Flight plan change en route/Throttle Cut on Approach

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21

I am a little confused here. Autopliot IS engaged at the time of the throttle failure or not?

Just out of curiosity, what are you using for a controller? Gamepad, joystick, yoke? Any other controls connected, switch panel, throttle, hotas?

As @mdapol asked, does this occur with any other aircraft or is it just on the Daher? Does it happen everytime? Are there any specific actions you take at the time of the failure? If I was to try to reproduce the failure, what steps would I need to take?

EDIT:
What is your experience level? Just asking to try to get a handle on the possible causes. New pilot error, unfamiliarity with controls? Someone with thousands of sim hours won’t be making the same mistakes as someone new to the hobby. Helps to know so I can ask the right questions.

22

I’m not surprised you’re confused - I must have written this too quickly - my apologies!
The first quote should read “No auto throttle engaged - haven’t seen an auto throttle switch for this aircraft yet, and I’m not using any switch I’ve mapped to engage auto throttle.” This in relation to the Daher.
At the time of throttle failure, autopilot IS engaged, mostly on the NAV switch and effectively ALT having used the VS switch for all height adjustments as directed by the controller. The failure occurs just on or after the controller instructs me to turn on final and contact the tower prior to landing. Wheels are down, with at least stage 2 of flaps.
This always happens on the Daher, and happened also on the Longitude. I will try say the Baron on a shorter route to see if the error occurs.
To answer other questions in no particular order:
Controller is a Saitek Yoke, Saitek Throttle Quadrant, and Thrustmaster Rudder Pedals (Saitek Rudder pedals stopped working three weeks or so ago, but I never got to use them on this sim). I don’t have any other add ons, and use the mouse for data entry and in-cockpit switch pulling!
To reproduce the failure, the following steps - Southampton to Charles de Gaulle, or Southampton to London City - file the plan after takeoff via the ATC window - follow all directions as given by controller - and failure occurs on final approach turn when directed to make the turn by controller. Last time, the failure occured at the same time as the controller vectored me without me touching any controls.

Experience level - apart from earlier shoot 'em ups like TFX, F22 Raptor, and Eurofigher Typhoon, my serious flight sim interest has been FSX, X-Plane 10 (which frankly I found abysmal) and X-Plane 11. Whilst I like to think I’m experienced, I know there are others better than me with greater knowledge. Having said that, I’ve not found any throttle failure like this in any of these previous three sims - unfair actually, because I rarely used the ATC in X-Plane 10 because it was just so awful!
I’ve not used any ATC add-ons.
I’ve used Orbx scenery add ons within X-Plane 11.

I will try the same route again with a different type of aircraft that doesn’t have the same sort of electronic MFDs that these two aircraft have.

Hope this post helps - and thank you everyone for your time in trying to help.

Edit - In addition, I can say that my PC is not all singing and dancing. However, it is good enough to run X-Plane 11 without this sort of catastrophic occurence. I feel the need for a graphics upgrade for both X-Plane and MFS2020. Had my PC have frozen due to graphic issues, I’d happily agree that the fault is my PC. However, I can’t quite correlate this failure to PC issues unless it’s a processing issue. I have 16gig of on board system memory, but shared graphics with an AMD Ryzen chip which I’d happily replace with the graphics upgrade!

23

Whenever I hear something like this my first thought is “mixture control”

I have read a lot of problems being caused by having “mixture control” bound to any axis. Especially aircrafts without a mixture control behave wired. Maybe that’s the case here too. Not being overly convinced this is your problem but maybe worth trying/checking.

24

@loveclose have you been able to get anyone else to reproduce the problem?

25

Mixture shouldn’t have any effect on a turbo prop. I had thought about this being an engine failure as well but I can’t make a correlation to control inputs and a fuel cutoff or starvation at a specific flight phase on multiple flights. But I am still leaning toward some key mapping issue.

@loveclose maybe try loading the default control map and see if this changes anything. Or on the left type in ‘fuel’ to get all the fuel related mappings to show and see what is bound. Maybe do the same filter with ‘throttle’.

I know you already dug through the control mapping but maybe using the filters you will see something you missed first time through.

26

when you say Daher i assume you mean the TBM 930? if this is correct ive done hundreds of hours on this aircraft in MSFS and ive never had this problem.
the TBM has no auto throttles and no mixture control it has a gear shift type throttle handle.
what i have noticed in this plane is that if you map a button to turbo prop reverse thrust in the TBM if you press it it actually just feathers the prop and you will hear the engine noise increase and the ITT shoot through the roof. cant think of any reason why this happens after you enter approach mode though as i say it has no way of controlling throttles
the only difference between nav and approach mode in this scenario is it will use pitch to follow the glideslope

27

Right. That is why this one is such a head scratch. It cannot be a setting in the aircraft. The throttle dropping to zero makes no sense. Even with autothrottle the power would not drop of as you turn final. With gear and flaps hanging out, if anything the autotrottle would increase power as you turn final. It makes no sense.

FYI if there is a control map available it is possible to have features that are not available on the aircraft simulate themselves with a key input. eg: deice on a 172

28

where does the throttle lever actually move to? as there are a few positions on that one

29

Something I hadn’t considered which may or not be relevant - flight plan adjustment.

Last third or quarter of the flight, I get directions to a waypoint - it’s never on my original flightplan. I then turn to my MFD, and enter the new waypoint ‘before’ the one I’m flying to. I have to add one more waypoint usually, and the flight proceeds until the last turn to the runway.

Is there anything in this that would cause the throttle to cut - some setting I’m missing whilst adding the additional waypoint?

Can’t try anything right now - 20 gig update just started!!!

30

Simple answer. No.

Only possible cause would be catching your sleeve on the throttle while adjusting the waypoints and pulling the throttle to neutral as you sit back.

Aircraft wise. There is nothing that would retard the throttle automatically. There must be a command being sent to the sim unintentionally. That is why I keep coming back to mappings.

So far no-one else has been able to replicate the same occurrence. This suggests something in your configuration.

31

@loveclose have you tried resetting all your control mappings to default? Including joystick, throttle, keyboard and mouse?

32

Not as yet - 4.5gigs of update out of 20 odd gig completed - can’t load the sim yet!!! I think I’ll try a few things this eve, and update again tomorrow as I reckon I won’t be able to load up for at least another hour and a half…
Thank you all for suggestions and support.
In reply to Puuhbearchen, I did find something mapped to mixture control - I didn’t recognise it, it did look like an axis. I have since removed it, but it didn’t solve the problem.

33

Late night update!!
I flew the London CIty route quickly to see how the update had fared - no issues after the update so all was well.
On this occasion, I filed the IRF before takeoff, not that I think that would make any difference.
I intended to fly the route I had mapped out irrespective of controller calls near to the destination.
I followed all altitude changes as requested.
Close to my turn point, the controller cleared my approach via another waypoint. I found the waypoint and it was way behind my position - is this normal in itself? I would have expected to have been cleared to that waypoint way before I went past it…
Anyhow, against my flight principles, I went on and ignored it.
Turned on to the final approach, expecting either the controller to clear me for landing, the throttle to fail, or both.
None of these things happened…
The approach was actually perfect - no throttle failure at all…switching to Nav1 and APR went smoothly, and we landed - albeit without clearance. I was expecting the rollocking from the ATC - didn’t happen.

I’m going to it again tomorrow - following all directions to see if I can replicate the problem again. However, the throttle didn’t fail due to any control mapping - surely it would have failed this time as well if it was due to mapping??

How can I check my frame rate - in X-Plane, real time flight was not easy because X-Plane is a real graphics memory grabber.
My frame rate in this sim seems better than X-Plane, but I couldn’t help wondering if I get out of real time synch (for want of a better expression) and the whole flight falls apart consequently???

Thoughts for the evening - I am going to check mappings thoroughly tomorrow as has been suggested, and will post screenshots if I get the throttle failure again…

Thank you again for all patience and support.

34

Another update…still not out of the woods, but more info…

Reflew in the Daher again.
This time, I specified the approach from within the Flight Plan screen - hadn’t done that before, was always on automatic previously.
So far, this was of course the smoothest flight with very precise ATC commands. Wish I’d known about specifying approaches before, but there we go…
Did all four sides of the approach and got the initial ‘contact the controller’ on the final turn - still ok this time!
Initiated the NAV1 and APR - worked just fine…and I’m thinking, ‘we’ve cracked it’.

Only to be scuppered by the final clearance from ATC, London City Control Tower. As soon as they game me landing clearance, bang with the throttle straight down to zero again, No response from the throttle possible again after that.

The flaps I have mapped to my throttle quadrant, and they worked still after throttle failure.

I’ve rechecked all mappings - still can’t see anything that looks dodgy - and in any case, the throttle failure did not occur when I pressed anything in cockpit or on my flight controls - purely on cue with the ATC controller.
I’ve attached a pic of the MFD to see if there’s anything that can be spotted that gives any clues.

In the meatime, I’ll fly it in the Baron which has different MFDs and control inputs to see if it does the same.

Screenshot (87)
Screenshot (87)1920×1080 238 KB

35

OK - last update for tonight! Interesting development, but still not resolved…
Southampton to London City flight - same Flight Plan as previously, but with the twin engined Baron.

Flight went very smoothly, until once again, final approach, and at landing clearance, throttles went straight to zero again. Nav1 was activated, but not by me. APR felt like it was activated, but the switch was still off. It was almost as if someone had taken control of the aircraft.

On this aircraft however, the throttle control would respond if I increased it - but wouldn’t sustain - would go straight back to zero. However, with this small spasmodic throttle boost available, I was able to kangaroo down to the runway and land.

During the descent, I was able to check the cockpit throttles - I’d move them, and they’d go straight back to zero - just like the flawed 2nd lesson where our beloved instructor talks at the start, the plane plummets towards the ground, and you have to stay alive by adding whatever boost you can whenever you can. When the instructor stops talking, throttle control returns. It feels exactly like that scenario here - control is taken over from you and throttle control lost when ATC gives final clearance.

Interestingly, after landing, full throttle control is functional again.

This smells of a bug of sorts surely?? If so, any known fixes - cos it feels just like that second flawed training lesson…

I’d add that if I did this exact flight without registering the IFR with ATC, and announced my intentions to land near to London CIty, this flawed throttle problem would not occur. I’ve flown it twice now with no problems at all. Only occurs if registered with ATC as an IFR flight.

36

Problem solved - Ladies and Gentleman, welcome to London CIty.
We hope you enjoyed flying Loveclose Airways.

I’m almost too embarrassed to reveal the actual cause of the problem…
Sing up if you would like to know, and I’ll reveal all!!!

:roll_eyes: :roll_eyes: :roll_eyes: :roll_eyes:

37

Glad you fixed your problem.

38

Thank you Mdapol for your time with this, and others. I feel as though I’ve wasted folks’ time with this after finding the cause if it all, but it wasn’t deliberate!

Apologies and thanks to everyone.

39

Glad you got this sorted.

It would be very helpful if you could post the fix so that others can benefit.

“Learn from the mistakes of others, you will not live long enough to makes them all yourself”

40

Ok, I shall bare my soul for all to see…!!!

The fix was sorting out confusion on my part. Up until the realisation that I didn’t have any sort of bug or problem, it really did feel like one.

Initially, the ‘problem’ was on all IFR flights. I’d ask ATC for IFR clearance, and away we’d go with no problems until the approach. As soon as landing clearance was given, the throttle went to zero every time, with no throttle response at all. This seemed like a massive issue, particularly as on non IFR flights using the APR aproach, there was no throttle control loss at all.

The Longtitude Jet displayed these ‘symptoms’ as did the Daher turbo prob. It wasn’t until I tried the same route with the Baron twin engined aircraft that I realised that it wasn’t a throttle cut, it was throttle control…I reckoned I had enough height to land with the throttle at zero, and all was progressing well. At one stage, I lifted the nose, and heard the engine note increase, indicating more power added. Which meant that the aircraft throttle was being controlled. I also subsequently found that trim was also not possible.
Remember that these symptoms were not happening on non-IFR flights!!!
I then thought that the bug or ‘problem’ was similar to the second flawed training flight where the instructor has control, and the power disappears, and you have to perform miracles to avoid crashing…well, it wasn’t that as it was at that point that I had the epiphany…

‘Assisted Landings’ was turned on in the preferences menu. With Assisted Landings, it appears that the sim takes over certain aspects of the landing such as throttle control, trim etc, making it easier for novices to land.

After twenty odd years of flight simming, I’d never seen ‘Assisted Landings’ settings before and didn’t even know such a setting existed in this sim.

So at the end of the day, I’m left red-faced having asked for help regarding a problem that didn’t exist. At least this post will point anyone else who thinks they have this problem in the right direction!!

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