I am experiencing IAS setting problem with AP:Before I connect the AP I set IAS 170 and Altitude 10000FT. After takeoff , manuayl climb. I click AP hopping plane will climb to 10,000ft with IAS 170 angle. My climb indicates over 4000Ft , IAS starts to fall and STAL warning I disconnect AP. In this scenario even I click ALT Setting plane keep climbing.Will you please advise, if I am doing wrong. I read manual several timesThanks

Please be aware that the IAS knob on the EFIS DC does NOT act as an input to the FD/AP, nor do any values present on the EADI screen. The aircraft will hold whatever speed it was doing when IAS hold was engaged on the FD mode selector (on the glareshield). This value can be adjusted using the pitch wheel on the autopilot controller (which is on the pedestal), you can check the selected value by using the tool tip. If you select IAS mode at 120 kts, the aircraft will attempt to maintain that speed when the AP is engaged - even if you are doing 170 kts by this point and have set the EADI speeds to 170 kts. In this situation, you should disable IAS mode then re-enable it, which will reset the target value to your present airspeed.The only other cause for the problem I can think of is engaging the autopilot when the aircraft is significantly out of trim. Otherwise you have some conflict with your controlling hardware or FS UIPC. Full functionality of autoflight is outlined in Chapter 8 of the AOM (p474 and p486). Hope this helps.廖傑英

Ahmet, you should either accelerate to 170 before engaging IAS pitch mode or what I do is set up a VS pitch mode for 1000fpm initial climb and as she accelerates to 170 switch to IAS.

Dan and Ckyliu,Thanks for your replay. I connect the AP when i reached to 170 and 1500Ft altitude, but already problem develops, runaway trim happens and EADI pitch mode shows over 4000Ft.Where shall I look at FS UIPC?Thanks

I connect the AP when i reached to 170 and 1500Ft altitude, but already problem develops, runaway trim happens

Please make sure you most definitely have not touched the IAS button until 170 KIAS. It's not when the AP is connected that is important, the target airspeed is set when the IAS button is pressed (it doesn't matter if AP is connected or not). Double-check the IAS target value by reading the tooltip of the AP pitch wheel on the pedestal. If you are absolutely certain you're operating the aircraft correctly, then you can consider that the problem is elsewhere. Are you using FS UIPC to map the controls? I don't use it myself but I've heard of other users experiencing problems with it in the past as regards the PMDG JS41, it may be worth searching the forums. Might be something to do with the new FS2Crew if you're using that - afraid I've not tried that yet so I cannot help you there either.

I saw this problem recently too, when testing FS2Crew. I don't know if it's actually related to FS2Crew or just a coincidence...I found that the trim would runaway and the airplane would would begin an uncontrolled climb anytime the autopilot were engaged while in IAS mode. Prior to engaging the AP, the airplane was in trim, and I was flying the FD command bars. I determined that the problem could be avoided if the AP is engaged while another vertical FD mode is active, such as VS. For instance, set the IAS to 170 and fly the FD; when you want to engage the AP, first press VS, engage the AP, then immediately reselect IAS. The AP should behave normally.As soon as the bug tracking software is updated, I'll put this one in the database.

I saw this problem recently too, when testing FS2Crew. I don't know if it's actually related to FS2Crew or just a coincidence...I found that the trim would runaway and the airplane would would begin an uncontrolled climb anytime the autopilot were engaged while in IAS mode. Prior to engaging the AP, the airplane was in trim, and I was flying the FD command bars. I determined that the problem could be avoided if the AP is engaged while another vertical FD mode is active, such as VS. For instance, set the IAS to 170 and fly the FD; when you want to engage the AP, first press VS, engage the AP, then immediately reselect IAS. The AP should behave normally.As soon as the bug tracking software is updated, I'll put this one in the database.

Nick,That is exactly what is happening to me. I tried to overcome runaway trim..It is not much fun flying like that. I will wait until bug tracking updated.Thanks

Hi if ur using fscrew2 whilst u having this problem try the solution found in the manual of the fscrew2 for the js4100Situation: I commanded the FO to make a heading/altitude/speed/course change, but the value

Hi if ur using fscrew2 whilst u having this problem try the solution found in the manual of the fscrew2 for the js4100Situation: I commanded the FO to make a heading/altitude/speed/course change, but the value

Yeah, the issue described in the FS2Crew documentation is not the same as the problem I noted. In this case, there is no change in the IAS values on the PFD. It is strictly an autopilot/trim issue which, as Bryan pointed out, FS2Crew is not manipulating.