Hi,

I am far from new to the NGX but trying to hand fly the SID's with only AT on more and more.

 

When I try to hand fly a SID with hight restrictions and also below 250 speed. I level off and the CoP has set flap up speed etc, but as I level off the speed just keeps going up till I over speed. No AP on ofc just AT.

 

I feel a n00b but I have to ask what am I doing wrong guys?

 

Thanks.

Hi. A screenshot of the mcp when you level off and the speed keeps increasing would help.

You can try a couple of things.

1. Make sure you select SPD on the mcp for the autothrottle

2. Make sure you do not have "ALWAYS" set in the "autothrottle override" option in the plane's setup on the FMS and are leaving the throttle levers above idle

3. Make sure the vertical mode selected is suitable for the use of autothrottle only (eg not VNAV, might be wrong here)

4. Try fly in full manual to understand better what should be happening and what actually happens and where it goes wrong?

Hope it helps

If you hand fly the aircraft there is absolutely no need for autothrottle.

Turn both, the AP and A/T off and hand fly the palne. Just keep practising, get to know the flight characteristics and you'll get better and will nail every single landing in the future.

 

Cheers

AT must be always used in conjunction with AP, if AP is off, turn the AT off. It will be not reliable and it will give you delayed reactions to your manouvers.

Hi,

I am far from new to the NGX but trying to hand fly the SID's with only AT on more and more.

 

When I try to hand fly a SID with hight restrictions and also below 250 speed. I level off and the CoP has set flap up speed etc, but as I level off the speed just keeps going up till I over speed. No AP on ofc just AT.

 

I feel a n00b but I have to ask what am I doing wrong guys?

 

Thanks.

I'm guessing you aren't selecting the height restriction on the MCP altitude window and a vertical Flight Director mode. Without this selected, if you manually level off the A/T may still remain in thrust mode and so you will continue to accelerate to overspeed. If you have the height restriction in the window and have a vertical mode selected for the FD, such as VNAV or FLCH, then as the altitude is acquired the A/T will change from thrust mode to speed mode and hold the IAS that is selected.

AT must be always used in conjunction with AP, if AP is off, turn the AT off. It will be not reliable and it will give you delayed reactions to your manouvers.

It isn't essential to switch A/T off with AP off. It can be convenient to keep A/T engaged. Some airline SOPs require it though. Typically for takeoff you will have A/T engaged in TOGA but no AP of course. What the OP is trying is not engaging AP subsequently. This isn't the same as flying with AP and A/T engaged, then disengaging AP and leaving A/T on.

Thanks Kevin, that sounds great will try that tonight. Thank you.

When you decide to disconnect the Autopilot there is no need also switch off the flight directors, all you need to do is fly to keep the two pink lines centred, use the MCP to set speed, altitude and flight mode as you normally would if the A/P was engaged, then you shouldn't have to worry about when to DECEL because when your chosen flight mode commands this it will be reflected on the FD on the PFD. This will also reflect the actions of the A/T provided you are following the FD

 

AT must be always used in conjunction with AP, if AP is off, turn the AT off. It will be not reliable and it will give you delayed reactions to your manouvers.

 

Not always true, in fact with certain approaches, especially short, tight visuals it might actually be beneficial to leave the A/T as not having to worry about moving the throttle and controlling speed frees up space in your mind to concentrate on turning final, lining up, establishing on the PAPI etc...

Not always true, in fact with certain approaches, especially short, tight visuals it might actually be beneficial to leave the A/T as not having to worry about moving the throttle and controlling speed frees up space in your mind to concentrate on turning final, lining up, establishing on the PAPI etc...

 

...provided your airlines SOP allows this, and you don't mind going against the suggestion of Boeing, sure. To me, part of staying ahead of the plane is setting the throttle (especially in a turbine) on your own, and adjusting as appropriate. You won't be able to get to the point of being able to manage all that on your own in a tight spot if you rely on the automagic all the time.

 

 

 

In any case, we're drifting from the initial issue. The OP has two choices:

1 - let the automagic handle the AT, but make sure it knows where it's leveling off (setting the alt on the MCP and using a mode that recognizes that)

2 - pull the AT off after departure so that he has control of the throttle to avoid the overspeed

Just came across this thread, and maybe someone can shed some light on this:

 

I've always been of the opinion - and that's what I've been doing for a long time now - that you arm the auto throttle prior to take-off, even if you're going to hand-fly up to, say, FL100. My A/T would stay on during all this time, with me just working the controls and following the flight director.

 

Is this not how it can be done?

 

Regards,

Oli

 

 

Oliver Branaschky

Just came across this thread, and maybe someone can shed some light on this:

 

I've always been of the opinion - and that's what I've been doing for a long time now - that you arm the auto throttle prior to take-off, even if you're going to hand-fly up to, say, FL100. My A/T would stay on during all this time, with me just working the controls and following the flight director.

 

Is this not how it can be done?

 

Regards,

Oli

 

 

Oliver Branaschky

Yes, that's how it's done. Leave it on until you're landing, if you like.

Thanks, really appreciate your answer :-)

 

 

Oliver Branaschky

...provided your airlines SOP allows this, and you don't mind going against the suggestion of Boeing, sure.

 

I have searched the FCTM and am yet to find this suggestion

 

PMDG-NGX-FCTM 5.77-5.78 Approach and Missed Approach (pp 254-255) No suggestion to the use of autothrottle

I have searched the FCTM and am yet to find this suggestion

 

PMDG-NGX-FCTM 5.77-5.78 Approach and Missed Approach (pp 254-255) No suggestion to the use of autothrottle

Check out the "AFDS Guidelines" section on Autothrottle Use.

Check out the "AFDS Guidelines" section on Autothrottle Use.

 

Well I stand corrected. Thankyou for pointing this out, it has given me an opportunity to learn something new.

 

However I still believe that in some circumstances that it may be beneficial to leave the autothrottle engaged whilst turning finals in a tight visual or VNAV instrument approach as it reduces workload , once visual, by all means disconnect the autothrottle.

The main problem is that the engine response is delayeddue to engine spoolup, if you are descending with AT engaged and at a costant speed and you starts to reduce pitch, the speed will drop, the AT will give power to counteract the speed drop, but, in the same moment you resume the previous pitch, or even more to stay with the FD bars, the engine is still spooling up to met the previous demand when the AT starts to reduce power and then, after another delay the engine spools down, it will FOR SURE overshoot the speed target.

If a pilot does the same he knows if it is a momentary movement, and will act not moving the throttle, or, if the manouver will take more time, he will anticipate thrust demanding at the same time he starts the manouver, well knowing that engine needs time to give you the required power or to remove power.

It is no more workload than other planes without AT that fly everyday