investigating Altitude indication is affected by vertical speed [now with trackfile]

[Rongor]

This is best noticeable while using Bob (most stable way to fly straight and level currently) but also happens in absence of Bob.

When in level flight and starting a climb or descend, the indicated altitude instantly adds some tens to hundreds of feet. This offset then gets subtracted again when vertical speed is decreased back to zero.

Same for descends, the moment you return to level flight, some tens to hundreds of feet instantly get added to the altitude indication. 

It behaves like the current vertical speed is in a way added to the actual altitude indication, therefore showing higher altitude during climb and too low altitude while descending.  

Will add a trackfile tomorrow

Edited August 14, 2024 by Rongor

[Rongor]

In this track you seem me activate Bob. The moment I acknowledge cautions and switch the center MFD to the map, Bob is already in control.

Then I do a series of climbs and descents.

Whenever the vertical speed increases, the altimeter rapidly adds to the altitude. The moment the vertical speed is set, there is a noticeable pause in altitude increase indication, then it continues at a slower speed. When returning to level flight by reducing the vertical speed to zero, the altitude indication decreases for a bit, although there hasn't been any descent.

Same for the opposite. Introducing descent instantly decreases the altitude at a higher speed than it continues to decrease when the maximum negative vertical speed has been achieved. When reducing the descent, the altimeter actually increases for a bit.

It's very subtle at times but it should be easy to observe.
Its more noticable at higher air speeds. This track was made below 100 kts, maybe I should've gone faster.

vertical speed adds to alt.trk