How to use a/t during short final

[Nigge 20]

hi,

i have had this problem a couple of times so im pretty sure iam doing something wrong...

during my final approach i turn off the speed mode on the mcp but the the auto throttle on arm

but the problem that I have had is that just before touchdown the aircraft decides it doesnt want to land at all and spools up the engines which results in a missed approach... really annoying...

what migt i be doing wrong? my thought is that i move te throttles to idle before the pfd tells me to, can that cause this behaviour?

/Niklas

[Meese 5]

Disengage A/T.

 

You oughta try to fly by the old stick n rudder, it gives for a much more fun experience than A/P all the way in.

[Nigge 20]

I am not actually not using the A/T, when i disengage the speed mode then the throttles are manual, the auto throttle is just armed to be prepared for a go around situation...

I belive I have read that that is the "correct procedure" (absolutely not sure about this one so please feel free to correct me:-) )

[pride545 30]

How are you disengaging the "speed" mode?

[Nigge 20]

By pressing the speed button so that i neither have n1, speed nor VNAV activated...

[Xenowings 9]

If you did not press the VNAV button it will presumably still be using FMC speeds, so you must disengage the A/T switch, and also unless your intention is to perform an auto land i would disengage the A/P completely

[Levkov 8]

I think the disengagemet keys are SHIFT+R, I am not sure

[Jazz 1,047]

I am not actually not using the A/T, when i disengage the speed mode then the throttles are manual, the auto throttle is just armed to be prepared for a go around situation...

I belive I have read that that is the "correct procedure" (absolutely not sure about this one so please feel free to correct me:-) )

 

Disengage the A/T either by the switch or by the A/T disconnect button on the throttles themselves. Your problem I suspect will go away.

[Nigge 20]

Both Vnav and speed are disengaged... And of course, the problem doesnt exist if i disarm the auto throttle... But I thought the idea was to keep the A/T armed in cause of go arounds...

[Jazz 1,047]

Personally I tend to turn everything off and land manually but what your describing sounds odd and should not be happening. I am trying to think what may be causing it but off the top of my head I can't come up with anything. I am sure someone will show up with the answer though.

[Nigge 20]

I do the same most of the times,but I recon seeing somewhere (not sure if it was in this forum or somewhere else) that the correct procedure is to leave the A/T in armed mode during approach in case of a sudden go around situation...

 

So thats why I have tried this a couple of times... And more than once this has happened...

The only thing that I can "think of that i might have done wrong" is that i lowered the throttles to idle before the PFD told me to...

But I was at lowest only about 2 or 3 kts below my VREF speed so there was no risk of stalling...

[Chrjs 61]

I do the same most of the times,but I recon seeing somewhere (not sure if it was in this forum or somewhere else) that the correct procedure is to leave the A/T in armed mode during approach in case of a sudden go around situation...

 

So thats why I have tried this a couple of times... And more than once this has happened...

The only thing that I can "think of that i might have done wrong" is that i lowered the throttles to idle before the PFD told me to...

But I was at lowest only about 2 or 3 kts below my VREF speed so there was no risk of stalling...

 

Please correct me if im wrong (Im not real pilot) but as far as i know there is no automatic go-around for the 737 (at least with only one or none AP engaged) - pressing GA will in this case disconnect both the AP and AT. So if you initiate a GA you have to manually control both the controls AND the throttle.

In your case pressing "Speed" does NOT disconnect the AT, but engages the Speed mode. For landing you have to disarm the AT on the MCP or (better) press teh "Soft" AT disarm switch on the throttle itself (twice to mute the AT disconnect warning).

 

Regards

[Nigge 20]

Please correct me if im wrong (Im not real pilot) but as far as i know there is no automatic go-around for the 737 (at least with only one or none AP engaged) - pressing GA will in this case disconnect both the AP and AT. So if you initiate a GA you have to manually control both the controls AND the throttle.

In your case pressing "Speed" does NOT disconnect the AT, but engages the Speed mode. For landing you have to disarm the AT on the MCP or (better) press teh "Soft" AT disarm switch on the throttle itself (twice to mute the AT disconnect warning).

 

Regards

'

 

Just to clearify myself... During the approach I was in speed mode (green light underneath the speed button), then on finals i press the button to disconnect the speed mode...

And I got (at least it seems that way) full control of the throttles... untill like 10 feet above the ground, when A/T kicks in again...

 

This it not really a problem, It can easily be avoided by disarming the A/T then this isnt happening... but as I wrote earlier...

I think I have read that the correct procedure for this is to have A/T armed...

But it seems like I have misread this so then there is absolutely no problem;)

 

/Niklas

[kevinh 409]

In real life you wouldn't disarm the A/T that way, and you are probably only disengaging the speed mode. Far better to assign a key to the A/T disconnect switch via the CDU options. That way you can disengage the A/T correctly and leave the switch in ARM in case of a go around.

[xxJohnxx 21]

In real life you wouldn't disarm the A/T that way, and you are probably only disengaging the speed mode. Far better to assign a key to the A/T disconnect switch via the CDU options. That way you can disengage the A/T correctly and leave the switch in ARM in case of a go around.

 

If you dissconnect the A/T via the throttle, the switch moves, powered by a solonoid, from the ARM position to OFF, so in case of a go arround, you would have to move it up to ARM again, however you can also manually set the desired thrust, can't you? At least you are the pilot. :wink: