Automatic Landing Cross Bar Behaviour

[tim96]

Hi all,

can someone tell me the reason why the crossbar on the PFD disapear by touchdown when i do an automatic landing? When i do a manual landing, the crossbars will stay on the PFD after landing and rollout. I checked the chapter in the manual- Automatic Flight, but i don't understand this behaviour. If someone is able to tell me, i would be very glad.

Thank you very much for answering in advance!!!

Best Regards

Volker
EDDK

[John H Watson]

This is a customer option. I've only heard of some airlines from the USA using this option.

See Model/Programming option "No FD if A/P on same source" on the Instructors Page

Rgds
JHW

[tim96]

Hi John,
thank you for your quick reply. I tried  what you said with different models and the programming , but everytime the crossbars disapear by tochdown and speedbrake action. As i said  it before it is only by  automatic landing. When i disconnect the AP before landing  the crossbars stay on the PFD. Has anyone an idea?

Best Regards
Volker

[John H Watson]

Sorry, perhaps I misunderstood you.

My manuals just say that if the autopilot is not multi-channel engaged, the roll mode (during rollout) is LOC. I'm not sure what the pitch mode is for rollout with the A/P disconnected. It may be G/S, but the G/S signal may be unreliable as the ground antenna will be behind the aircraft: The pitch mode may blank as shown in this video:
https://www.youtube.com/watch?v=TImK-oNY6-s&feature=youtu.be&t=3m5s

For Autoland, my manuals say that the roll mode is ROLLOUT (the F/D bars will be directing the aircraft to maintain the localizer centreline). The pitch mode during Autoland rollout is shown as blank in my manuals. I'm not sure what the flight director pitch bar is doing, but the autopilot servo command is to keep the nose down.

As always, manuals and big simulators may differ from real life.

Rgds
JHW

[John H Watson]

You can see the G/S mode disappearing in this manual landing video. I can't tell if the pitch cross bar disappears though.

https://www.youtube.com/watch?v=KuotSv56-LM

[emerydc8]

For Autoland, my manuals say that the roll mode is ROLLOUT (the F/D bars will be directing the aircraft to maintain the localizer centreline). The pitch mode during Autoland rollout is shown as blank in my manuals.

Here's a video I took of a friend getting his first leg of harassment OE going into VIDP. https://youtu.be/Y1wkV1eynMU

If you play this on a big screen you can see it much better (not bad, though, for a Blackberry camera). On landing, FLARE appears on the FMA pitch mode with the box around it. It looks like as soon as the aircraft touches down, the FMA pitch window goes blank. Since there is less than 10 seconds from the time FLARE goes active to the touchdown, the box around FLARE remains until FLARE disappears at touchdown. It's hard to tell, but it looks like the F/D pitch bar disappears on touchdown too. Of course, when you reverse, the A/T disengages and the A/T FMA also goes blank. So, during the rollout, all you wil see on the FMA is ROLLOUT.

[John H Watson]

Perhaps Hardy can take a look at this when he returns. The roll bar appears to remain in view in both circumstances.

Rgds
JHW

[tim96]

thanks again for answering and the good videos. It's really hard to tell what the bars do, but thanx for the support. This Forum is great and so helpful!!! I mentioned what John said, in the manual of PSX in the chapter Automatic Landing by rollout the bars are gone, may it has to be??? I tried to do some research in the net, and i found different statements. In one source it said, it would be normal that the bars disappers by automatic landing and in another one it would be wrong. If i remember well, the behaviour was in PS 1.2 too, but not in PS1 ? May it is a good idea to wait what Hardy will say.

Best Regards
Volker
EDDK

[Hardy Heinlin]

Hi,

this seems to be airline specific; e.g. in Lufthansa manuals, on the sample PFD for the ROLLOUT phase, the FD bars are completely removed.

I'm willing to modifiy this in a future update if we know for sure that this is either company specific or a new standard on all models.

For manual rollout, both roll and pitch bars remain in view. This is the case in PSX, in manuals, and in those videos (see https://www.youtube.com/watch?v=KuotSv56-LM at the end on the F/O's PFD; the horizon line is magenta).


Cheers,

|-|ardy

[emerydc8]

Hi Hardy,

The aircraft in my Delhi video was s/n 26350, Japan Airlines 8906, delivered 1993.

Jon D.

[John H Watson]

Just found this in one of the Maintenance Manuals:

"(5) OPTION GROUP 3
(a) Full Time F/D
1) The F/D command bars are displayed if either or both flight directors are turned on
regardless of A/P channel engagement.
(b) F/D Auto On
  1) This provides for automatic F/D selection following a Go-Around initiated during a
manual approach.
(c) F/D Display on ROLLOUT
    1) F/D commands not displayed during ROLLOUT engage mode.
(6) OPTION GROUP 4
   (a) Single Source Autopilot
    Effectivity: zzz pre-SB 747-22-2197
    1) Autopilot will not engage with only one valid source of stab position and only one
source of IRS data.
    Effectivity: airplane xxx and airplane yyy POST SB 747-22-2197
    2) Autopilot will engage (single channel only) with only one valid source of stab position
and only one source of IRS data, only if that channel was a valid local stab position and
valid local IRS data.
"

These options are achieved by pin-programming on the back of the FCC equipment racks

[John H Watson]

Entered in error...

[John H Watson]

Hopefully my previous message didn't go through. After re-reading the wiring schematics and wiring diagrams there appears to be one program pin controlling Option Group 3 (but options within Group 3 are activated by further pin programming).

If this is so, then airlines such as BA, QF, KAL, and MAS do not have the FD inhibit during Rollout engage.

P.S. Note that rollout engage might only extend to the point where the A/P is disengaged. ... at which point one or both FD bars may return.

For the techies, ref SSM 22-10-02 Table 1, and WDM 22-11-12 (pins C12 [CUST OPT PIN 3] and E5 [BARRIER GROUND]). I don't have any pin numbers for the activation of FD inhibit during Rollout engage.

[Britjet]

Just out of interest I'll try it in the BA sim on Wednesday.
Peter

[John H Watson]

Thanks, Peter.
If the FD does disappear on your sim during rollout engagement, I'll have to come up with an alternate theory for the pin programming.

Perhaps it would be possible to check when the bars re-appear (if they do disappear)?

[tim96]

Gentleman,

thank you so  much for your support to answer my question.  @ Peter; i really like to know what will happen in the Simulator
@ Hardy; thank you also for reply. Most of the times i "fly" Lufthansa. So my question is half answerd @ John, thanks  for your very detailed information

Best Regards
Volker

[Britjet]

In the BA sim the crossbar remains throughout the automatic landing and subsequent autopilot disconnect.
It is also there all the time for a manual landing, of course.

Peter

[John H Watson]

Thanks, Peter.
This seems to match my interpretation of the Flight Control Computer pin programming shown in the BA wiring schematics/diagrams. Unfortunately, I don't have access to LH wiring diagrams to compare their pin programming.

I wonder if anyone has a copy of Air India's wiring schematics? 

Rgds
JHW

[Hardy Heinlin]

F/D removal is now optional in PSX 10.0.9-beta2:

http://aerowinx.com/board/index.php?topic=3685.0