cagrikartal

Recycling the Flight Directors

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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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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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Thanks Ian, most intriguing, I’m sure there’s something really useful there that I’ve never heard before.I’ll look into it when I’m not so tired as I am now.

You do right, keep your head down !

cheers

Jon Bunting

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On 7/11/2018 at 5:10 AM, iwebber said:

I don't think it's Boeing's procedure, I think it's ours

Just checked. It’s standard Boeing fleet procedure I think for circling approach only. Always good to keep abreast other operators procedures, reasoning and philosophies. Looks like air Asiana had fd cycle procedure for npa’s too, meant little to them.

in both air asiana and Air France cases, discipline is key and instrumental. Even now I still wonder why those accidents happened... they didn’t need to and shouldn’t have with a more disciplined crew.

cheers

Edited by Copper.

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On 7/9/2018 at 4:12 PM, 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.

 

Going back to the original question in this thread, I am not aware of anything wrong with the way the PMDG B744 Flight Directors are behaving. 

Although Erek is not quite correct in what he says (because both Flight Directors and the Autopilot(s) need to be disengaged at the same time), the procedure he has alluded to is a fairly common one on the real aircraft.  It is used whenever the aircraft is already fully established on an ILS approach and ATC subsequently clears it to land on a parallel runway.

Changing the landing runway after the aircraft is established on an ILS is not an ideal situation to be in, but at places like Los Angeles where it can be very busy with two parallel runways in use for landings at the same time, it is not unusual for ATC to switch aircraft from one runway to the other; especially when they are still a fairly long way from touchdown.    

Provided the aircraft is already coupled on the ILS LOC and G/S, then disconnecting the Autopilot(s) and turning off both Flight Directors is the recommended way to get the AP/FD system out of approach mode.  Only then should you turn the F/Ds back on again before re-engaging an autopilot.  Although it sounds complicated, it only takes a few seconds for the non-handling pilot to change the active runway in the FMS CDU and turn the F/Ds back on, while the handling pilot can either re-engage an autopilot or fly the aircraft manually.  This is usually done using the A/P or F/D in HDG and V/S modes in order to turn the aircraft towards the parallel runway's extended centreline whilst keeping the rate of descent going.  As soon as the new ILS is tuned and identified correctly the LOC and G/S modes can be re-armed and the ILS captured in the normal way so that the approach can continue to a safe landing on the parallel runway..

Bertie Goddard

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