed with no wind and at 10ms-1 the waypoint started to move quite significantly.

 

 

 

During missions I have also seen excessive nav drift in flight whilst over water. Flights of only 30km over water have resulted in nav drift of a few 100m. Once back over land the waypoint snaps back to the correct position due to the TERNAV update. This effect was not seen in missions with no wind.

 

 

Apologies for the long post but hopefully this should provide enough detail to solve the issue.

 

 

Many Thanks

[Machalot]

I found this thread during a search for something else, but it seems interesting.  For the over water drift, how precisely was your heading aligned on your ADI on takeoff?  That could easily give you lots of drift.  Over a 30 km straight line flight segment, a half degree of heading error would result in about 260 meters of crossrange nav drift.  I don't know if TERNAV corrects heading errors or only position errors.

 

I don't know what to say about the BER drift you measured, though.