AT and FD behaviour with the FD switches OFF

[John H Watson]

... and if you still have some free time, Peter.. .  ... would you be able to pull the "EIU L" circuit breaker on P7 (grid reference F9).

My notes are a little ambiguous regarding the Advisory message ">EIU LEFT". It's not clear if it should appear in the air.

Ta!

JHW

P.S. Um.. I hope the associated status message isn't latched 

[emerydc8]

Hi Peter,

If you get a chance, can you check and see whether you can get out of THR and into SPD once you do a TOGA intercept of an MCP altitude on a missed approach by pressing FLCH after ALT is active? I know your video shows you pressing FLCH then SPD (to get out of THR) just in case ALT has already captured. That is my understanding too, but my sim partner here on the 767 is a former 744 instructor and he is adamant that pressing FLCH after ALT captures will take it out of THR and into SPD -- at least on our 744 sim. He said he demonstrated this to every crew. It goes to SPD || FLCH SPD momentarily and when it realizes that it's at the MCP altitude it needs to be it goes back to ALT but stays in SPD. Maybe this is a sim-ism. I asked if this was the case before they converted over to the NG and he said it absolutely was like that with the legacy software too.

On the 767 low-altitude capture, after we see ALT CAP, the call is "select speed, speed," meaning dial in Vref30+80 and press the SPD switch to get it out of THR (N1 in this case). We are going into the 767 sim this morning and we will check it there too. I don't think FLCH will do anything for you to get you out of THR once you've captured an MCP altitude, but we'll see. I haven't purchased any edible socks yet though! Thanks!

Jon

[Britjet]

John and Jon..
Will have a go..
Peter.

[Hardy Heinlin]

I will have limited opportunity to check all if this today - but how does this sound?

Start of Take-off - FDs OFF. Derate entered.
Below 50kts - Press TOGA - observe FMAs
Above 80kt - Press TOGA again - observe FMAs
Below 400ft - Press THR - observe EICAS and FMAs.

Sounds good, but isn't the last item obvious anyway? THR cannot be engaged below 400 ft. Or do you want to check whether the THR switch removes the derate?

How does this sound?

Start of Take-off - FDs OFF. Derate entered.
Below 10kts - Press TOGA - observe FMAs
Below 30kts - Just in case any TOGA modes appear: Cycle both FD switches to ON and back to OFF
At 65kts - Check if THR REF changes to HOLD
Above 70kt - Press TOGA again - observe FMAs


Regards,

|-|ardy

[Britjet]

Sounds good.
Peter.

[Will]

Peter,

If you have time, I'm wondering if you could test some additional things.

Release brakes -- drink beer.
Above 50 kts -- press TOGA, drink another beer.
At 73 kts -- pull the "EIU L" circuit breaker on P7 (grid ref F9).
At 77 kts -- pull the Smoke Evac handle while performing a TCAS test.
At 104 kts -- use electrical tape to make a happy face on the ND.
At 113 kts -- sharpen the crash axe.
At 116 kts -- set MCP Alt to your postal code.
Below 26 feet -- exchange shoes with PNF.
Above 45 feet -- use electrical tape to make a happy face on the PNF.
Below 97 feet -- pick up crew interphone, sing the first verse of "Jerusalem"
Above 101 feet -- "your aircraft"
Above 102 feet -- "my aircraft"
Above 103 feet -- "your aircraft"
Above 104 feet -- "my aircraft"
Above 105 feet -- "your aircraft"
Above 106 feet -- "my aircraft"
Above 107 feet -- "your aircraft"
Above 108 feet -- "my aircraft"
Above 109 feet -- drink another beer

Thanks! :-)

[Britjet]

That sounds much easier..thanks Will!
Peter.

[emerydc8]

Just got back from testing the 767 sim. If I didn't see it myself, I wouldn't have believed it. On a missed approach, and after capturing an MCP altitude while still in THR, if you press FLCH, it takes it out of THR and into SPD mode. No need to press the SPD switch on the 767. Now I'm wondering if this was some sort of mod due to the potential trouble it could cause on an early level off.

[Hardy Heinlin]

I guess this is a logical side effect of a prompt FLCH -> ALT capture process, not an intentional replacement for the case when the crew forgets what the SPD switch is for.

Who would forget the SPD switch function anyway? "Captain, do you know how to engage the SPD mode?" -- "Not sure, try FLCH" :-)

[John H Watson]

I would advise caution when comparing the 767 to the 747-400. There are APFD mode and lots of FMC differences 

[Britjet]

Quick recap of my BA sim tonight..
I didn't get chance to video - too much going on - but..
Take-off - with derate...FDs OFF - pushing TOGA initially engages THR REF but no FD pop up and other modes remain blank. Further pushes at any speed on the ground have no effect.
THR REF changed to HOLD as expected.

Approach - with CLB selected as Thrust Limit - selecting flaps 1 - EICAS limit changes to GA, but this can be modified in the FMC page.
I didn't get chance to try landing Flap in isolation but my guess would be that it would be the same as GS capture which changed (previously selected) CLB mode to GA, and was locked - could not be changed - in FMC.

Pulling EIU left CB caused a blanking of Capt displays for about 2 secs and then the autochangeover occurred and restored them. EICAS SOURCE SEL EIU displayed and EIU LEFT status but no advisory.

I didn't get chance to try Jon's GA trick - I have another sim tomorrow and will try and fit it in..

No beer, sadly...

Peter.

[Hardy Heinlin]

Thanks a lot, Peter!

When you selected the CLB thrust limit during approach, was the FMC in ACT DES? When you change the flap setting in ACT CLB, GA will certainly not activate.


Cheers,

|-|ardy

[Britjet]

We were very much "mucking about" but I guess it must have been DES or it wouldn't have given me GA?
I will try and get a confirmed DES mode tomorrow.
So you are saying that in a normal after-take-off CLB mode after selecting flaps UP, and then reselecting flaps down, that you won't get GA mode? That would make sense..
Peter.

[Hardy Heinlin]

I don't know, I have no theory at all :-) But, yes, *if* GA activates at flaps-out in ACT CLB or CRZ, then it can only happen if the flaps have been up before. Otherwise you would get GA every time you change the flaps during departure.

If this is true, and you select flaps up and reselect flaps 1 during climb, say, at 6000 ft AGL,  e.g. due to an unexpected ATC reclearance with a lower speed limit, then your CLB thrust will suddenly change to GA thrust, and the nose will rise etc. -- Actually, I can't imagine this would happen.


|-|ardy

[emerydc8]

I didn't get chance to try Jon's GA trick - I have another sim tomorrow and will try and fit it in.

Thanks, Peter.
Jon

[Hardy Heinlin]

I have removed the condition of the pitch mode being engaged in TO/GA which enables the automatic change from THR REF to HOLD at 65 KIAS.

Now if the option "IDLE also engages on non-autoland" is installed, it will immediately change THR REF to IDLE when below 25 ft RA, i.e. during take-off.

This didn't happen before because the TO/GA pitch mode disabled it.

Now I need to disable that idle option when the pitch mode is blank. I.e. the idle option will not work when the FDs and A/Ps are off. Whether this is correct ... I don't know ...

Or I disable it when the A/T is in HOLD or KIAS is < 65.


|-|ardy

[Britjet]

Tried some more today..

In DES mode, flaps UP. Thrust mode CLB selected in FMC..
Select Flap 1 - EICAS thrust limit changes to GA. But this CAN be changed to another mode in FMC, unlike the GS capture case.

Manual landing with FDS off..Autothrottle engaged - SPD  annunciated on FMA - gradual flare down to touchdown - SPD Mode remained - I didn't notice if there was any thrust lever movement but I guess there would have been - Mode blanked only on actual touchdown.

Go-around - remaining in TOGA with auto level off in ALT - THR remained annunciated (of course) and speed increased to just below Flap limit, as expected. When exactly level - pressed FLCH - nothing happened. Pressed it again and got momentary "flash" of FLCH SPD, and then a second or so later got SPD and ALT. The impression I got that this was a possible slight altitude deviation permitting a short-lived FLCH mode, but not something that really should happen.
I can't imagine why anyone would want to demo this as a way of getting out of THR mode, Jon?
Best left alone, in my view..

HTH

Peter.

[Hardy Heinlin]

Thank you, Peter! This all agrees with PSX except for the GA lock when G/S is engaged. I'll add this to the next beta.


Cheers,

|-|ardy


P.S.: In the previous PSX versions, GA did activate when G/S engaged, but only if it had not activated before by flap extension. I.e. it didn't activate a second time in order to allow the pilot to select another mode.

Now I'm wondering how the FMC responds during GA lock when the pilot selects a non-GA mode. Will it quickly jump back to GA, or will it ignore the key press and show INVALID ENTRY? I vote for the latter.

[emerydc8]

Thanks for checking, Peter. I think this is hit-or-miss on using FLCH to get it out of THR once altitude captures from TOGA mode. It worked in Boeing's 767 sim but, like you said, it's hard to know if it's an aberration due to being slightly off altitude that allows a momentary FLCH to go active long enough to pull it out of THR and into SPD. Even on the 767 for an early altitude capture, while still in TOGA mode, we use the speed switch to get control of the speed and then select Vref30+80 to clean it up.

Sorry, Hardy, for injecting an unrelated subject into this string. I wonder where the cutoff is as far as being off altitude while in ALT that would alow FLCH to engage.

Jon

[Hardy Heinlin]

Maybe the same as in V/S: Below ALT and descending, or above ALT and climbing.


This trick includes an additional effect: FLCH will set the speed bug to the current speed if the bug is lower. Can this be of any advantage?


|-|ardy