744 Forum

Apron => Hangar 7 => Topic started by: Hardy Heinlin on Wed, 21 Aug 2019 17:46

Title: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Wed, 21 Aug 2019 17:46
Good evening,

we know, on the legacy FMC the altitude constraint windows are displayed without a space:

12000A17000B


On the 767 Pegasus I just saw a space between the numbers:

12000A  17000B


Does anybody know whether the 748/744 NG FMC also inserts a space?

(The modifications just never end ...)


Thank you!

|-|ardy


(I wouldn't rely on the illustrations in the manuals; they don't always agree with the real screens.)
Title: Re: 748 / 744 NG FMC cosmetics
Post by: emerydc8 on Wed, 21 Aug 2019 21:12
Hardy, check out this video. Where the AB FL and speed is involved there are no spaces, maybe because there is no room. But look at 00:35. There are spaces. Could it be that only where room is available there are spaces? The addition of FL might take up the space so there is no option to have spaces there.

https://www.youtube.com/watch?v=R8IlOOCWUNA&feature=youtu.be

Jon
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Thu, 22 Aug 2019 03:09
You're right. And my random example above wasn't quite correct; what I really saw was this:

250/15000B_9000A

So it simply inserts the same amount of leading spaces for the second number as it does for a single number.

E.g. for a window between 90 and 50 feet it will insert 3 spaces before either number:

250/___90B___50A

I guess the legacy 744 FMC does the same. Just nobody ever saw such low numbers on the real deck.

The current PSX versions always display such windows in the most compact form:

250/90B50A

However, PSX does insert spaces for single numbers:

250/___90B


Regards,

|-|ardy
Title: Re: 748 / 744 NG FMC cosmetics
Post by: emerydc8 on Thu, 22 Aug 2019 05:24
I'm sure 99% of the pilots couldn't tell you if there were spaces or not -- Stuff we look at every day but don't notice details like this.
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Thu, 22 Aug 2019 16:32
Another cosmetic area:

The NG FMC has a new ATC LOGON page that allows more manual entries in fields that are otherwise propagated from other pages:

TAIL NO  <-- from FMC memory  Edit: in legacy FMC too
ORIGIN  <-- from RTE page
DESTINATION  <-- from RTE page

Does anyone know whether these fields are displayed in small font when they are not manually entered?

The airport entries propagate from the RTE page to the LOGON page, but not vice versa. So it might be nice to get some visual feedback by small/big font changes.


Regards,

|-|ardy
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Sat, 24 Aug 2019 19:55
Regarding the new FIX INFO page:

The NG FMC allows pilot defined PBD and PBPB waypoint entries on the FIX INFO page in 1L. On the LEGS page such entries get a suffix with a sequence number, and the PROGRESS page in 4L always uses the suffix "00". I'm wondering what suffix the FIX INFO page uses. I guess it uses "00" as well.

E.g. VENUS180/55 will be displayed as VEN00 probably.

On the other hand, if you have entered 4 different PBDs of VENUS in the four FIX INFO pages, it would be nice if they were distinguishable on the ND. But the sequence numbers are reserved for the LEGS and shouldn't be used for off-route fixes. Perhaps they get letters?

VEN0A
VEN0B
VEN0C
VEN0D


Regards,

|-|ardy


Edit: I just learned how the suffix is designed on the 787 FMC. It's a dash and the page number, e.g. VEN-4. It's certainly the same on the 748 FMC.
Title: Re: 748 / 744 NG FMC cosmetics
Post by: mark744 on Tue, 3 Sep 2019 18:58
Quote from: Hardy Heinlin on Sat, 24 Aug 2019 19:55
Regarding the new FIX INFO page:
.......................................................


Edit: I just learned how the suffix is designed on the 787 FMC. It's a dash and the page number, e.g. VEN-4. It's certainly the same on the 748 FMC.

Same on the NGFMC 744
Rerards
Mark
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Thu, 5 Sep 2019 04:20
Thanks!


|-|ardy
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Thu, 10 Oct 2019 01:11
We know, for the landing flaps 25/30, the pilot or the NG FMC sets the flap related VREF plus wind-correction (which is entered on the APPROACH REF page at 5R).

Do you pilots (respectively does the NG FMC) add this wind-correction also to the other flap speeds, i.e.

VREF + 20 + wind corr
VREF + 40 + wind corr
VREF + 80 + wind corr
etc.
?

Is this airline specific?

Assuming no ATC intervention. How do you set the flap 20/10/5/1 speed bugs manually when you're not using the FMC? Do you add any wind correction there as well?



Regards,

|-|ardy
Title: Re: 748 / 744 NG FMC cosmetics
Post by: emerydc8 on Thu, 10 Oct 2019 02:01
QuoteDo you pilots (respectively does the NG FMC) add this wind-correction also to the other flap speeds, i.e.

No. Not at any airline I've flown for. Unless you're landing at flaps 20 due to an abnormal, then you would make the additions.
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Thu, 10 Oct 2019 02:19
Thank you.
Title: Re: 748 / 744 NG FMC cosmetics
Post by: mark744 on Thu, 10 Oct 2019 10:52
Quote from: Hardy Heinlin on Thu, 10 Oct 2019 01:11
We know, for the landing flaps 25/30, the pilot or the NG FMC sets the flap related VREF plus wind-correction (which is entered on the APPROACH REF page at 5R).




In our company, the wind corrected speed is not entered into the FMC.
The speed in the FMC is the one the FMC calculates based purely on pilot entered landing weight and desired flap
( unless the QRH instructs modifying the FMC speed and or flap setting  )

The wind corrected value is only set via the MCP 'bug'

Do any other companies put the wind corrected figure into the FMC?

Regards,
Mark
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Thu, 10 Oct 2019 12:28
According to the information I have, the default wind correction in the NG FMC is 5 kt (displayed in small font). If you want to get zero, you need to enter "0" (big font).

I now understand that the FMC adds this value to the flap 25/30 speeds only.

The NG FMC uses the VREF + wind correction for performance predictions on the final approach leg. It doesn't make a big difference; just a few seconds and some drops of fuel. That's not even within the display range. For a continuous descent down to the FAF, the NG FMC expects the flap 20 speed at the FAF.

Theoretically, it could also be used for VNAV approaches when the MCP SPD window is still closed (before it automatically opens by the on-approach mode activation). When a flap point on the ND is passed and you set the respective next flaps with the flap lever, the NG FMC automatically sets the next flap related command speed. When you set flap 25 while the MCP SPD window is closed, I think the NG FMC will set the FMC command speed to flap 25 speed plus wind correction. I have to reread that part. Maybe this automation only works down to flap 20.


Regards,

|-|ardy
Title: Re: 748 / 744 NG FMC cosmetics
Post by: mark744 on Thu, 10 Oct 2019 13:14
Yes, that's how I think it is too.

So the Vref dispalyed in the FMC is the Vref without any wind correction, and the +5 in small font is informing you that in VNAV (and speed window closed), the VNAV will use a target of +5 onto the Vref

That is, the Vref in the FMC does not include the +5

Mark
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Thu, 10 Oct 2019 14:50
Exactly.

It would be interesting if the FMC were to add the value to the flap 20 speed already. This way it could be already integrated in the earlier flight phase before the MCP SPD window opens. If it's only applied during the time when the window is open, the speed bug will be manually set anyway. What remains is a tiny ETA/fuel adjustment on the last 4 miles. Really tiny. That's why I wondered whether the wind correction is already added to flap 20 speed etc.


|-|ardy
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Jeroen Hoppenbrouwers on Thu, 10 Oct 2019 23:13
I think it may not really be the purpose of that feature to save a coffee cup of fuel. It is more likely that it reminds pilots in a nuanced way that there shall be a wind correction to the final approach speeds, and offers a spot where to put that. Fill in the complete landing form. Oh yes, wind correction.

And then it may help to get the speeds set up automagically on the MCP when you go intervention/override, one less possibility to forget the wind correction.

Hoppie
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Gilad on Fri, 11 Oct 2019 20:26
Hey Hardy.

Any update on the due date of the NG FMC? :)
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Fri, 11 Oct 2019 21:19
Hopefully this year.


|-|ardy
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Gilad on Sat, 12 Oct 2019 07:26
Thanks!
Title: Re: 748 / 744 NG FMC cosmetics
Post by: dhob on Sun, 13 Oct 2019 03:29
Quote from: Hardy Heinlin on Thu, 10 Oct 2019 12:28
Theoretically, it could also be used for VNAV approaches when the MCP SPD window is still closed (before it automatically opens by the on-approach mode activation).

This isn't accurate. The MCP window must always be manually opened when in VNAV, both for the Legacy FMC and NGFMC.
The NG FMC is "On Approach" when the flaps are out of up, which has two primary implications for VNAV.
The MCP altitude has no affect on VNAV PTH descent if MCP altitude is more than 300' from aircraft altitude, and;
If airplane is below VNAV PTH, and in approach logic, commands level flight in VNAV PTH until reaching the path.

The wind additive on the APPROACH REF page is only applied to the VERF entered, either Flaps 25, Flaps 30 or a NNC VREF (FLAPS DRIVE etc.)   

It is Boeing procedure to open the MCP speed window no later than the final approach segment, but that is for the Legacy FMC as well as the NGFMC. I don't believe they have reconsidered this for operators who are now all NGFMC. If the MCP speed window is left closed throughout the final segment, then an entered wind additive would make sense. However, for large wind additives, the final approach speed would be higher than FLAPS 20 speed. In this case the speed would slow to FLAPS 20 speed then accelerate to final approach speed when in landing configuration.
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Sun, 13 Oct 2019 04:43
Sorry, I didn't mean to write "automatically opens by the on-approach mode"
but "it automatically opens by G/S or G/P capture". (And there are some more conditions; see below.)

I guess most pilots will never get into this phase with a closed window, hence nearly nobody is aware of it. Or Boeing's FMC notes are incorrect.

This is a quote from Boeing's Differences Document:

Quote
7.2. G/S or G/P Capture

(NG FMC) With autopilot and autothrottle engaged and the IAS/MACH window closed or blanked, when G/S or G/P captures, the IAS/MACH window will automatically open and the pilot will set the appropriate speed.

(NG FMC) During manual flight with autothrottle disengaged and the IAS/MACH window closed or blanked, capturing the G/S or G/P will not open the IAS/MACH window since there is no A/T mode active.

(747-400 Legacy) For G/S capture, the 747-400 Legacy FMC operates the same as the NG FMC. The Legacy FMC does not have IAN capability and does not support G/P.
Title: Re: 748 / 744 NG FMC cosmetics
Post by: dhob on Sun, 13 Oct 2019 04:56
Yes of course, speed window opens whenever pitch mode changes to a mode other than VNAV.

Since the post was related to the wind additive on the Approach Ref page, I assumed it was in reference to a NON-ILS approach using VNAV to minimums or End of Descent.

If VNAV isn't the active pitch mode with speed window closed, the FMC speeds have no efficacy whatsoever.
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Sun, 13 Oct 2019 05:35
As far as I understand it, this text is about VNAV approaches with VNAV PTH, especially about IAN approaches with VNAV PTH. So, not a mode change, I think.

Note this part in the middle of the above quote:

"(NG FMC) During manual flight with autothrottle disengaged and the IAS/MACH window closed or blanked, capturing the G/S or G/P will not open the IAS/MACH window since there is no A/T mode active."

If this note were about a mode change, the window wouldn't open when engaging V/S or G/S etc.
Title: Re: 748 / 744 NG FMC cosmetics
Post by: dhob on Sun, 13 Oct 2019 19:48
First, the NGFMC itself does not enable Integrated Approach Navigation capability. The 747-8 has IAN capability due to different FCC's, and upgraded displays which display NPS and IAN scales. The FMC OPC must have the IAN and NPS enabled as well. With all this, the 747-8 uses an FMC generated glide path to create an ILS like display and approach. As such, to capture and fly an approach using IAN procedures, the APP switch is selected which arms the lateral mode (FAC, LOC or B/CRS) and pitch mode (G/P). One captured, G/P becomes the active pitch mode, and the auto throttle mode becomes SPD, and the speed window is opened when captured from VNAV PTH/SPD/ALT. All of of our 747-8's have IAN capability.

The 747-400 cannot fly IAN approaches. Boeing would have to retrofit the 747-400 with the requisite equipment, then accomplish certification with the FAA and issue an updated AFM. No operator has done this nor likely too as the cost benefit isn't there.

With that said, the only method to fly Non-ILS approaches in the 747-400 is with VANV PTH or V/S. For our procedures, we use VNAV (unless it simply isn't available). As stated in a previous post, VNAV PTH is the pitch mode throughout the approach, and the crew must open the speed window manually at some point prior to the FAF. Note all of our 747-400's now have NGFMC's with BP4.0 software.

The reference document you are referring to is a bit vague, and it conflates IAN with NGFMC. Further, the statement; "During manual flight with the autopilot disengaged, the autothrottle disconnected and the IAS/MACH window closed, capturing the G/S or (G/P for the NG FMC) will not open the IAS/MACH window since no A/T mode is active." is not complete. Boeing ends the paragraph with; "Manual flight with the autopilot disengaged, the autothrottle disconnected and IAS/MACH window closed is not a Boeing procedure."

No one would operate the airplane in VNAV with autopilot off and autothrottles off and speed window closed. The FMC would be commanding the speed bug without crew input or awareness, which could cause significant issues.

To reiterate, if VNAV is the active pitch mode, and a mode other than VNAV is subsequently captured or selected, the speed window opens.
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Mon, 14 Oct 2019 06:45
I agree with almost everything you wrote. But what you wrote does not resolve that bizzare Boeing text which implies that the window won't open automatically (under the conditions mentioned in the middle part of the text). If you assume they talk about a non-VNAV mode, then the window won't even open while a non-VNAV mode is engaged (in that case).

I understand that the SOP is to open the window manually long before. But I'm just interested in the system logic, i.e. in the question what will happen when VNAV remains engaged and the crew won't open the window manually.


QuoteNo one would operate the airplane in VNAV with autopilot off and autothrottles off and speed window closed. The FMC would be commanding the speed bug without crew input or awareness, which could cause significant issues.

The issues would be particularly significant when the A/T is engaged. That might be a reason why the window opens automatically in the final phase, in case the crew forgets it. So in the most critical phase the FMC can no longer change the speed bug to an erroneous setting which the autothrottle would chase. In manual flight you have at least your hands on the throttles and your eyes on the speed tape, so you see where the limits are even if the speed bug goes to a nonsense position.
Title: Re: 748 / 744 NG FMC cosmetics
Post by: United744 on Wed, 23 Oct 2019 01:45
From what I've seen of the 7_3_7 NG and 777, the speed window auto-opens at the current speed passing the FAF if it isn't already open. The "gotcha" is if you're faster than flap speed and decelerating, and running the flaps out. It will capture a higher speed, and could bust the flap speed (if that's what you were doing at the time). This is why Boeing recommend you manually open it prior to the FAF.

The wind additive is applied to the approach page VREF speeds. It's not an aide-memoire; it actually adds to the displayed speeds. What it won't do is update the selected approach ref speed - you would need to down-select the speed again.
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Fri, 12 Feb 2021 18:37
Further cosmetics:

Only recently I noticed on a real FIX INFO page that flight level values have leading spaces before "FL" when the level is below 100:

FL  8
FL 50
FL190


In PSX:
FL8
FL50
FL190


I think these leading spaces for lower FL values should be inserted on all FMC pages, not just on the FIX INFO pages.

Does anyone disagree?

(I know, flight levels below 1000 feet are not used in real life, but it's possible to set the TA/TL in the FMC below 1000. The display format should be consistent.)


Regards,

|-|ardy
Title: Re: 748 / 744 NG FMC cosmetics
Post by: dhob on Fri, 12 Feb 2021 19:49
Altitudes must be entered as 3, 4, or 5 digits. Regarding the legs page, if for example the transition level was 5000 such as EDDK, then if 7000 is entered on the legs page, it would display as FL070. Hypothetically, for the three flight level altitudes 70000, 7000, and 700, they would display as FL700, FL070, and FL007 on the legs page. The fix page I'm not sure, I'd have to check but not sure why it would be different. But I don't know for sure.
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Fri, 12 Feb 2021 20:16
Quote from: dhob on Fri, 12 Feb 2021 19:49
... display as FL700, FL070, and FL007 on the legs page.

Thanks, glad to hear. I like that better anyway, especially for AB windows:

FL060BFL050A looks better than this 3-piece fragmentation:
FL 60BFL 50A

The downselection in PSX already produces leading zeros, and the upselection too requires leading zeros. It was just the display format in the upper six page lines.

(I can't find that FIX INFO photo anymore. Perhaps it was an older FMC version.)




Leading zeros before "FL" are now implemented in PSX update 10.130. See item 130.03:

https://aerowinx.com/board/index.php?topic=4191.0


|-|ardy
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Tue, 20 Apr 2021 11:10
Hello,

as you all know, when you enter the destination runway on the REF NAV DATA page (INIT/REF INDEX > NAV DATA), line 3R will display the landing threshold elevation in feet.

In PSX (NG FMC & legacy FMC), the indicated value is rounded to the nearest 10. I think it shouldn't round it.

Also, I think, the length value indicated in 3L should subtract the displaced threshold distance from the total runway length if the entered runway is a destination runway. It does subtract it on the APPROACH REF page in 4L.

Any opinions?


Regards,

|-|ardy
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Mariano on Wed, 21 Apr 2021 01:15
Hardy,

Would a 767 Pegasus FMC check work?

I will fly again in less than two days. Just let me know.

Regards,

Mariano
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Wed, 21 Apr 2021 09:15
Yes, that would help. Thank you, Mariano.

Re runway length: I think it's correct if REF NAV DATA always displays the total length. Assume you will take-off and land on the same runway, and enter that runway on REF NAV DATA, the page won't know if it refers to the one or the other purpose. If it were to refer to the take-off before you take-off, and thereafter refer to the landing, the page would have to change the length display after take-off, and I think that would be a confusing feature :-)


Cheers,

|-|ardy
Title: Re: 748 / 744 NG FMC cosmetics
Post by: andmiz on Thu, 22 Apr 2021 04:03
 ???
Quote from: Hardy Heinlin on Tue, 20 Apr 2021 11:10
In PSX (NG FMC & legacy FMC), the indicated value is rounded to the nearest 10. I think it shouldn't round it.

Also, I think, the length value indicated in 3L should subtract the displaced threshold distance from the total runway length if the entered runway is a destination runway. It does subtract it on the APPROACH REF page in 4L.

Ran a quick test for you. 
On the real-world NGFMC it will round airport elevation to the nearest 10 feet. 
Runway 33 in ANC showed as 10865ft on both the ref nav data page and the approach ref page.  The TORA is 10865 for 33 but LDA is 10400, so it doesn't display the LDA. 
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Thu, 22 Apr 2021 09:24
Thank you. As you wrote "airport elevation": Did you enter an airport or a runway?

It's strange that the APPROACH REF page doesn't display the actual landing distance available. Did you do the test on the ground before takeoff? My theory: The takeoff/landing mode reference for the display will change when the half-route point is passed. Maybe not for REF NAV DATA page, but for the APPROACH REF page.

As we know, runway waypoints in the FMC database refer to the landing threshold (which may be displaced), i.e. the whole nav system is designed for landing. Now if the FMC always indicates the total length, it will disagree with the length shown on the ND.


Regards,

|-|ardy
Title: Re: 748 / 744 NG FMC cosmetics
Post by: andmiz on Thu, 22 Apr 2021 09:47
Quote from: Hardy Heinlin on Thu, 22 Apr 2021 09:24
Thank you. As you wrote "airport elevation": Did you enter an airport or a runway?

It's strange that the APPROACH REF page doesn't display the actual landing distance available. Did you do the test on the ground before takeoff? My theory: The takeoff/landing mode reference for the display will change when the half-route point is passed. Maybe not for REF NAV DATA page, but for the APPROACH REF page.


I tested with both the airport (PANC) and runway waypoints.  It was tested in-flight, but in the first half of the flight. 
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Thu, 22 Apr 2021 10:06
Quote from: andmiz on Thu, 22 Apr 2021 09:47
I tested with both the airport (PANC) and runway waypoints.

OK, so the rounded elevation display in PSX is correct. Thank you.


P.S.: It makes sense if the real FMC doesn't show the true landing distance: The real FMC obviously doesn't know the displaced threshold distance (otherwise it could suggest it in small font on the TAKEOFF REF page for the TOGA/FMC position update point). So the real FMC can always just indicate the total length which is stored in the FMC database. Nevertheless, the stored runway coords are landing threshold coords. And I guess the real ND generates the runway strip symbol simply by using the FMC's two landing threshold locations (actually the same as in PSX). So the ND automatically shows the landing distance rather than the total distance.
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Markus Vitzethum on Thu, 22 Apr 2021 12:44
Hi Hardy,

> The real FMC obviously doesn't know the displaced threshold distance

just as a quick reminder ... we previously discussed this particular item in the past, see this message from 2016:
https://aerowinx.com/board/index.php?topic=3713.msg38407#msg38407

Quote:
"The FMC runway database does store the landing threshold position. (...) It also stores total length and the offset of the threshold." (this refers to the real world 747-400 Navigation Database).

Markus
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Thu, 22 Apr 2021 13:02
Hi Markus,

thanks for the confirmation.

Now that raises another question: The ND gets the landing threshold coords from the FMC. If the reciprocal runway has a displaced threshold, the ND cannot show the entire distance from the active landing threshold to the other end.

AAAAAAAAAA BBBBBBBBBBBBBBBBBBBBBBBBBBBBBB CCCCCCCC

AAA = Front displaced threshold distance (not in database)
BBB = ND runway strip
CCC = Reciprocal displaced threshold distance (not in database)

The FMC knows the sum of AAA+BBB+CCC, but it doesn't know the  ratio of AAA/CCC, i.e. it doesn't know where they start and end.


Regards,

|-|ardy
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Markus Vitzethum on Thu, 22 Apr 2021 13:33
Hi Hardy,

I *believe* it is simpler ... I always thought that the FMC only cares about 1 runway which is the one and only runway which is loaded into the flight plan or the data page. I don't believe it takes into account the opposite runway (e.g. consider EDDF - there is a runway 18 but *no* runway 36 exists!)

So, assume a runway pair 15/33:

For runway 15:
- it knows AAA (offset, stored in the database) and BBB+CCC (length LDA, stored in the database).
  It does not load data for 33.

For runway 33:
- it knows CCC (offset, stored in the database) and BBB+AAA (length LDA, stored in the database)
  It does not load data for 15.

Does that makes sense?

Markus

Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Thu, 22 Apr 2021 15:37
Yes, got it. But I wonder why the real APPROACH REF page shows the total length rather than the LDA. The page is about landing performance.



P.S.:

Confusing ... confusing ... confusing ...

For PANC 33, the real FMC doesn't show the LDA (10400); it shows the total length (10865).

Theory A: The FMC knows both LDA and total length. (Why on the approach ref page it shows the total length rather than the more interesting LDA, nobody knows; maybe it's a bug.)

Theory B: The FMC doesn't know the LDA, thus it cannot show it by design (not a bug).
Title: Re: 748 / 744 NG FMC cosmetics
Post by: Hardy Heinlin on Thu, 22 Apr 2021 21:12
APPROACH REF now shows total length in PSX 10.134:

https://aerowinx.com/board/index.php?topic=4191.0


Regards,

|-|ardy