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AP: very slow to capture ALT, loses selected ALT during turns, bad intercept angles on ILS, does not maintain ILS track, gets too low on GS, etc


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the title says it all basically, i noticed the following AP issues during some quick traffic patterns with ILS backup:

 

- the altitude capturing slows the VS to a crawl when nearing the selected altitude, it will go down to 100fpm at the end -> the ALTS CAP will flash for a very long time, and it will take several minutes to go from 2500 to 3000 when 3000ft is selected, for example

 

- when ALT mode, the altitude will sometimes wander around, the AP will often allow +/- 100 fpm which will make the aircraft gradually lose the selected altitude, see screenshot

1261491966_Screenshot2021-03-17085749.thumb.jpg.2af9f8baa00550781d7c951eeb921daf.jpg

 

unfortunately the windows snipping tools lost the screens but i also noticed:

- AP didnt manage to intercept ILS when at 30 degree intercept angle, pretty bad overshoot (no tailwand, doing like 180kt so no problems there)

- when on HDG/ALT mode and turning to intercept the final, up to -600fpm during turns (!) and didnt try to recapture lost altitude when straight and level again

- after overshoot of ILS track, very tame correction angle, i.e. took very long to get back on track

- LOC/GS mode allowed the plane to get 1 dot low on the GS, no "glideslope!" callout either

 

this is very disappointing to say the least 

 

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Hello, I saw some similar issues:

 - I also noticed slow VS when on speed mode, for example yesterday I was climbing to FL240 at around FL140 with speed selector at 200. And the VS was around 1.2. But I decided to use 250 as selected speed the climb rate improved a lot. 

- So far I never was able to intercept the GS, but I blame myself, and tbh since last patch the ILS on a lot of planes have been a hit and miss.

 

- The other issue that I had on boths flights was that after the las waypoint of the STAR the AP ignore everything, just continue like I’m heading mode. On The Dude video que uses HDG mode to intercept the APPROACH, so this may be totally my fault. But I do not have discontinuation or vectors selected on the FMS so I was expecting the AP to actually continue to the APPROACH waypoints (The legs pages and the mdf actually shows the correct next waypoint as active)

 

Sorry if my explanation is a bit of a mess, English is my secondary language, feel free to ask me anything.

 

 

thanks!

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  • CRJ Forum Moderator
1 hour ago, santii90 said:

- I also noticed slow VS when on speed mode, for example yesterday I was climbing to FL240 at around FL140 with speed selector at 200. And the VS was around 1.2. But I decided to use 250 as selected speed the climb rate improved a lot.


200 knots is too slow for a SPD mode climb to FL240. In this mode, the aircraft uses pitch to control airspeed with a fixed amount of engine thrust. The nose would have to pitch up very high to keep the speed at 200 knots, which makes aerodynamic drag increase dramatically.
 

The CRJ wing is designed to be most efficient at indicated airspeeds between 240 and 300 knots. It would be best to climb at a selected speed if at least 240-250 knots. Once above 10,000 feet, many operators increase the selected speed to 290 knots. 

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some further observations

- just now trying the DODEN9T out of EDDL/23L, the plane blew right past the first waypoint (a left turn), turned way late, while on SPD/NAV/AP engaged

- wanted to switch to PITCH hold as suggested by a RL CRJ pilot on these forums, hit VS once to get VS +2.7, hit VS again for PTCH and set the PITCH to around 7.5 while in the belated left turn -> plane started descending (!) at 1400fpm, didnt follow the vertical FD bars at all, at which point i ragequit 

 

sorry to say but this is in no way enjoyable. i really wanted to like the CRJ and i'm sure aerosoft did what they could but MSFS is just an atrocious sim at this point

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40 minutes ago, JRBarrett said:


200 knots is too slow for a SPD mode climb to FL240. In this mode, the aircraft uses pitch to control airspeed with a fixed amount of engine thrust. The nose would have to pitch up very high to keep the speed at 200 knots, which makes aerodynamic drag increase dramatically.
 

The CRJ wing is designed to be most efficient at indicated airspeeds between 240 and 300 knots. It would be best to climb at a selected speed if at least 240-250 knots. Once above 10,000 feet, many operators increase the selected speed to 290 knots. 

I was almost sure that was an error on my side. Thanks for the answer and sorry!

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Because we believe this topic has been answered we have closed it. If you have any more questions feel free to open a new topic.

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