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soldano

Autolanding speed

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I noticed that if I autoland the B777 at the FMC indicated aproach speed, it touches at an unusual high angle of attack, almost hitting the tail, so I must add almost 10/15 knots in order to land properly.- Is that an issue ?

Thanks

Jorge

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Is that an issue ?

 

Can you be a little more specific?

 

What is your weight? What is your approach speed? What is your angle of attack (or better yet, what is your pitch indication on the PFD)?

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No, I am using flap 25

 

Can you answer the questions I posted earlier?

 

?

Can you be a little more specific?

 

What is your weight? What is your approach speed? What is your angle of attack (or better yet, what is your pitch indication on the PFD)?

 

 

Also, real names are required to be added to your post:

http://forum.avsim.net/topic/245586-you-must-sign-your-full-real-name-to-posts-to-use-this-forum-posts-without-names-will-be-deleted/

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No, I am using flap 25

 

That's strange - autoland is available at F30 only in my aircraft (well and F20, but that's for single-engine)

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That's strange - autoland is available at F30 only in my aircraft (well and F20, but that's for single-engine)

 

If not properly configured, that might be part of the cause, honestly.

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I think Kyle has hit on your problem. Likely carrying too much weight for landing. Check your fuel and payload settings and dial them back. Try a test flight around the airport using 75 per cent payload and 25 tonnes of fuel and see if that makes a difference for landing. Also make sure you are using the approach speed.

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Just want to add that you are supposed to use the FMC indicated landing speed +5 knots as your target speed in the MCP.

 

Mike

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No Autoland with flaps25....see limitations chapter L.10.6!

 

(That does not mean that I am saying PMDG has simulated autoland with flaps 25 correctly or not.....no idea......but try a flaps 30 autoland).

That's strange - autoland is available at F30 only in my aircraft (well and F20, but that's for single-engine)

Not sure what you mean by available...?

 

If you keep the AP engaged I think it will try to do an autoland even with flaps 0.

(or at least....I have never heard of a feature that will disengage the AFDS when you approach the rwy with no flaps).

But I imagine that the AFDS is not programmed to properly flare and retard thrust at the resulting speeds and descend rates to make it a "nice" landing.

Which is why there is the limitation to use flaps 20 and 30 only.

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Not sure what you mean by available...?

If you keep the AP engaged I it will try to do an autoland even with flaps 0.

 

Yeah, it will do so, of course, well.

 

bdEFXlN.jpg

 

Still. 

 

 


L.10.6

 

Also, the NO AUTOLAND announced on PFD. That's what I meant.

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Also, the NO AUTOLAND announced on PFD. That's what I meant.

I was not trying to tell you one should try autolands with flaps 0. I was just trying to explain what I think the system would do.

 

 

You get NO AUTOLAND if you approach with flaps 25?

 

Interesting....I have never done a normal landing with flaps25 (but maybe for a non normal in the sim) so I would have to look up if that message should be there or not when you land with flaps 25,15,5,1,0

 

Could be...makes sence too.

 

In that case.....Mmm. I guess Idle, flare and rollout mode will never engage and thus autoland is not available at all.

 

but in that case the OP must have tried an Autoland with flaps25 while having NO AUTLAND on his PFD??

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In that case.....Mmm. I guess Idle, flare and rollout mode will never engage and thus autoland is not available at all.

 

That they aren't announced doesn't mean they aren't armed or won't actually activate...

As I said,

 

bdEFXlN.jpg

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That they aren't announced doesn't mean they aren't armed or won't actually activate...

As I said,

 

bdEFXlN.jpg

(I can do without the pictures.)

 

Yes that is exactly what it means!

 

Once below 1500ft RA you should get Flare and Rollout (white=armed).

If you do not get that, but get the NO AUTOLAND message instead....then those modes will not activate or arm or engage or whatever.

 

see FCOMv2 page 4.10.16

That's strange - autoland is available at F30 only in my aircraft (well and F20, but that's for single-engine)

Also,

 

Flap 20 is not just for single engine!

 

Flaps 20 is used often for single engine landings, but also for many other non normal conditions.

 

And single engine you can land with flaps 30 as well.

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Flap 20 is not just for single engine!

Flaps 20 is used often for single engine landings, but also for many other non normal conditions.

And single engine you can land with flaps 30 as well.

 

Fair enough, might be company specific, the info I was coming from.

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Gentlemen,

 

I understand that I should use flaps 30 and Vref+5 for landing, but what value should the Vref take?

 

Should I use the value shown by the INIT REF or deduct some for the consumption between setting Vref and expected landing time (in my procedure I try to set up for landing around 1 hr prior, so set for 7 tonnes less fuel)?

 

Cheers, Richard

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Gentlemen,

 

I understand that I should use flaps 30 and Vref+5 for landing, but what value should the Vref take?

 

Should I use the value shown by the INIT REF or deduct some for the consumption between setting Vref and expected landing time (in my procedure I try to set up for landing around 1 hr prior, so set for 7 tonnes less fuel)?

 

Cheers, Richard

Generally you should set up for landing after commencing descent. Fuel burn after that will be minimal. You should use the speed shown on the APPR REF page. You could do all your other planning and preparation in advance and leave Vref till later. Much better than doing it early and calculating a correction due to fuel used. If you forget to set Vref the system will prompt you to do so later on.

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Yeah, it will do so, of course, well.

 

Still.

 

Also, the NO AUTOLAND announced on PFD. That's what I meant.

NO AUTOLAND means the autopilot is not capable of autoland. At around 1500' AGL it does a series of checks to confirm status and annunciates LAND3, LAND2 or NO AUTOLAND. The flap setting at that time might not yet be the final landing flap.

 

The autopilot is capable of auto landing at flap 25, it just isn't certified to do so.

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NO AUTOLAND means the autopilot is not capable of autoland. At around 1500' AGL it does a series of checks to confirm status and annunciates LAND3, LAND2 or NO AUTOLAND. The flap setting at that time might not yet be the final landing flap.

.

Yes....so you agree with my initial thoughts that flap setting is not included in those check right?

 

I too cant remember having ever seen the NO AUTOLAND message just because of not being completely configured.

Maybe I have a few minutes later on to see what the PMDG does when you approach with flaps 25....(or even flaps5).

 

There are many things that are not warned for by the 777.

People overestimate how perfect the 777 is.......it is a great aircraft but the PIC still has to know his stuff.

That "fail safes fail safes everywhere" does not allways fly....not even with the 777!

 

Many things rely on local rules and regulations that cant be known to the 777.

For exemple the equipment that is required to fly a NAT track......if something failes there you do not get an UNABLE NAT message or something like that.

The PIC just has to know that NAT is not allowed without certain equipment and act accordingly (fly below NAT or request rerouting or land at enroute alternate).

Examples are:

2 ND

2 PFD

Autopilot

MCP panel

ADIRU

2 FMC

2 CDU

ETC..

 

Or if something of the required ground equipment for autoland fails you dont get a NO AUTOLAND message either.

Examples are:

Runway light system inop

RVR measuring system inop

ILS standby transmitter inop

 

And there is on board equiment that can fail that does not give you a NO AUTOLAND caution.The following are examples of things that do not cause the NO AUTOLAND message to show even though you (or we with our SOPs) can not do an autoland.

Flaps not at 20 or 30

Anti Skid system inop.

Auto callout function (50,30,20,10)

Auto Throttle (required for CatIIIB but not for CatIIIA)

Capt window heat

Capt windshield wipers

etc.

 

Of course we dont have to remember everything.....we just have to remember that when something failes that we look in the tables in the back of our company QRH and see if CATIII or autoland capability is effected.

The autopilot is capable of auto landing at flap 25, it just isn't certified to do so.

I am not sure if that is so.

 

You are definately correct that Autoland is only certified with flaps 20 and 30.

But capable.....or not capable.....I dont know.

 

For example in the FCTM you can read that Autoland is not certified and not recommended when overweight.

But then it mentions that in case of emergency.....if determained the safer course of action.....an autoland can be done even if overweight as long as all systems and instruments are closely monitored during the autoland.

So at least it is mentioned that this can be done.

I dont think it is mentioned anywhere that an autoland could be done (even though not recommended) with flaps 5 for example.

 

As I said previously....I dont think the NO AUTOLAND message comes for a non autoland flap setting. So rollout and flare would arm if you ask me, and the AFDS will attempt to autoland I think.

But capable in the sence of a safe landing (no structural damage...no long long flare etc)......I am not so sure about that.

Gentlemen,

 

I understand that I should use flaps 30 and Vref+5 for landing, but what value should the Vref take?

 

Should I use the value shown by the INIT REF or deduct some for the consumption between setting Vref and expected landing time (in my procedure I try to set up for landing around 1 hr prior, so set for 7 tonnes less fuel)?

 

Cheers, Richard

We allways enter the expected landing weight on the CDU APPROACH page.

This is true for normal landings (early descend preparation) but also when we have to do a non normal checklist that results for example in Vref30+15 or so. Even if we do this hours before landing.....the estimated landing weight is used.

 

I Just take a look at landing fuel (progress page) and present fuel on board.

The difference is our estimated burn till landing.

On the APPROACH page you overwrite the current weight with your estimated weight and then you select the resulting calculated Vref30.

(this weight overweight is temporary.....if you leave the APPROACH page and go back to it you will see that your actual weight is in there again, but Vref30 is still as you selected previously).

Shortly before landing (on final usually) I take a quick look if my estimated weight and Vref was correct or has changed (holding).....and update Vref (even if only 1kt different) if required..

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Hi Rob,

 

I shall alter my 'habit' to:

 

"I Just take a look at landing fuel (progress page) and present fuel on board. The difference is our estimated burn till landing. On the APPROACH page you overwrite the current weight with your estimated weight and then you select the resulting calculated Vref30".

 

Many thanks

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You are welcome Richard :-)

 

I guess there are different ways of doing it (company SOPs).

 

The thing that matters in the end is that you fly the correct Vref speed for your weight.

When you set it really does not matter as long as you dont forget to update Vref if required (for example if you just select the current Vref for your current weight a coule of hours before landing....lthen that is not wrong per se. But you do have to remember to update that before you land later).

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Still...in most cases where I've selected VREF at T/D, it's only changed by a knot at the most by the time I'm closer in. If you think about it, VREF increases with weight and the fuel load only decreases the weight, so if you're a knot on the high side, you're just adding distance from the stall margin. In other words, it's not unsafe to not update it, or forget it. You just might float a little bit.

 

I actually use the method Rob outlined earlier by using the PROG page to help get a more VREF, but even without it, it's generally only a knot or two off on the high side.

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Still...in most cases where I've selected VREF at T/D, it's only changed by a knot at the most by the time I'm closer in. If you think about it, VREF increases with weight and the fuel load only decreases the weight, so if you're a knot on the high side, you're just adding distance from the stall margin. In other words, it's not unsafe to not update it, or forget it. You just might float a little bit.

 

I actually use the method Rob outlined earlier by using the PROG page to help get a more VREF, but even without it, it's generally only a knot or two off on the high side.

yes correct.

 

The biggest discrepancy is usually caused by a non normal that requires fuel dumping to not land overweight. If you enter Vref at present weight as per non normal checklist and then dump fuel....then the updating becomes more important.

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For your info, some of the latest 773ER is certified for flap 25 autoland, due to the increase use of flap 25 landing as part of the fuel saving measures. As far as I know for Cathay airplanes it starts from B-KQO, so I assume airplanes being made around the same time should have the same certification provided it is not an airline option.

 

Like Kyle had already mentioned, it's not that the airplane can't do it, it just the amount of certification work involved to get it done.

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Yes....so you agree with my initial thoughts that flap setting is not included in those check right?

 

I too cant remember having ever seen the NO AUTOLAND message just because of not being completely configured.

Maybe I have a few minutes later on to see what the PMDG does when you approach with flaps 25....(or even flaps5).

 

There are many things that are not warned for by the 777.

People overestimate how perfect the 777 is.......it is a great aircraft but the PIC still has to know his stuff.

That "fail safes fail safes everywhere" does not allways fly....not even with the 777!

 

Many things rely on local rules and regulations that cant be known to the 777.

For exemple the equipment that is required to fly a NAT track......if something failes there you do not get an UNABLE NAT message or something like that.

The PIC just has to know that NAT is not allowed without certain equipment and act accordingly (fly below NAT or request rerouting or land at enroute alternate).

Examples are:

2 ND

2 PFD

Autopilot

MCP panel

ADIRU

2 FMC

2 CDU

ETC..

 

Or if something of the required ground equipment for autoland fails you dont get a NO AUTOLAND message either.

Examples are:

Runway light system inop

RVR measuring system inop

ILS standby transmitter inop

 

And there is on board equiment that can fail that does not give you a NO AUTOLAND caution.The following are examples of things that do not cause the NO AUTOLAND message to show even though you (or we with our SOPs) can not do an autoland.

Flaps not at 20 or 30

Anti Skid system inop.

Auto callout function (50,30,20,10)

Auto Throttle (required for CatIIIB but not for CatIIIA)

Capt window heat

Capt windshield wipers

etc.

 

Of course we dont have to remember everything.....we just have to remember that when something failes that we look in the tables in the back of our company QRH and see if CATIII or autoland capability is effected.

Yes, the LAND3 logic checks the autoland system itself. Three A/Ps engaged, each with isolated power supplies. Each channel cross-checked with the others and within tolerance. Three valid independent sources for ILS and Rad Alt, etc. Things like flap setting aren't important to that logic, which is about fail operational performance. As you said, the A/P will attempt to land even with no flap.

 

Just to be sure this is how PMDG modelled it, I tried a flap 25 autoland earlier, setting flap 25 and Vref25 well before 1500' AGL. It annunciated LAND3 and landed without any problem.

 

I am not sure if that is so.

 

You are definately correct that Autoland is only certified with flaps 20 and 30.

But capable.....or not capable.....I dont know.

 

For example in the FCTM you can read that Autoland is not certified and not recommended when overweight.

But then it mentions that in case of emergency.....if determained the safer course of action.....an autoland can be done even if overweight as long as all systems and instruments are closely monitored during the autoland.

So at least it is mentioned that this can be done.

I dont think it is mentioned anywhere that an autoland could be done (even though not recommended) with flaps 5 for example.

 

As I said previously....I dont think the NO AUTOLAND message comes for a non autoland flap setting. So rollout and flare would arm if you ask me, and the AFDS will attempt to autoland I think.

But capable in the sence of a safe landing (no structural damage...no long long flare etc)......I am not so sure about that.

The autopilot is a closed loop system. As such it is self-compensating. It doesn't usually need specific control laws for a given flap configuration. So if it can autoland at flap 30 and flap 20 it's highly likely it can do it at flap 25. What hasn't been done is any certification testing to demonstrate that it performs within FAA/EASA tolerances. Hence flap 25 wasn't certified for use. According to the post before this it has now been certified on some -300ER aircraft. This is basically an economic issue. Boeing won't spend money testing both normal flap configurations if one will suffice. Now the additional certification work has done due to economic pressure. Presumably any operator who wants to use flap 25 will have to pay Boeing for the privilege. There may be an FCC software update as well (to fine tune performance as necessary).

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