737NG A/T & F/D GA Mode
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737NG A/T & F/D GA Mode
With the A/T Arm switch at ARM, the A/T go–around mode is armed:
• when descending below 2000 feet RA
• when above 2000 feet RA with flaps not up or G/S captured
• with or without the AFDS engaged.
On my last flight, I was maintaing 2300RA with Flaps 1. The TMD was annunciation CRZ.
1) Shouldn't it be annunciating G/A?
2) If I just maintain 1900RA with Flaps up, will the TMD be G/A?
If both A/Ps are not engaged, a manual F/D only go–around is available under the following conditions:
• inflight below 2000 feet RA
• inflight above 2000 feet RA with flaps not up or G/S captured
3) why does it say descending for A/T & inflight for F/D Go-Around?
• when descending below 2000 feet RA
• when above 2000 feet RA with flaps not up or G/S captured
• with or without the AFDS engaged.
On my last flight, I was maintaing 2300RA with Flaps 1. The TMD was annunciation CRZ.
1) Shouldn't it be annunciating G/A?
2) If I just maintain 1900RA with Flaps up, will the TMD be G/A?
If both A/Ps are not engaged, a manual F/D only go–around is available under the following conditions:
• inflight below 2000 feet RA
• inflight above 2000 feet RA with flaps not up or G/S captured
3) why does it say descending for A/T & inflight for F/D Go-Around?
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Its talking about when TOGA is available. What you see on the TMA is just N1 limits. If you press TOGA it will then change to G/A.
Regarding the descending part - I believe its on the assumption your doing an Autoland and would be descending, where as in manual flight you could be straight and level for a bit.
Regarding the descending part - I believe its on the assumption your doing an Autoland and would be descending, where as in manual flight you could be straight and level for a bit.
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Thanks for the reply 900ER.
G/A annunciates on the TMD only after Glide Scope Capture or at about 1800 RA for CDFA Approach.
However with flaps extended above 2000 feet RA, there is no A/T GA available. Why?
G/A annunciates on the TMD only after Glide Scope Capture or at about 1800 RA for CDFA Approach.
However with flaps extended above 2000 feet RA, there is no A/T GA available. Why?
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Hi 737 NG, I am sure once you have met the arming criteria for the TOGA bottoms and A/T is engaged, when pressing them you will have the A/T in GA.
As a sim instructor I realized that the sim doesn't always 100% reproduce aircraft behavior. This is due to different software or config differences. Just try it on a nice calm day in the A/C wit no traffic and push TOGA. Just remember to disengage the A/T immediately and recycle the F/D bars to open the speed window. Your bug will move slightly upwards too, so reset the target speed.
As a sim instructor I realized that the sim doesn't always 100% reproduce aircraft behavior. This is due to different software or config differences. Just try it on a nice calm day in the A/C wit no traffic and push TOGA. Just remember to disengage the A/T immediately and recycle the F/D bars to open the speed window. Your bug will move slightly upwards too, so reset the target speed.
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With the amount of questions the OP asks on this forum, I Personally wouldn't let him loose on a bike, let alone punching in TOGA unnecessarily and expecting him to recover from it.
No offence.
No offence.
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Repulo, 737900ER, I would be one of those, with whom you may leave your aircraft safely.
The questions, I ask on these forums, are because the system behavior is slightly different from what is mentioned in the FCOM. Specially with, systems related to auto flight. And I want to understand my a/c better.
Simple example, none of you could answer when does G/A annunciate on TMD. The A/T will never go into Go-Around mode, unless G/A annunciates on the TMD, irrespective of your RADIO ALTITUDE.
Please try this in your simulator or a/c.
Anyways, I appreciate your attempts to answer my doubts. No offense
The questions, I ask on these forums, are because the system behavior is slightly different from what is mentioned in the FCOM. Specially with, systems related to auto flight. And I want to understand my a/c better.
Simple example, none of you could answer when does G/A annunciate on TMD. The A/T will never go into Go-Around mode, unless G/A annunciates on the TMD, irrespective of your RADIO ALTITUDE.
Please try this in your simulator or a/c.
Anyways, I appreciate your attempts to answer my doubts. No offense
With N1 selection in AUTO, the FMC switches to GA from CRZ on the TMD only when TOGA has been pushed. FCOM 2 11.31.32 is the reference. As regards "when descending below 2000ft RA", I think you are having an English comprehension issue. My reading is that the mode becomes active as the aircraft descends below 2000RA, not if the aircraft is in a descent below 2000RA.
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As per FCOM (FMC)
Below 2000 feet radio altitude, the FMC transitions to go-around logic from approach logic when any of the following events occur:
• pushing either TO/GA switch while in a descent
• executing a direct-to waypoint in the missed approach (other than the missed approach point)
As per FCOM (A/T)
With the A/T Arm switch at ARM, the A/T go–around mode is armed: when descending below 2000 feet RA .
My question is related to the A/T GA mode. If I maintain 1500RA in clean configuration, the TMD should be G/A. But it remains in CRZ.
Below 2000 feet radio altitude, the FMC transitions to go-around logic from approach logic when any of the following events occur:
• pushing either TO/GA switch while in a descent
• executing a direct-to waypoint in the missed approach (other than the missed approach point)
As per FCOM (A/T)
With the A/T Arm switch at ARM, the A/T go–around mode is armed: when descending below 2000 feet RA .
My question is related to the A/T GA mode. If I maintain 1500RA in clean configuration, the TMD should be G/A. But it remains in CRZ.
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I am going to spend the next three days in the SIM and will have a glance at the mentioned situation. I'll let you know, whereas I still think that my description earlier is correct.
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Hi everbody
B737NG_PILOT, lets see if I can help with this matter.
The trouble with this system, is that it does get a little bit confusing., I think it helps to break up the involved systems... On one hand we have the A/T as part of the AFDS. The A/T will enter a thrust or speed mode.
On the other hand however, the A/T primarily uses LIMITS calculated by the FMC. (although, A/T can in fact receive other limits, in a degraded mode from the EEC, these are CLB, CRZ and REDUCED go around thrust, aka GA.
A/T G/A mode is ALWAYS (ILS and NON-ILS) armed in one of the 3 scenarios that you have correctly quoted. However, even though it is armed, it is not necessarily displayed. (The same occurs with the A/P go-around mode….. it arms, but it is not displayed!!).
Regarding the A/T LIMITS (provided by the FMC), the TMD will show G/A whenever a G/S is captured, obviously for an ILS approach.
On other types of approaches (VANV, IAN…) G/A will show on the TMD whenever the FMC transitions to a G/A. This will happen if the crew:
1. Does a "direct to" a point in the G/A
2. The system sequences a point in the G/A
3. TOGA is pushed
4. A climb is made at least at 600 FPM, whilst retracting flaps towards 15 (N) or 1 (N-1)
SO I hope these inputs have helped you.
Remember:
1. FMA shows A/T mode
2. TMD shows FMC thrust limit mode (A/T will never command more than this value)
3. G/A A/T MODE is only displayed when G/S is captured for an ILS approach
4. G/A A/T MODE is displayed when the FMC sequences to a go around mode (as seen above) for a non ILS approach.
5. TMD shows GA when an ILS G/S is captured
6. TMD shows GA when a non ILS approach sequences to a G/A (not before)
7. For a first push, A/T FMA mode shows GA
8. For a second push, A/T FMA mode shows N1.
* Regarding points 7 and 8, remember that the TMD will always show GA until a CLB mode is engaged.
Cheers!
B737NG_PILOT, lets see if I can help with this matter.
The trouble with this system, is that it does get a little bit confusing., I think it helps to break up the involved systems... On one hand we have the A/T as part of the AFDS. The A/T will enter a thrust or speed mode.
On the other hand however, the A/T primarily uses LIMITS calculated by the FMC. (although, A/T can in fact receive other limits, in a degraded mode from the EEC, these are CLB, CRZ and REDUCED go around thrust, aka GA.
A/T G/A mode is ALWAYS (ILS and NON-ILS) armed in one of the 3 scenarios that you have correctly quoted. However, even though it is armed, it is not necessarily displayed. (The same occurs with the A/P go-around mode….. it arms, but it is not displayed!!).
Regarding the A/T LIMITS (provided by the FMC), the TMD will show G/A whenever a G/S is captured, obviously for an ILS approach.
On other types of approaches (VANV, IAN…) G/A will show on the TMD whenever the FMC transitions to a G/A. This will happen if the crew:
1. Does a "direct to" a point in the G/A
2. The system sequences a point in the G/A
3. TOGA is pushed
4. A climb is made at least at 600 FPM, whilst retracting flaps towards 15 (N) or 1 (N-1)
SO I hope these inputs have helped you.
Remember:
1. FMA shows A/T mode
2. TMD shows FMC thrust limit mode (A/T will never command more than this value)
3. G/A A/T MODE is only displayed when G/S is captured for an ILS approach
4. G/A A/T MODE is displayed when the FMC sequences to a go around mode (as seen above) for a non ILS approach.
5. TMD shows GA when an ILS G/S is captured
6. TMD shows GA when a non ILS approach sequences to a G/A (not before)
7. For a first push, A/T FMA mode shows GA
8. For a second push, A/T FMA mode shows N1.
* Regarding points 7 and 8, remember that the TMD will always show GA until a CLB mode is engaged.
Cheers!
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Having said this, I know need help form somebody!!!
Also regarding the TMD….
According to BOEING, the A/T Go-around mode is terminated whenever:
1. A new pitch mode is SELECTED
2. ALT ACQ engages.
Additionally, BOEING tells us that if an A/P is engaged in CMD, pitch will engage in LVL CHG, and roll will engage in HDG SEL…
This last point greatly confuses me…. If I engage an A/P in CMD; does this mean that A/T GA mode will be terminated???? Or not…? (One thing is to SELECT a new pitch mode, and another thing is for the A/P to engage in command, and LVL CHG mode too will ENGAGE).
Not sure if my question is "understandable" Hope so!!!
Thanks
Also regarding the TMD….
According to BOEING, the A/T Go-around mode is terminated whenever:
1. A new pitch mode is SELECTED
2. ALT ACQ engages.
Additionally, BOEING tells us that if an A/P is engaged in CMD, pitch will engage in LVL CHG, and roll will engage in HDG SEL…
This last point greatly confuses me…. If I engage an A/P in CMD; does this mean that A/T GA mode will be terminated???? Or not…? (One thing is to SELECT a new pitch mode, and another thing is for the A/P to engage in command, and LVL CHG mode too will ENGAGE).
Not sure if my question is "understandable" Hope so!!!
Thanks
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Sorry for the delay, couldn't try it in the SIM, had other things to do.
But I had a chance to try it in the A/C on a visual approach to Fuerte Ventura.
Condition:
- A/P engaged in V/s
- descending to 1600ft
- TMA in CRZ
- TOGA pressed at 1600 ft, TMA went into GA, A/P disengaged with the known
FMA annunciation.
So every thing went as already anticipated earlier, A/T has the same TOGA arming criteria like the A/P.
But I had a chance to try it in the A/C on a visual approach to Fuerte Ventura.
Condition:
- A/P engaged in V/s
- descending to 1600ft
- TMA in CRZ
- TOGA pressed at 1600 ft, TMA went into GA, A/P disengaged with the known
FMA annunciation.
So every thing went as already anticipated earlier, A/T has the same TOGA arming criteria like the A/P.
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Alberto, if lvl change is engaged, its N1 limit is CLB. With some 737 even on T/O the TMA will go to CLB below thrust reduction alt if level change is pressed. It depends on the soft ware. We have one old A/C that has a different config since it is leased in that does that. Hope that helps.
There are thousands of pilots out there who have insufficient tech knowledge and don't ask any questions. The OP consistently seeks more knowledge. We should never discourage that. Good on you mate, keep it up.
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Repulo, thank you for you answer.
However i´m not convinced……. According to FCOM, during a go around, A/T GA mode ends when LVL CHG is SELECTED…..
If I happen to engage the A/P during said go around, LVL CHG will ENGAGE (also HDG SEL, unless LNAV was already engaged)…
You see, the trouble that i´m having is with the wording. If if engage an A/P, then LVL CHG will ENGAGE, and I mean ENGAGE, and not SELECT, I understand that it is not the same thing…. Does the system think like I do, or maybe not…?
So, if I engage an AP, perhaps TMD would still display GA rather than CLB (because I have NOT selected a pitch mode, instead, this mode has been engaged automatically) until a new pith mode is SELECTED, or ALT ACQ??? For me, this point is not clear at all in the FCOM..
Do you see were i´m going?
Sorry if i´m confusing you guys, and sorry for "beating around the bush", but I just like to have things crystal clear!
Cheers
However i´m not convinced……. According to FCOM, during a go around, A/T GA mode ends when LVL CHG is SELECTED…..
If I happen to engage the A/P during said go around, LVL CHG will ENGAGE (also HDG SEL, unless LNAV was already engaged)…
You see, the trouble that i´m having is with the wording. If if engage an A/P, then LVL CHG will ENGAGE, and I mean ENGAGE, and not SELECT, I understand that it is not the same thing…. Does the system think like I do, or maybe not…?
So, if I engage an AP, perhaps TMD would still display GA rather than CLB (because I have NOT selected a pitch mode, instead, this mode has been engaged automatically) until a new pith mode is SELECTED, or ALT ACQ??? For me, this point is not clear at all in the FCOM..
Do you see were i´m going?
Sorry if i´m confusing you guys, and sorry for "beating around the bush", but I just like to have things crystal clear!
Cheers