A Go-Around question

[teropa]

Hi,I have the Mike Ray book plus a real flight crew training manual for the 767.Still, after doing some missed approaches tonight in VATSIM for fun and training, one thing is left to haunt me. One "biggie".Ok, I know all the do's and dont's of a missed approach, and what I'm supposed to do in all phases. But, here's the scenario:I'm flying a manual ILS with F/Ds on, Autopilot AND A/T disengaged. In PIC when one disengages the A/T, the A/T switch goes to OFF, and not stay in ARM as IRL when disarming the A/T from throttles! Am I now supposed to REARM the A/T switch for a possible missed approach, or how is this done IRL ?Ok, I'm continuing the approach, and let's say (for convenience) that I have rearmed the A/T switch, but am still manually controlling thrust and of course the autopilot is still off. Then, I decide to execute a missed approach. I press G/A, say "going around, flaps 20", my f/o puts the gear up after I tell it (once pos. rate), and off we climb away.... or do we. Do I have to MANUALLY FIREWALL THE THROTTLES, because in PIC767 regardless of A/T switch position (ARM or OFF), I am not getting the engines to spool up to G/A thrust after pressing G/A EVEN when I do have the G/A mode armed (G/A appears on upper EICAS TMC limit) ???????The big question is this: How should I manage my thrust on manual go arounds ? I have thought that the real aircraft will provide G/A thrust IF:1. A/T is armed and G/A mode armed2. G/A switch is pushed in the throttles.Would someone please shed some light to this, or is my system malfunctioning ?? No need to explain the procedure in detail, because I have all the information about the big V's, this and thats about it already. Only, this puzzles me: a/t operation and thrust setting generally during a G/A.regardsTero

[Guest MB327]

Been there, done that!I will not attempt to provide the real world answer but will say that the "noise" in "my" throttle assembly (Suncom Thrustmaster) does not play well with the PIC autothrottle. If I am going around after switching off the AT, I never go back to AT control because of the high probability that the thrust setting will hunt back and forth between the EICAS TMC limit and the actual position of my hardware throttle handles. Once I switch off the AT on an approach and control the thrust manually, I stay in that mode regardless of any situation that develops. Only after stabilizing in level flight will I attempt to pull back the throttles and flip on the AT. But I watch it like a hawk for several seconds.

[Guest Ian_Riddell]

Just wondering if your MCP altitude was set higher than your current altitude, Tero? I can't find any reference to this in my 767 books, but it's a prerequisite for a 747-400 Go-Around.Flaps must be out OR G/S must be captured, also, but it sounds like you have at least one of these.Cheers.Ian.

[Guest anthonyj]

To answer the question simply when you press the go-around switch(es) with the autothrottle arm switch on the autothrottle will reengage and advance the thrust levers to try to achieve a specified rate of climb, up to the GA thrust limit. The aircraft must continue to be flown manually with reference to the FD, unless an autopilot is then engaged.If the autothrottle arm switch is off the thrust must be manually advanced.This is the real world situation. I hope that's what you are after.

[teropa]

Guys,Yes, I had the MAP ALT set for the go-around.Again, I had A/T in ARM and G/A mode was armed. After pressing G/A the FMA correctly annunciated "G/A G/A G/A", and it commanded go-around attitude. Problem is: The throttles would NOT advance!! I had to manually firewall them, and this is what is IMO a bit odd.Like Anthony said, with the A/T switch in arm, the A/T should've re-engaged and advanced the throttles. It didn't do that.I might have had some kind of A/T failure though, which I didn't check after landing. Will do some retesting today, I'll report back.Tero

[Maxthrust]

Hi,I think we have to press N1 after G/A in PIC. Hmm, somebody must make a wishlist for new 767?? I think A/T is a bit lazy in G/A's. It took too much time to achieve full G/A Thrust unless throttles manually firewalled. I was making a Autoland with A/T speed mode and tried to make a G/A just 50feet above the runway. Autopilot catch the G/A pitch very well and I selected flaps 20 but the Thrust was increasing too slow and speed was decreasing. Then I disengaged the A/T and pushed it to upper end but it was too late :-(May be I was wrong with my procedure;In autoland with A/T;First push G/A, Select flaps 20, Positive rate, gear up.

[teropa]

Hi,Answering to myself here, but this is also to Bozhan who has made the same discoveries as myself.Tried several scenarios.1. manual approach with A/T in ARM (but not engaged). "A/T inhibits manual throttle" NOT selected (ie. manual adjusting possible)approaching minimums, select G/A, flap20, rotate to 15ANU, posrate -> gear up.Result: A/T didn't do anything, nada. Just stayed in the setting I had left the thrust at.-> I'm using CH Pro Yoke, which produces "noise" in the system, and prevents for the autothrottles going into G/A thrust2. manual approach with A/T in ARM (again, not engaged). "A/T inhibits manual throttle" SELECTED (manual adjustments NOT possible).approaching minumums, select G/A, flap20, rotate to 15ANU, posrate -> gear up.Result: As I rotated firmly but smoothly to 15 degrees, A/T started to "catch up" on the procedure at about 10ANU, and after that VERY slowly increased thrust to abt. 96N1 (GA thrust on EICAS showed 105.1 limit), which produced the required 2000fpm climb but AT a speed of 130 KIAS at lowest!!! (Vref=131KIAS). After establishing on the climb, the A/T G/A mode did not transition to SPEED as it should (afaik), but stayed in the G/A UNTIL I selected FLCH at Acceleration ALT.conclusion: Three flaws in the A/T system during go around. Firstly, the A/T advances throttles to the required thrust dangerously slowly. Such behaviour would be totally unacceptable in the real aircraft. Secondly, why does it start to reduce to derated G/A thrust once established on 2000fpm climb, when speed indicated is as low as VREF (a tad above FLAP20 buffet speed). Thirdly, it does not transition to SPD once established on climb.Some of my findings may be contradicted with something else, but as of now, I'm always making my goarounds by firewalling the throttles.3. automatic approach all the way to minimums. Both AP and A/T engaged. "A/T inhibits manual throttle" SELECTED.Result: same behaviour as above. The aircraft DID perform a go-around, but the speed fell dangerously low... I would not have wanted to be onboard the bird during a go-around this time. Also, if one is to NOT use "A/T inhibits manual throttle", ie. if one wants to be able to assist A/T at times (as IRL is often needed), then going around with A/T armed and letting the system take over is definitely out of question.Let me add, that IRL of course the thrust levers are also manually thrown into firewall during a G/A, but the servos should be moving them TOO!Comments anyone ?Terops. I didn't remember to test the G/A by selecting N1 at at the same time as G/A! In theory, N1 should immediately advance the throttles to G/A thrust (provided G/A annunciated in EICAS), which is effectively the same thing that the mere G/A switch SHOULD do. Bozhan, care to try that ??

[Guest Claude troncy]

Bonjour,I noticed that the engine spool up to G/A thrust only if vertical speed is negative at the moment you press the G/A switch.That could be a problem on a non precision approach or if there are some turbulences.Claude Troncy

[teropa]

Claude,Interesting observation.Didn't pay attention to that, but I'm sure that the VSI was negative (ie. descending) everytime I pressed G/A.Also, I tried hitting the N1/EPR as well after pressing G/A, and that does indeed work as I suspected, and G/A thrust is added rapidly.A small step from reality, but at least that enables for safer Go-arounds when flying a coupled approach.Tero

[Guest MB327]

Tero,It is impossible for me, and many others I suspect, to directly compare results when it comes to the AT, GA mode, and N1 for that matter. One of the primary contrubutors to the problem is throttle noise. " "A/T inhibits manual throttle" SELECTED (manual adjustments NOT possible). " That statement does not really apply to all hardware setups. I can change that setting back and forth all day and it has no effect on anything. It is a noise issue in my situation with an analog throttle assembly plugged into a game port. But there are many cases of the same problem with USB throttle controls.But having said all of that, your observations of a slowly responding GA mode are valid in my opinion.Mike

[teropa]

Mike,Well... I'm using CH Pro Yoke. BUT... to make this "issue" even more clear, I did disconnect the joystick (CTRL+K) in one scenario (manual approach, A/T was flipped back to ARM), to see if disconnection the hardware would make any difference. It didn't.Sloowww....Tero