morph10

Flight director off during approach (747)

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Hi

Would love to know does the flight director get turned off during approach (before landing) in case of a go around? As I am aware that you cannot turn off the approach button on go around when flight directors are still engaged.

Edited by morph10

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53 minutes ago, morph10 said:

Would love to know does the flight director get turned off during approach (before landing) in case of a go around? As I am aware that you cannot turn off the approach button on go around when flight directors are still engaged.

Same way you turned it on at the beginning of the flight: the F/D switch on the extreme left or right of the MCP.

Make sure to have a look at and fly the tutorial.

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But normally it only is turned off during a visual approach when the reference is your eyes. During any instrument approaches you use the FD for guidance. For a go around you would press the TOGA buttons on the thrust levers (index or middle finger in the real airplane) 

you would recycle the FD (off-on) to exit the app mode during an RNAV approach when you decent below the initial approach fix altitude and the PNF resets the MCP to the go around altitude. This way the FD bars don‘t provide any decent path info anymore (I THINK they assist you with pitch guidance for the speed set on the MCP) but in case of a go around you immediately have g/a pitch guidance.

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Thanks Ephedrin that makes more sense. 

The reason I ask was that yesterday I had to do a go around for the first time in the 747, the mistake I made was to manually apply thrust rather than pressing the TOGA button, as a result I could not disengage the APP mode until I turned off the FDs. 

So I take it that if I just press the TOGA button on go around this will automatically disengage the APP mode?

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3 hours ago, morph10 said:

So I take it that if I just press the TOGA button on go around this will automatically disengage the APP mode

Yes pressing toga will deactivate APP mode and the approach will be deleted from the fmc while you make your way to the Map missed approach point. Then you add the approach again and try it once more. 

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5 hours ago, morph10 said:

Thanks Ephedrin that makes more sense. 

The reason I ask was that yesterday I had to do a go around for the first time in the 747, the mistake I made was to manually apply thrust rather than pressing the TOGA button, as a result I could not disengage the APP mode until I turned off the FDs. 

So I take it that if I just press the TOGA button on go around this will automatically disengage the APP mode?

It's important that you understand the "language" of the airplane. The MCP buttons light up when a mode can be disengaged or disarmed by pressing that buton again. You might have noticed that "APP" lights up when you ARM it, but extiguishes as soon as the approach mode is active. this means you can't turn it off anymore (safety reasons). You have to either go around (TOGA button) or disconnect both flight directors. 

Edited by Ephedrin
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Thanks Sloppysmusic and Ephedrin for your help, it all makes sense now.

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8 minutes ago, morph10 said:

Thanks Sloppysmusic and Ephedrin for your help, it all makes sense now.

+++1 from me too.

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Welcome guys! A point to read up on in the manual is that sometimes even if the FDs are both OFF the plane will turn them ON for a climb following a Go AROUND or TAKEOFF. Pressing that TOGA button triggers a whole number of interesting processes. Enjoy !

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13 hours ago, Ephedrin said:

 You might have noticed that "APP" lights up when you ARM it, but extiguishes as soon as the approach mode is active

are you sure about that?   On the 744 ?   Not for me...

Edited by Sekkha

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Every Boeing 7x7 does that (except maybe the 717). As soon as the approach mode is active the light goes off. The lights do NOT mean, that a mode is active, it only means it can be switched off again. Armed or active is read from the FMA (above the artificial horizon). 

Edited by Ephedrin

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 we must be talking about different things....  :)

33093385288_593b7314a0_b.jpg

 

32027875647_206aef2df7_b.jpg

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On 2/2/2019 at 9:10 PM, Ephedrin said:

It's important that you understand the "language" of the airplane. The MCP buttons light up when a mode can be disengaged or disarmed by pressing that buton again. You might have noticed that "APP" lights up when you ARM it, but extiguishes as soon as the approach mode is active. this means you can't turn it off anymore (safety reasons).

Sorry, but this is simply not how it works, because the white light in the 744's MCP APP switch will remain on whenever the Approach Mode is active.

The  "language" of the Autopilot/Flight Director system (AFDS) is always determined using the FMA annunciations in each pilot's PFD and not by the lights in the MCP's buttons.  Pushing the APP switch arms/selects the AFDS in LOC and G/S modes and the white APP switch light will stay illuminated until the APP mode is deactivated in one of these possible ways:-

1) By pushing the APP switch a second time before LOC and G/S capture.

2) By selecting TOGA after LOC and G/S capture.

3) By disengaging the A/P and turning off both FD's after LOC and G/S capture.

4) By selecting a pitch mode other than VNAV when the G/S is captured and the LOC is armed.

5) By selecting a roll mode other than LNAV when the LOC is captured and the G/S is armed.

6) By selecting LOC mode when the LOC is captured and the G/S is armed (this then becomes a localiser approach).

7) By selecting LNAV, VNAV or LOC before the localiser and glideslope are captured.

20 hours ago, sloppysmusic said:

Welcome guys! A point to read up on in the manual is that sometimes even if the FDs are both OFF the plane will turn them ON for a climb following a Go AROUND or TAKEOFF. Pressing that TOGA button triggers a whole number of interesting processes. Enjoy !

Yes, if the Flaps are not UP and the airspeed is >80kts and they get even more interesting when TOGA is pressed a second time!

 

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The APP light bar on the MCP stays illuminated on the 757/767. Also, in order to get out of approach mode, not only do the flight directors need to be turned off but the autopilot must be off as well. I’ve never flown the 747 but I assume it’s similar to the 757/767. 

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A disturbing number of accidents in the real world have been caused because pilots did not understand what their systems were trying to tell them. We have had posters here flatly contradicting each other about the meanings of indicators while saying *exactly* the same thing. Instead of arguing your opinions, why don't you simply quote the manual? It might mean you would have to actually read it again and there is a risk that you might just learn something you didn't know before, but hey, what is life without a little risk?

Approach mode *can* be disconnect by pressing the APP button a second time, but only if certain other conditions are satisfied. Those conditions vary between different aircraft. Approach mode can be changed or disabled in other was as well, and yes, there are ways to turn the Approach mode off without disconnecting the FD's *if* certain other conditions are satisfied.  However, if you are on an approach that is going wrong, which is the usual time when you might want to turn approach mode off, and you *don't* know what those conditions are, or what your systems are telling you, then you will probably crash and burn and kill everybody on board, but hey, as I said, what is life without a little risk?

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8 hours ago, Paul_Smith said:

A disturbing number of accidents in the real world have been caused because pilots did not understand what their systems were trying to tell them. We have had posters here flatly contradicting each other about the meanings of indicators while saying *exactly* the same thing. Instead of arguing your opinions, why don't you simply quote the manual?

You are quite right, Paul. 

My previous post not only describes the importance of relying on the FMA annunciations to inform the pilots what the AP/FD system is doing, but it also lists the different ways APP Mode can be deactivated on the real B744; so why not try each one out for yourself in the QOTS II B744 and see for yourself?

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23 hours ago, Paul_Smith said:

 We have had posters here flatly contradicting each other about the meanings of indicators while saying *exactly* the same thing. Instead of arguing your opinions..

arent you doing exactly this ?

1 hour ago, Paul_Smith said:

Read the actual manual.

didnt Bertie list exactly the conditions which  the manual states ?

anything wrong about what he said ?

why continue arguing here ?

Edited by Sekkha

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On 2/3/2019 at 11:59 PM, berts said:

Sorry, but this is simply not how it works, because the white light in the 744's MCP APP switch will remain on whenever the Approach Mode is active.

The  "language" of the Autopilot/Flight Director system (AFDS) is always determined using the FMA annunciations in each pilot's PFD and not by the lights in the MCP's buttons.  Pushing the APP switch arms/selects the AFDS in LOC and G/S modes and the white APP switch light will stay illuminated until the APP mode is deactivated in one of these possible ways:-

1) By pushing the APP switch a second time before LOC and G/S capture.

2) By selecting TOGA after LOC and G/S capture.

3) By disengaging the A/P and turning off both FD's after LOC and G/S capture.

4) By selecting a pitch mode other than VNAV when the G/S is captured and the LOC is armed.

5) By selecting a roll mode other than LNAV when the LOC is captured and the G/S is armed.

6) By selecting LOC mode when the LOC is captured and the G/S is armed (this then becomes a localiser approach).

7) By selecting LNAV, VNAV or LOC before the localiser and glideslope are captured.

Yes, if the Flaps are not UP and the airspeed is >80kts and they get even more interesting when TOGA is pressed a second time!

 

I'm actually completely confused right now. I've always been completey sure about that when approach mode is entered you can't deactivate it anymore except by turning off the FD or engaging TOGA. Therefore I've never really paid attention to the MCP once I was on the ILS. I've read about this so many times just here in the PMDG forum (at least I'm also "sure" about this 😕 ) so I've never questioned this. 

Now, after your answer, I checked back in the sim with the 737 and the 777 (I don't have any 767 or 757 anymore) and it's actually the 737 only, that shows that behaviour: Once LOC and GS are captured you can't switch off app mode anymore by pressing any MCP button. You have to recycle the FD or press TOGA. 

In the 777 however you can disengage APP all the time, it simply switches over to HDG HOLD and VS with the present vertical speed selected. 

I don't need to try the 744 now, you've already made it clear..

 

So I think there has been any finding when designing the 737NG, which came after the 744 and 777, that has resulted in this "new" behaviour of the MCP/FD? Does someone know how it works on the 737 Classic?

Edited by Ephedrin

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3 minutes ago, Ephedrin said:

: Once LOC and GS are captured you can't switch off app mode anymore by pressing any MCP button.

thats the same on the 744, but the light stays on

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Just now, Sekkha said:

thats the same on the 744, but the light stays on

yep... so first you couldn't disengage APP anymore, then you could (777) and then again you couldn't, but the light turned off. 

So.. as the 787 shares a type rating with the 777 I suppose you can turn it off again? 747-8 too? or not? 

red thread - negative report... That's actually a completely confusing aircraft design. 

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9 minutes ago, Ephedrin said:

I'm actually completely confused right now.

That makes two

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31 minutes ago, Sekkha said:

arent you doing exactly this ?

didnt Bertie list exactly the conditions which  the manual states ?

anything wrong about what he said ?

why continue arguing here ?

I am not the one expressing opinions.

No, Bertie did not list the conditions in the manual.

Yes, there is something wrong with the opinions Bertie expressed. And there is something wrong with Marc's opinion of how things work, and there is something wrong with your opinion of how things work, but you don't need my opinion on it when you can just RTFM for yourself. 

The manual will tell you how Approach mode works for the aircraft you are on, but instead of asking how you disengage it, you should seriously consider when and why you might want to disengage it, and what it is you want to be able to do that requires it to be disengaged.

 

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4 minutes ago, Paul_Smith said:

And there is something wrong with Marc's opinion of how things work

that's not an opinion. That's false knowledge. My opinion right now is "unlogical and inconsequent aircraft design". But that wonÄt help anyone who finds himself in the situation to decide to go around or not to go around and what's done then.

Sure, everything is written in those manuals. And I agree with you, that buttons should be reviewed in the manuals, it would be faster and more definitive than writing in a forum. However questions like these have often led to good discussions from which people can learn a lot, all above when the actual pilots jump in.. Bertie is one of those flying the 747 for a living. When he states those conditions we can be quite sure that they are correct.

I personally am thankful right now that Marcus brought that topic up, otherwise I would have sticked with that wrong information. Now I will definitely go back to the FCOMs and FCTMs and look up those topics. Please, calm down a bit. 

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