Stuck at ACCEL HEIGHT?

[Jeff Nielsen]

Trying a RNAV SID at KPHX after departure for some reason I can't get through the flap speeds.  The aircraft levels off around 5000' and won't accelerate or climb.  I have no clue why this happens.

Anyone else have this problem?

Thanks.

[Olympic260]

SID speed altitude restrictions maybe?

[Budbud]

Hi,

Difficult to answer since there is a lack of useful info.

_ How does the MCP look like (speed shown/hidden, altitude set, modes selected...)?

_ What annunciations are displayed on the FMA (thrust, pitch and roll modes active/armed)?

_ What thrust is selected (derates, %N1...)?

_ What is your TOW, and OAT?

_ What is the aircraft attitude when levelled off (nose up/down)?

_ Do you use fsuipc?

 

They are several reasons for the aircraft not accelerating/climbing, some normal (speed/altitude constraints on the SID), some others symptomatic of an issue with the sim or with a third-party addon.

> If the aircraft levels off with a nose down attitude and you have fsuipc, it is usually an issue with the profile in fsuipc and in this case the fix is to delete the profile and build a new one from scratch.

> If the aircraft cannot climb with VNAV SPD active and a low %N1, can be a wrong OAT.

> If the aircraft cannot climb with VNAV SPD active and normal climb thrust, it can be an excessive TOW.

> If the aircraft levels off with SPD | LNAV | VNAV PTH/VNAV ALT (don't remember exactly), then it is a constraint on the SID

> ...

Many different possible scenarii here.

If you provide more info, we will be able to rule out the irrelevant ones.

 

[Jeff Nielsen]

3 hours ago, Budbud said:

Hi,

Difficult to answer since there is a lack of useful info.

_ How does the MCP look like (speed shown/hidden, altitude set, modes selected...)?

During the takeoff roll everything on the MCP went blank.  LNAV/VNAV/N1 disconnected.

_ What annunciations are displayed on the FMA (thrust, pitch and roll modes active/armed)?

FMA annunciations seemed correct

_ What thrust is selected (derates, %N1...)?

Derate 2

_ What is your TOW, and OAT?

_ What is the aircraft attitude when leveled off (nose up/down)?

Level

 

_ Do you use fsuipc?

Yes, pay version

 

They are several reasons for the aircraft not accelerating/climbing, some normal (speed/altitude constraints on the SID), some others symptomatic of an issue with the sim or with a third-party addon.

> If the aircraft levels off with a nose down attitude and you have fsuipc, it is usually an issue with the profile in fsuipc and in this case the fix is to delete the profile and build a new one from scratch.

Didn't save a specific profile in FSUIPC, but did set everything up.  Maybe it creates one?

> If the aircraft cannot climb with VNAV SPD active and a low %N1, can be a wrong OAT.

Very possible

> If the aircraft cannot climb with VNAV SPD active and normal climb thrust, it can be an excessive TOW.

> If the aircraft levels off with SPD | LNAV | VNAV PTH/VNAV ALT (don't remember exactly), then it is a constraint on the SID

No hard or soft altitudes (oddly enough)

> ...

Many different possible scenarii here.

If you provide more info, we will be able to rule out the irrelevant ones.

I tried 3 flights.  The first flight I believe I was out of trim (forgot to set it), so the autopilot may have rejected it due top that reason.  I also did some other stupid things .  The second and third flights, I thought it should have worked, but....I think I might have forgot to re-load active sky after exiting the sim, so when I inputted the values again, the sim may have reverted back to standards when I was still using a historical WX value.

I'm using Active Sky, PPFX, FSUIPC, PFPFX/TOPCAT.  All the weights looked very close to what PMDG though it should be in the FMC.

I saw a post somewhere where the FSUIPC pay version may conflict with PMDG and I did read where PMDG does not recommend using it.  Of course I did it anyways.  I couldn't resist setting up all those buttons on my new X56 along with the tiller function.

I checked the SID over and over again and didn't see anything weird.  Not even a noise abatement procedure.  I'll try and set one up myself using 3000' and see if that works.

Here's my numbers out of the OFP I used.  I probably should have just run a generic no WX scenario and what not first, before diving right in with everything going.

AAL545 KPHX-KEGE (30 Dec 2017) #1
1
PFPX - Professional Flight Planner X. Non-commercial use only. www.flightsimsoft.com
Fuel Planning (lb) US Domestic Fuel Time
TRIP 6,873 01:12
HOLD KEGE 2,325 00:30
ALTN KRIL 1,853 00:21
FAR RSV 3,701 00:45
MIN T/O 14,752 02:48
TAXI 260 00:10
RELEASE KPHX 15,012 02:58
ARR FUEL KEGE 7,749 01:31
Load Planning (lb) N838NN Plan Limit
Empty Weight 94,779
Payload 150 Pax 29,850
Zero Fuel Weight Limit 124,629 136,001
Fuel 15,012 45,900
Ramp Weight 139,641 174,386
Take-Off Weight KPHX 139,381 156,971
Landing Weight KEGE 132,508 146,320
Underload 11,372 Lim ZFW
Max Extra Fuel 13,812 Lim LDW

AMERICAN AIRLINES FLIGHTPLAN - IFR AAL545 N838NN KPHX-KEGE
--------------------------------------------------------------------------------
ALL WEIGHTS IN POUNDS (LB) STD 30DEC/2200Z
--------------------------------------------------------------------------------
OFP 1 - PREPARED 30DEC/2139Z BY JEFF NIELSEN
AA545/AAL545 N838NN/B737-8ERW CF ROUTE: KPHXKEGE-MAN
DEP: KPHX/PHX 07L ELEV 1135 FT COST INDEX: 35 TTL G/C DIST: 448 NM
ARR: KEGE/EGE 25 ELEV 6547 FT INIT ALT: FL390 TTL F/P DIST: 480 NM
FUEL BIAS: 103.0% TTL AIR DIST: 466 NM
AVG WIND CMP: TL012 KT
ALT: KRIL/RIL 26 ELEV 5537 FT 95 NM
--------------------------------------------------------------------------------
CONFIG DOW PAX CARGO TOTAL ULOAD LIM ZFW TOW LDW
STANDARD 94779 150 0 29850 11372 ZFW MAX 136001 156971 146320
PLN 124629 139381 132508
ACT ...... ...... ......
--------------------------------------------------------------------------------
** TAKE-OFF DATA KPHX 07L **
COND: 139381 LB // RWY DRY // +22°C Q1017 CALM // LMT: CLIMB
CONFIG: FLAPS 1 // D-TO2 +40C // A/I OFF // A/C ON
SPEEDS: V1=145 VR=146 V2=149
ENG OUT: NONE
--------------------------------------------------------------------------------
** LANDING DATA KEGE 25 **
COND: 132508 LB // RWY DRY // +12°C Q1016 280/16 // LMT: STRUCT
CONFIG: FLAPS 40 // A/I OFF // A/C ON
SPEEDS: VREF=135 VAPP=147
ENG OUT: NONE
--------------------------------------------------------------------------------
FUEL CORR ENDUR
TRIP 6873 ........ 01:12
ALTN KRIL 1853 ........ 00:21
FAR RSV 3701 ........ 00:45
HOLD 2325 ........ 00:30
MIN T/O 14752 ........ 02:48 .....................................
EXTRA ...... ........ ..... CAPTAINS SIGNATURE (....)
TAXI 260 ........ 00:10
RELEASE 15012 ........ 02:58 I ACCEPT THIS OFP AND I AM FAMILIAR
ARR FUEL 7749 ........ 01:31 WITH THE PLANNED ROUTE AND AERODROMES
FUEL TANK CAP 45900 LB / MAX EXTRA FUEL 13812 LB LIM BY LDW
TRIP CORR FOR 2000 LB TOW INCR: +80 LB / 2000 LB TOW DECR: -67 LB
2000 FT LOWER: +33 LB / EET 01:12 CLB: 250/280/78 DES: 78/280/250
--------------------------------------------------------------------------------
KPHX STD 22:00Z/15:00L ETD 22:00Z ACT OFBL .... EST T/O 22:10Z ACT T/O ....

KEGE STA 23:40Z/16:40L ETA 23:27Z ACT ONBL .... EST LDG 23:22Z ACT LDG ....
SKD 01:40 PLN 01:27 TTL BLCK .... EST FLT 01:12 TTL FLT ....
--------------------------------------------------------------------------------
ATC ROUTE: N0445F390 YOTES5 YOOPR DCT DBL DCT FIDLE DCT
ALTERNATE PLANNING
--------------------------------------------------------------------------------
ALTN/RWY DIST ALT/FL MSA COMP TIME FUEL DIFF ROUTE
KRIL/26 95 FL220 168 HD017 00:21 1853 - COTND2 JESIE
MOST CRITICAL MORA 16800 FT AT DBL
--------------------------------------------------------------------------------

Thanks for jumping in to help.  These were the first flights I've done in the sim since we stopped developing for FS near the end of the beta for FSX. That was many...many years ago. This aircraft is nothing short of amazing.  I got well over a 1000 hours of enjoyment from their FS9 version.  This version is just off the charts.  I can't even describe it...LOL.

 

 

 

3 hours ago, Budbud said:

 

 

[Budbud]

11 minutes ago, Jeff Nielsen said:

I saw a post somewhere where the FSUIPC pay version may conflict with PMDG and I did read where PMDG does not recommend using it.  Of course I did it anyways.  I couldn't resist setting up all those buttons on my new X56 along with the tiller function.

I have always used fsuipc in both FSX and P3Dv4.1 with the NGX without any issue but some users have issues with the profile where for some reasons the flaps are retracted but fsuipc interferes and the aircraft flies like if the flaps were extended, hence a nose down attitude and unability to climb properly.

Otherwise, I don't see anything wrong on your OFP but still cannot really figure out what happens when you say that the aircraft refuses to climb or accelerate.

Do you mean that the aircraft attempts to reach the speed and alitude targets but cannot, or that it doesn't event trigger/start the acceleration/climb?

There is only two reasons I can see for the aircraft levelling off specifically at 5000ft:

_ Either you have 5000 entered in altitude window of the MCP

_ or there is a "at or below 5000ft" or "at 5000ft" altitude restriction further on the leg page.

Or it could be that the aircraft is in VNAV SPD mode and the FMC commands a level off because the aircraft cannot gain speed and reach the target speed (in this case, it can be any altitude, not specifically 5000ft).

In this case, it means that the ratio thrust/drag is not sufficient. Since the weights indicated in the OFP are not excessive and verified in the aircraft, it remains:

_ Thrust possibly too low (thrust is calculated mainly based on OAT) > check the weather injected in the sim for excessive OAT

_ and/or flaps/gear/speedbrakes extended > if the external model shows they are retracted, delete your fsuipc profile and rebuild a new one from scratch.

[Jeff Nielsen]

35 minutes ago, Budbud said:

I have always used fsuipc in both FSX and P3Dv4.1 with the NGX without any issue but some users have issues with the profile where for some reasons the flaps are retracted but fsuipc interferes and the aircraft flies like if the flaps were extended, hence a nose down attitude and unability to climb properly.

Otherwise, I don't see anything wrong on your OFP but still cannot really figure out what happens when you say that the aircraft refuses to climb or accelerate.

Do you mean that the aircraft attempts to reach the speed and altitude targets but cannot, or that it doesn't event trigger/start the acceleration/climb?

It doesn't even trigger the acceleration climb as far as I can tell.  I noticed during the takeoff roll it disengaged LNAV/VNAV-N1 and I had to try and re-engage it after T/O.

There is only two reasons I can see for the aircraft levelling off specifically at 5000ft:

_ Either you have 5000 entered in altitude window of the MCP

Yes, entered 5000 on the first flight then 8000 on the second flight.

_ or there is a "at or below 5000ft" or "at 5000ft" altitude restriction further on the leg page.

No restrictions.  VNAV was calculating all the way to 14000 I believe.

Or it could be that the aircraft is in VNAV SPD mode and the FMC commands a level off because the aircraft cannot gain speed and reach the target speed (in this case, it can be any altitude, not specifically 5000ft).

In this case, it means that the ratio thrust/drag is not sufficient. Since the weights indicated in the OFP are not excessive and verified in the aircraft, it remains:

_ Thrust possibly too low (thrust is calculated mainly based on OAT) > check the weather injected in the sim for excessive OAT

OAT was like 75F.  Cold by PHX standards.  

_ and/or flaps/gear/speedbrakes extended > if the external model shows they are retracted, delete your fsuipc profile and rebuild a new one from scratch.

I'm starting to think maybe this is the issue.  I'll check FSUIPC.  I assume when you say profile, you mean deleting the key assignments, etc..  I didn't save a specific profile.  

I'll try all this again tonight maybe after I get home form work.  I just got all my real world flights released for tomm., but dealing with FZRA in TX and delayed flights at the moment.  The joys of private fractional aviation at it's finest.  Now to figure out what's for lunch before the next AOG....LOL.

 

[Budbud]

18 minutes ago, Jeff Nielsen said:

I'm starting to think maybe this is the issue.  I'll check FSUIPC.  I assume when you say profile, you mean deleting the key assignments, etc..  I didn't save a specific profile.

If you don't a profile saved on separate file, the recommended is to delete the fsuipc.ini. It will rebuild when you launch a flight. Then do again your profile for the NGX.

I would however advise you to save the profiles of your different aircrafts in separate files, it saves the hassle of deleting the fsuipc.ini and doing all the other profiles again if you have several aircrafts. In this case you can delete only the incriminated profile and leave the other untouched.
You can check in the fsuipc documentation how to do that. It is quite simple since it is a simple 0 to change to 1 (or the other way round) in one of the line of the fsuipc.ini but I don't remember which one and I'm away from my sim computer.

 

18 minutes ago, Jeff Nielsen said:

I noticed during the takeoff roll it disengaged LNAV/VNAV-N1 and I had to try and re-engage it after T/O.

It is worth investigating further on this one because it should not happen. If you arm LNAV and VNAV on the ground before the takeoff, they should appear as armed in white below the TOGA|TOGA on the FMA.
The modes should activate automatically passing 400ft AAL (turning green and replacing the toga annunciation).

[Jeff Nielsen]

9 minutes ago, Budbud said:

If you don't a profile saved on separate file, the recommended is to delete the fsuipc.ini. It will rebuild when you launch a flight. Then do again your profile for the NGX.

I'm assuming this will mean I have to re-assign all 2000 keys and buttons?  :-( 

I would however advise you to save the profiles of your different aircrafts in separate files, it saves the hassle of deleting the fsuipc.ini and doing all your profile again.

Thankfully I only have the 737NGX, so when I do that, I won't have 30 other aircraft to redo

You can check in the fsuipc documentation how to do that. It is quite simple since it is a simple 0 to change to 1 (or the other way round) in one of the line of the fsuipc.ini but I don't remember which one and I'm away from my sim computer.

 

It is worth investigating further on this one because it should not happen. If you arm LNAV and VNAV on the ground before the takeoff, they should appear as armed in white below the TOGA|TOGA on the FMA.
The modes should activate automatically passing 400ft AAL (turning green and replacing the toga annunciation).

Well, if rebuilding the FSUIPC works, then I hope is this issue would be fixed.  Thanks for all your time.  I'll report back.

 

[Budbud]

4 minutes ago, Jeff Nielsen said:

I'm assuming this will mean I have to re-assign all 2000 keys and buttons?  :-( 

You can try to delete first only the NGX relevant lines in the fsuipc.ini if you are confident with the way the file is structured but it may be risky and may lead to further issues if anything else is deleted or if you forget to remove some lines.

Also, I'm still not sure that your issue is related to fsuipc. There is another potential cause for weird behaviour of the NGX is the panel state used to launch the flight being corrupted.
I didn't think of it with the initial symptoms described but the issue with the FMC modes disengaging, unless coming from a mistake in the FMC preflight or a failure triggered raises that possibility.

 

[Jeff Nielsen]

48 minutes ago, Budbud said:

You can try to delete first only the NGX relevant lines in the fsuipc.ini if you are confident with the way the file is structured but it may be risky and may lead to further issues if anything else is deleted or if you forget to remove some lines.

Also, I'm still not sure that your issue is related to fsuipc. There is another potential cause for weird behaviour of the NGX is the panel state used to launch the flight being corrupted.

I forgot to mention I also have chase plane loaded.  The initial start flight is the default which I loaded over with a default a/c.  I did notice that the PMDG loads first with the 2d panel.  Other than that I have the 737 start 'cold and dark'  Everything seems to work great.

I didn't think of it with the initial symptoms described but the issue with the FMC modes disengaging, unless coming from a mistake in the FMC preflight or a failure triggered raises that possibility.

It's still possible there's something I'm missing with the FMC preflight.  I double checked to make sure that even the ACCEL/THRUST REDUCTION heights were changed from soft to hard and that didn't work.

I'll try it again tonight hopefully and change/delete the FSUIPC relevant lines/files and see how that goes.

 

 

[Budbud]

Let me know how it goes. Try to note as much info as you can during your test flight so that if the issue occurs again it will easier to troubleshoot.

Amongst other infos:

_ FMA annunciations: modes armed and active and any changes in the modes annunciated

_ MCP configuration (altitude and speed preselected and modes armed) and actions before takeoff and during the initial climb

_ Aircraft configuration and steps during the initial climb (confirmed everything retracted after acceleration altitude)

_ TOW

_ Info regarding the CDU preflight:

> init ref page (ZFW, CI, initial cruise altitude)

> runway and departure selected and executed

> leg page checked (any discontinuity?, speed and altitude constraints)

> TO and climb thrusts selected

> Takeoff ref page: reduction and acceleration altitudes

_ If the aircraft levels off again

> matching altitude set on the MCP? 

> speed matching with either the selected speed on the MCP or with the target speed commanded by the FMC?

> Attitude of the aircraft: nose up/down?

> Everything retracted (confirmed on both cockpit commands and displays and exterior model)

...

[downscc]

You don't have to delete the fsuipc.ini, all you have to do is move it to your desktop. Run the test, there will be a new fsuipc.ini created but it is the default and yours is still on the desktop.

[Jeff Nielsen]

22 minutes ago, downscc said:

You don't have to delete the fsuipc.ini, all you have to do is move it to your desktop. Run the test, there will be a new fsuipc.ini created but it is the default and yours is still on the desktop.

Thanks Dan!

 

[Jeff Nielsen]

It looks like I got it all working now.  I ended up having to delete the FSUIPC.ini file and let it re-build.  Currently doing PHX-SFO now.  A little practice and I'll have it all down again just like the old days.  She's running like a champ now!!

Thanks for all the help guys!