Autothrottle

[Guest wfr]

Hi!I was in cruise at FL330 in LNAV/VNAV (latest version) and did some tests with the A/T.1) I switched the A/T button on the MCP off -> A/T disconnected as expected.2) I cycled the A/T button back to on -> I expected that the A/T to engage - but nothing.3) Pressing the VNAV button re-engages the A/T ! That's wrong.Another problem: It seems that the cruise altitude update on the PERF page doesn't work anymore (pressing the ALT button on the MCP)GreetingsWalter

[DescendDescend 25]

I think it is correct. The MCP switch arms and disarms the A/T. To acivate it, a mode that requires autothrottle needs to be selected. At least that is my understanding of new feature: 17) Autothrottle disconnect but remain armed state logic (NEW) -- Right click on TO/GA "screw" in the air -- AT reactivated byre-selecting a pitch/thrust mode

[Guest wfr]

Hi Howard,When A/T mode annunciation is blank and current pitch mode is VNAV or FLCH, cycling the A/T arm switch to OFF, then back to A/T ARM should engage the autothrottles. This is not the case. Instead pressing the VNAV button engages A/T. This is wrong in my opinion.Walter

[crvm 0]

You said nothing about FLCH in your first post. If you are in VNAV and select the A/T to OFF on the MCP you lose VNAV so one has to switch the A/T back on and re-engage VNAV. As for being in FLCH and turning off the A/T, that I am not sure about. If on the other hand the A/T FMA status is blank yet VNAV is armed and you engage the A/T VNAV should ENGAGE.[h4]Randy J. Smith[/h4]AMD 64 4000+|ASUS K8V DELUXE|SAPPHIRE ATI X800XT PE|MUNCHKIN 3200|80 gig SATA|DELL 1905FP 19" LCD|TRACKir PRO|PFC JEPPESEN MOONEY YOKE|CH PRO PEDALS|

[crvm 0]

>Hi!>>I was in cruise at FL330 in LNAV/VNAV (latest version) and did>some tests with the A/T.>>1) I switched the A/T button on the MCP off -> A/T>disconnected as expected.Yes but it also disconnected the current picth mode which is dependant upon the A/T, in this case VNAV. >>2) I cycled the A/T button back to on -> I expected that the>A/T to engage - but nothing. Into what would the A/T engage into? The A/T would simply do what it always does in the absense of a armed picth mode i.e. ARM.>>3) Pressing the VNAV button re-engages the A/T ! That's>wrong. No this is correct. 1, you killed the A/T and active pitch mode. 2, You ARMed the A/T. 3, You engaged a picth mode in CMD in this case VNAV which then becomes ACTive.>>Greetings>Walter[h4]Randy J. Smith[/h4]AMD 64 4000+|ASUS K8V DELUXE|SAPPHIRE ATI X800XT PE|MUNCHKIN 3200|80 gig SATA|DELL 1905FP 19" LCD|TRACKir PRO|PFC JEPPESEN MOONEY YOKE|CH PRO PEDALS|

[Guest wfr]

Hi Randy,To make things clearer, I'll try to describe the problem once again:Annunciations reads as follows:SPD | LNAV | VNAV PATHAction: A/T ARM switch to OFFReaction: A/T disconnects - OKAnnunciation: [bLANK] | LNAV | VNAV PATHAction: A/T ARM switch to ONReaction: NothingAnnunciation: as aboveA/T should go back to SPD modeAction: pressing VNAV buttonReaction: A/T mode back to SPD (surprise!)Error 1) A/T doesn't re-engage cycling the A/T ARM switchError 2) You cannot reengage A/T by pressing the VNAV switch.Hope this helpsWalter

[Mats_J 2]

Walter,This is exactly how I understand it works from what our drivers tell us. Flipping the A/T ARM switch arms the A/T but no active mode yet.Pressing any SPD, FLCH or VNAV will re-activate the apropriate A/T mode.Maybe Alex or Jon can shed some light on this but as far as I know this is correct behaviour.Hope it helps,

[crvm 0]

Action: A/T ARM switch to OFFReaction: A/T disconnects - OKAnnunciation: | LNAV | VNAV PATH I'm sorry you lost me here. How can VNAV be "active" wihout the A/T engaged??EDIT: Appears something different going on than I know here. I am wondering if there is different airline configs related to VNAV without the A/T?? The PMDG is clearly holding VNAV without the A/T "ON". Systems wise I was under the assumption that without the A/T one would have F/D guidence only so must look into what I am missing here..[h4]Randy J. Smith[/h4]AMD 64 4000+|ASUS K8V DELUXE|SAPPHIRE ATI X800XT PE|MUNCHKIN 3200|80 gig SATA|DELL 1905FP 19" LCD|TRACKir PRO|PFC JEPPESEN MOONEY YOKE|CH PRO PEDALS|

[crvm 0]

Ok just talked to a real 744 pilot on the team, my assumption was wrong. You can have VNAV without the A/T! [h4]Randy J. Smith[/h4]AMD 64 4000+|ASUS K8V DELUXE|SAPPHIRE ATI X800XT PE|MUNCHKIN 3200|80 gig SATA|DELL 1905FP 19" LCD|TRACKir PRO|PFC JEPPESEN MOONEY YOKE|CH PRO PEDALS|

[Guest wfr]

Hi Mats,You're right saying that the A/T ARM switch arms the A/T.But...if A/T is active (SPD mode) and you switch it off and back on -it should become active again.Note: VNAV is active...in the PMDG747 pressing the already active VNAV button engages A/T again! I tried the situation also in PS1 and it confirmed my assumption.Maybe there is a new logic behind this or a company option.Just wondering.CheersWalter

[Mats_J 2]

Walter,With all due respect. As Randy stated some posts below here we have spoken with our real world drivers as do the dev team and what you see is what the real world drivers see.And with all respect to PS1. But sometimes it has it wrong too you know. ;-)Cheers,

[jon b 2,047]

Hitting VNAV will should re-engage the A/T.If you look on the MCP at the speed dial you will see 4 white lines coming from the dail.1 is to the speed window,the other 3 are all pointing to the mode switches that will engage the auto throttle-SPD FLCH and VNAV.regardsjon