cagrikartal

Recycling the Flight Directors

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Hello everyone,

I wanted to ask pmdg if is there a fix coming for flight directors. When you recycle the flight directors, you reset the autopilot and annonciator so the directors on PFD  should disappear which is not the case in pmdg 747/737/777. However this is in 737 i presumed it would be the case for the 747 as they share the same philosophy.

Take Care

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39 minutes ago, cagrikartal said:

I wanted to ask pmdg if is there a fix coming for flight directors. When you recycle the flight directors, you reset the autopilot and annonciator so the directors on PFD  should disappear which is not the case in pmdg 747/737/777. However this is in 737 i presumed it would be the case for the 747 as they share the same philosophy.

Elaborate, please.

When I cycle the F/Ds, the behave as they should.

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38 minutes ago, scandinavian13 said:

Elaborate, please.

When I cycle the F/Ds, the behave as they should.

When you disconnect the autopilot on final for example, you swich the FDs on and off again so that the directors clear on the fd and the autopilot modes are ready for a go around. The reason to do that is to fly the final without an erronous fd indications on pfd after having passed a non-precision minima.

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This procedure sounds like something made up to get around a problem that no longer exists.  I sure do not see this in any of the Boeing documentation.  You have sources?

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7 minutes ago, cagrikartal said:

When you disconnect the autopilot on final for example, you swich the FDs on and off again so that the directors clear on the fd and the autopilot modes are ready for a go around. The reason to do that is to fly the final without an erronous fd indications on pfd after having passed a non-precision minima.

If you have supporting documentation and steps to reproduce, I think you've been around long enough to know that these kinds of assertions should go directly to support:

support.precisionmanuals.com

Still, I'm not quite clear as to what the issue is, in terms of what you think should be happening, versus what is happening.

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I dont have documentation for now but i tought it was known  and clear, tested it on a levelD but anyway.  I will try to find the docs. 

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16 minutes ago, cagrikartal said:

I dont have documentation for now but i tought it was known  and clear, tested it on a levelD but anyway.  I will try to find the docs. 

"When you recycle the flight directors, you reset the autopilot", sorry that is not correct.

Please read this regarding 747:

Flight Director (F/D) Switches

The left F/D switch activates F/D steering indications on the left primary flight display (PFD). The right F/D switch activates F/D steering indications on the right PFD.

ON -

  • on the ground with no autopilot (A/P) engaged and both F/D switches OFF, the first F/D switch positioned ON arms the F/D in the takeoff go-around (TO/GA) roll and pitch modes. Positioning the second F/D switch ON displays the flight direction steering indications on the second PFD

  • in flight, with the A/P disengaged and both F/D switches OFF, the first F/D switch positioned to ON activates the F/D in:

    • vertical speed (V/S) as the pitch mode, and

    • heading hold (HDG HOLD) as the roll mode, or if bank angle greater

      than five degrees, attitude hold (ATT)

  • in flight, with the A/P engaged and both F/D switches OFF, the first F/D switch positioned to ON activates the F/D in the selected A/P mode(s)

    OFF -

  • F/D steering indications do not display, unless

  • a TO/GA switch is pushed when airspeed is greater than 80 knots and flaps out of up

 

 

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Hi all,

During my technical Boeing 747/767/777 avionics training i learned that if you switched off the flight directors
you've got a total AP/FD reset. so i think it is a correct observation from cagrikartal.
Sorry my technical training document are distroyed 😞

Regards
Jo va Bra

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44 minutes ago, downscc said:

This procedure sounds like something made up to get around a problem that no longer exists.  I sure do not see this in any of the Boeing documentation.  You have sources?

Dan, actually this happens from time to time and we turn off FDs and APs and back on to clear whatever went wrong. I agree it's not a common situation but it might happen from time to time.

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killthespam wrote:

"in flight, with the A/P disengaged and both F/D switches OFF, the first F/D switch positioned to ON activates the F/D in:

vertical speed (V/S) as the pitch mode, and

heading hold (HDG HOLD) as the roll mode, or if bank angle greater

than five degrees, attitude hold (ATT)"

This is correct you didn't want a FD signal what is wrong with the actual sitution (within limits). The FD is synchronising the actual situation within the limits about heading and V/S

Regards

Jo va Bra

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Posted (edited)

Hi. AME here ;).

Sorry if you see the word "Figure" here but the not the Figure it self can't be copy-paste them according to my own limitations.

Hope this post solves the Problem.
[MOD: Copyrighted text removed.]







Best Regards.

-S.

Edited by scandinavian13
minor correction

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Thats poor form. We can all read manuals.

This thread wouldve been better served if you rationalised the text instead of lazily slopping that lot onto the pile.

Please refrain from copy and pasting boeing text verbatim and provide references instead. 

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13 hours ago, cagrikartal said:

When you disconnect the autopilot on final for example, you swich the FDs on and off again so that the directors clear on the fd and the autopilot modes are ready for a go around.

I am not even close to being an expert in the B737 systems but what little I do know is that the AFDS is quite different to the B744. I do seem to recall seeing this as a B737 procedure, but certainly not on the B744, because the B744 FDs will engage in HDG | VS and you will indeed have...

13 hours ago, cagrikartal said:

erronous fd indications on pfd

The only time I have ever known it appropriate to "cycle" the B744 FDs on approach is if you need to get out of LOC | GS (e.g. because ATC have offered you a sidestep to a different runway etc). This is because disengaging the autopilot and turning off the FDs is the only way to get out of APP mode without performing a go around. Having got back to HDG | VS you can then re-tune the ILS for the new runway and go back to APP or whatever new mode you wanted.

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RW 747 ops: after taking the autopilot out you can either leave the FDs on and follow them for guidance from the ILS or RNAV, or if you prefer to go visual the FDs can be turned off.

Hitting TOGA in a go around will bring the FDS back in TOGA modes if they’ve been turned off. Then once you select a mode other than TOGA on the go around the FDs will disappear again.

I’ve never heard of the procedure of recycling the  FDs as described on the 744, it must be from other Boeings.

cheers

Jon Bunting 

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3 hours ago, Copper. said:

provide references instead

Read the top ! I have already mentioned the Reference !
AMM - Chapter 22 !!


Regards
-S

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59 minutes ago, Samany69 said:

Read the top ! I have already mentioned the Reference !
AMM - Chapter 22 !!


Regards
-S

The manuals are copyrighted... copying prohibited. Calm down please.

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2 hours ago, Samany69 said:

Read the top ! I have already mentioned the Reference !
AMM - Chapter 22 !!


Regards
-S

Don’t construe my words. They are to be read in entirety. I reiterate:

“This thread wouldve been better served if you rationalised the text instead of lazily slopping that lot onto the pile. Please refrain from copy and pasting boeing text verbatim and provide references instead.”

This isn’t the first time you’ve done this sort of thing.

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25 minutes ago, Copper. said:

Don’t construe my words. They are to be read in entirety. I reiterate:

“This thread wouldve been better served if you rationalised the text instead of lazily slopping that lot onto the pile. Please refrain from copy and pasting boeing text verbatim and provide references instead.”

This isn’t the first time you’ve done this sort of thing.

I‘ve just had a little private conversation with Samany. I think he has understood your intend on asking for reference and him refraining from copy and paste now. He didn‘t mean to get on anyone‘s nerves with it and just wanted to help 🙂

everything‘s fine 😄

back to the evil flight director‘s cut

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When doing a non precision approach it is recommended in our FCTM that the FD's are switched off when you go visual as they will indicate misleading (yet highly compelling) commands. However, in the event of a go around, if both FDs are off, when an APFDS mode is selected the thrust will go to full go around thrust and potentially destabilise what would otherwise have been a nice go around. Hence...

Our FCTM suggests when visual on a non precision approach the PNF turns both FDs off then turns his back on again.

The only other time FDs are switched off (as has already been mentioned) is when you are trying to break out from LOC/GS; AP off, FDs off, it's the only way (other than a go around).

I don't own the PMDG QOTSII (yet), only the old FS9 version so I've no idea what this model does and couldn't possibly comment on its accuracy.

Our aircraft are not very "standard" (from screenshots, our autobrake selector is in a different place and we have a master FMC switch) as 744s go so we may have issues that other operators don't and hence have slightly non standard procedures.

However, that's what we do IRL,

HTH

Ian Webber

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2 hours ago, iwebber said:

However, that's what we do IRL,

Interesting Ian, while I understand this I question the need.  I mean, after all, you have gone visual so the piloting is based on the external and runway environment.  Sure, the FD might command a pitch up at the MDA  if it was set up that way but surely the pilot is well trained and is not going to follow that false queue?  About the only information I need from within in that stage of flight is airspeed..., maybe I'm not understanding.

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2 hours ago, downscc said:

Interesting Ian, while I understand this I question the need.  I mean, after all, you have gone visual so the piloting is based on the external and runway environment.  Sure, the FD might command a pitch up at the MDA  if it was set up that way but surely the pilot is well trained and is not going to follow that false queue?  About the only information I need from within in that stage of flight is airspeed..., maybe I'm not understanding.

Nope. You understand with clarity. I was thinking the same thing too.

I can only imagine there was a bug, or incident or accident that caused Boeing to add that procedure.

FWIW, I never cycle them, even on circling approaches which is the specific FCTM procedure that prescribes the cycling of fd’s. I just look through steering commands unless going around at MDA/MAPt.

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Posted (edited)
4 hours ago, downscc said:

Interesting Ian, while I understand this I question the need.  I mean, after all, you have gone visual so the piloting is based on the external and runway environment.  Sure, the FD might command a pitch up at the MDA  if it was set up that way but surely the pilot is well trained and is not going to follow that false queue?  About the only information I need from within in that stage of flight is airspeed..., maybe I'm not understanding. 

I see where you're coming from and I wouldn't say it's dangerous not to or poor airmanship either way, it's simply the airline policy that if you're not going to follow the FD, turn it off (at any time, not just on the approach - unreliable airspeed jumps straight to mind). Mainly it's so the other guy can monitor you more effectively (don't forget it's a multi crew aircraft and effective CRM suggests having both pilots at the same level of SA).

They wouldn't have just made this up so there must have been a number of issues with people getting distracted by or subconsciously following the FD when they shouldn't be. While you're looking outside most of the time when you're visual, you'll also scan the instruments (speed, power, pitch - the jumbo is very pitch sensitive on approach, VSI, wind readout, any other number of bits of information that are in front you). A FD that's slightly up, down, left or right will be noticed (by design) and send a subconscious message to you to make that correction, it's what you do/what happens 99% of the time, so I totally see how it could occur, particularly in times of high workload, or acute stress, or low arousal levels, or simply a moments inattention, or a distraction, or any other of the millions of reasons aeroplanes crash.

The training is great but it doesn't change the fact we're human with all the failings and frailties that brings. The way we protect ourselves (and our 350 passengers and the people on the ground around us) from those failings is a safety system that picks up and feeds back these sorts of issues when they occur, they can then be classified and analysed in the safety of a nice warm office, risks can be assessed and recommendations given. Finally SOPs can be modified (or created) to reduce the risk factors. It's a slow process and it's not very manly but it saves lives (and, of course, millions and millions of pounds).

2 hours ago, Copper. said:

I can only imagine there was a bug, or incident or accident that caused Boeing to add that procedure.

I don't think it's Boeing's procedure, I think it's ours, and yes, I suspect almost every section/rule in the FCOM and FCTM could have a date and some initials by it detailing a time and a pilot who didn't do whatever this rule says and came a cropper. That's how/why SOP's/FCOM's/FCTM's are created.

I'm just adding another perspective of real life here, I'm not trying to tell anyone how to fly their aeroplane or what's good/bad or right/wrong, just saying what we (1 fleet of 1 company) do IRL.

Hope this helps,

Ian Webber

Edited by iwebber
Clarity
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Posted (edited)

Personally I find the FDs distracting enough when I'm following them (which requires flying through them to an extent in any event for smoothness and accuracy) let alone when they're displaying something totally at odds with what is actually required.

To some extent in a large jet one is flying pitch and power datums even if the outside reference is 'primary' and not having the PFD cluttered with even more useless information for me at least certainly aids accurate flight! 

Furthermore in some modes and types not following the FD commands can lead you in to some pretty unpleasant situations if a distraction takes your attention away from monitoring other parameters (thinking Asiana for one). If you want a really powerful example of a pilot trying to follow inappropriate FD indications, watch back the AF447 FDR readout and look at the pilot inputs every time the FD pops up.

In short: I am a committed supporter of the idea that if you aren't going to follow it or it's not going to give you useful guidance, switch the damn things off!

Edited by skelsey
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Posted (edited)
On 7/10/2018 at 4:00 PM, iwebber said:

When doing a non precision approach it is recommended in our FCTM that the FD's are switched off when you go visual as they will indicate misleading (yet highly compelling) commands. However, in the event of a go around, if both FDs are off, when an APFDS mode is selected the thrust will go to full go around thrust and potentially destabilise what would otherwise have been a nice go around. Hence...

Our FCTM suggests when visual on a non precision approach the PNF turns both FDs off then turns his back on again.

 

Hi Ian,

 I’m not quite following this FCTM recommendation , I’m sure there’s a clever trick in there which is worth knowing , but I can’t see why you would get full GA thrust on selecting another APFDS mode or why having a FD on would prevent this?

cheers

Jon Bunting 

edited to add..

I can see that it might be useful in preventing both FDs from disappearing once selecting something other that TOGA on a go-around  but I’m still confused about how this would have any effect on the thrust.

Edited by jon b

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21 minutes ago, jon b said:

I’m sure there’s a clever trick in there which is worth knowing , but I can’t see why you would get full GA thrust on selecting another APFDS mode or why having a FD on would prevent this?

Me too, I'm not going to pretend to be an expert in the aircraft and all it's foibles, people far cleverer than I have reached this conclusion and I'd suggest at least one poor crew has had the pants scared off them in a go around. From what I've heard people say, it's something to do with the sequencing of thrust modes, FD on it goes to CLB, FD's off it goes to THR, that's the limit of my knowledge... I'm just a pilot. I don't know if it's a bug or a feature, I just know which one I'd prefer.

I've decided it's a mistake I don't want to make so I'm just going to do as I'm told and I'll ensure at least one FD is on whenever I do a go around, I've only two pairs of uniform trousers and one of them has shrunk in the wash (honest) so I've become quite attached to the other.

Sorry I can't be more helpful,

Ian Webber

 

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