A/T thrust mode question 744

[Guest joediamond]

>Actually, IMO, it's a hazard that an "AT Disconnect" switch>even exists. You should never be able to shut off the AT>system while the AP is engaged. (Note: Watch for the MD11. The>AT arm_disarm switch has been completely removed from the MCP.>The MD11 has it right. The 744 has it wrong . . but here we>are! So how do we deal with this?) Sam,There are plenty of jets flying that do not have an auto throttle system installed. Do these aircraft constitute a hazard in your opinion? Whatever the level of automation that exists in a particular aircraft the pilots still need to be flying the aircraft. If they are not competent enough to do so then that's the real hazard.The AP and AT are separate systems and should be treated as such. They operate in close coordination with each other but each is capable of operating without the other. The AP will fly the aircraft just fine without the AP it will just require the pilot to, well be a pilot. The "what-if" scenarios you describe assume a complete lack of situational awareness by the pilots and are not realistic in the real world.Respectfully,C McCarthy

[Jeff Nielsen 1,386]

None the less, is anyone else out there experiencing this issue with the 744? We can talk about systems theory between manufacturers all day long...rofl, but I'm trying to figure out what I'm doing wrong here after the queen update and reading the above sticky on this subject.Again, with the A/P, A/T, and LNav or hdg select engaged I'm not getting any automated speed control.

[MarkRey 16]

Jeff,My 1 2 3 are these and I never have VNAV trouble - assuming fmc fully configured:Arm a/t and vnav on the ground - engage toga for takeoff, fly manually up to about 1500 - 2000ft following f/d then engage a/p.orArm a/t and leave vnav off - engage toga for takeoff, fly manually to 1500 - 2000ft following f/d then engage a/p and vnav.I've never used v/s on takeoff - don't know if this is an issue?regards,Markhttp://www.precisionmanuals.com/images/forum/747400.jpgXPHomeSP2/FS9.1/3.2HT/1024mb/X700pro256

[Jeff Nielsen 1,386]

Thanks Mark,I've never tried arming VNav before leaving the ground. I usually have everything just about the way you do, except I don't use TO/GO. I have the A/T always armed prior to even taxiing out. I advance the throttles manually, lift off manually, the after about 500' AGL I engage the V/S to about 2000/min along with LNav while cleaning up the rest of the way so following the FD (It is on though) is not really an issue for me as I'm already in LNav and looking at the ND. Once I'm cleaned up I engage the VNav. I have the speed set to 250 KIAS for obvious reasons before engaging VNav.So I take it you do have speed automation then, correct?Thanks for the reply.

[michal 44]

>Again, with the A/P, A/T, and LNav or hdg select engaged I'm>not getting any automated speed control.None, even in such basic vertical mode as V/S? Michael J.http://www.precisionmanuals.com/images/forum/pmdg_744F.jpghttp://sales.hifisim.com/pub-download/asv6-banner-beta.jpg

[Jeff Nielsen 1,386]

Correct.

[MarkRey 16]

Yes I do - I like to let the fms handle power so all my derating and speed restriction is already set in the fmc. All that's left for me is to as I've said. Autothrust works by the book for me thereafter till t/d.I fly basically this bird just like the 767 and 777regards,Markhttp://www.precisionmanuals.com/images/forum/747400.jpgXPHomeSP2/FS9.1/3.2HT/1024mb/X700pro256

[Jeff Nielsen 1,386]

Ok, that's what I thought. Then I have to figure out what's happening with my bird all of the sudden then.Thanks guys.

[MarkRey 16]

but how could you? v/s, lnav or hdg sel have zero to do with automatic speed.Tell me this - if you have a/t armed, press the round white button below the speed window(forget it's name) so it 'opens' to current speed, then press SPD, does autothrottle engage then?regards,Markhttp://www.precisionmanuals.com/images/forum/747400.jpgXPHomeSP2/FS9.1/3.2HT/1024mb/X700pro256

[Jeff Nielsen 1,386]

Mark,I was just giving you the overall big picture. Lateral Navigation has nothing to do with speed automation.I think the button you're refering to though, is the speed intervention button which you can use in VNav mode if I'm not mistaken.In any case, I should have speed automation in any mode as long as the A/T and A/P's are engaged. That was my understanding.I might make a video for everyone to see.

[Guest D17S]

C, I'm looking at exploring the level of built-in safety that CAN exist. The Wright Flyer was not near as safe as a modern 747, but we can all agree Wilber did a great job. Talk about situational awareness! The old DC8s I deal with don't have ATs at all and they manage just fine. . . as did Charles Lindberg.You are exactly correct. The AP and the AT systems are separate systems on most aircraft with Gen 2.5 AFSs (for the sake of description) and therefore these systems HAVE to be dealt with separately. However, the MD11 -we will be getting from PMDG in a bit- is a Gen 3 airplane (again, for the sake of description) and has the AT and AP systems fully integrated. On that airplane, the AP/AT is treated as a single system. There's just one big ol' "red button" on the MCP called AutoFlight. My argument is this about that . . . it's a better, safer system design. The

[michal 44]

Forget about LNAV, or heading selection. Forget even about FMC - lets keep it simple. Tell us how you can't control speed using V/S mode (I picked this one for simplicity). Assume you are cruising at say FL310 and want to go up to FL350 using V/S. Tell us how you do it, step by step and why do you think A/T doesn't control your speed. Describe what your expectations are and what happens instead. Make sure your A/T switch is on.Michael J.http://www.precisionmanuals.com/images/forum/pmdg_744F.jpghttp://sales.hifisim.com/pub-download/asv6-banner-beta.jpg

[Jeff Nielsen 1,386]

Speed has nothing to do with V/S. I'm not sure how we got that confused.Plan and simlpy I just have no speed automation for some strange reason.I have no idea why the A/T's aren't working for me. I know this because when the A/T's are "on" I can move the throttles manually in their full range and watch the airspeed change.Edit: Maybe we can set up a MP flight and you can watch how I'm doing it?

[michal 44]

>Speed has nothing to do with V/S. It has, if you engage V/S you should be able to adjust both your V/S and aircraft speed. It is a nice environment (mode) at which to test A/T and the tradeoffs between aircraft speed and climb speed. Sure you can test it without V/S too. I only tried to help. Anyway, signing off.Michael J.http://www.precisionmanuals.com/images/forum/pmdg_744F.jpghttp://sales.hifisim.com/pub-download/asv6-banner-beta.jpg

[Guest D17S]

Oops, Sorry for stealing your thread . . . back to business.I tried it just the way you described. AT armed, but thrust manually set for TO. Hand fly to about 1000 feet and engage V/S. It captured my existing V/S. Then over to the MCP's AT buttons. First I tried "SPD" to get the AT engaged. No luck. Then I tried "THR." That got it. The Left FMA went to "THR REF." Then I was able to press the MCP's "SPD" button and "SPD" annunciated in the left FMA. During all this button pushing at TO power -- first manually set then "THR REF"erenced -- V/S was providing no speed control. I had accelerated way beyond the V2+10 I had set in the MCP's airspeed window for TO. Now with the AT engaged in SPD, thrust pulled back to capture my MCP airspeed. Nooooo! I was climbing through 2500 ft by then and I was all done V2'ing. So back to the MCP and dialed in 250 kts. Thrust ramped back up and away I went. . . right through my flap speed limit. I pulled up flaps and went in to the FMC and set climb power. But speed topped out at about 230. At V/S's ROC, all CLB thrust could do was 230. OK, now roll back V/S so I can get up to 250. Yea-ha! This is great fun and really keeps a pilot hoppin' . . . I've found something new to play with. But after a while, I was sure was eyeballin' that Vanv button. As a real world procedure, I think Vnav's still the best bet.If you want to set 250 in your MCP for TO, well, that's non-standard for a 744 (that's what we'll set in the MD11's MCP airspeed window for TO, though). In these Gen 2.5 AFSs, some version of V2 goes in the MCP airspeed window for TO. But a 250 knot setting would solve the slow down problem that occurs when the AT finally hooks up in "SPD with V/S mode engaged for pitch. However, this is all more for entertainment purposes. The use of V/S for an initial climb is not using the system to its best advantage. Using V/S can work, but if a pilot is going to use V/S, they really better have a firm grasp of all this theoretical systems nonsense. But just for fun, I found that the AT hooks up just fine in V/S. You WILL have to press either "THR" or "SPD" over on the left side of the MCP to get the AT initially engaged. You have to pay attention though. In V/S, you can engage the AT in either THR or SPD. "THR" will provide no speed control. If you engage "SPD" with V/S controlling pitch, you may not have direct control of speed with the MCPs airspeed knob. If thrust is already maxed out, dialing in a faster airspeed will do nothing unless you engage the CJS. All in all, it's a very work intensive, manual mode.Try using the AT for TO ("TOGA" in the left FMA) and arm Vnav. At 250 feet, press the AP button. The pitch will mode change from