The flight director is great when you are following it. The  PF was ignoring the commands. If you look at Boeing and Airbus SOP you will see that flight directors should be off when hand flying in most cases to ensure the A/T, A/THR reverts to SPEED. 

Hi, Marco,

 

Since you are named for the Roman Stoic philosopher (and emperor) Marcus Aurelius, you should not indulge in such frivolous activities.  Instead you should be a good Stoic and get down to the serious business of ... making videos for flight simulator!

 

Sorry, couldn't resist.

 

Mike

Cool Mike...and be sure that flying is better than soccer and I hope to do something at least to deserve a name like The Stoic Marcus Aurelius !

 

I'm right now indulging in editing the video as promissed.

 

Great.

 

Marco.

Hi Guys ...

 

Here is a short video as I've promissed....LPPT to LPMA only take-off and Landing. Here you can see clearly what I've been said

 

By-the-wayLanding was done without Autobrake (there is a small issue in this version ..but it works anyway ) nor spoilers.... the reason to not use both of them was to test Roll-Out charactheristics (the Reverse needs some refinements )...The Bird is Awesome ! Congratulations to PMDG Development Team and Beta Testers of course!

 

There is another video that I can show : Taxi to Parking ( Outstanding Aerosoft AES job ! )until secure procedures with a " Dessert " at final...The AI traffic landing at same Threshold...by the way 05.

 

Hi Mike....

 

Now are 08:45 local time 11:45 UTC....The Brasil X Chile soccer match wil be at 16:00 UTC. Just kidding. !..... my fellow simmer and Hopefully a friend. 

 

 

Warmly,

 

Marco Aurélio

Considering the release product we currently have models the FLCH correctly.

 

Then yes! it will be fixed in the service pack because it is fixed already in the release version. The changes should be as follows:

1: none

 

yay!

Hi my fellow simmer I'd like to invite you to seat at my right side ........

 

May be some day even in Real Life !

 

Best of all.....

Hi Guys ...

 

Here is a short video as I've promissed....LPPT to LPMA only take-off and Landing. Here you can see clearly what I've been said

 

I am not sure what we are seeing that we should not see.

 

As pointed out before, it is normal and correct that the AT mode changes from HOLD to THR REF in 400ft.

Even if Vnav is not armed as far as I know.

 

But the whole thing is more complicated as we think I guess.

 

I mean when you program the FMC you put in (or leave default) values for Thrust reduction and Acceleration right?

Are those Vnav functions?

or not?

And what about the THR REF function in 400ft, is that a Vnav function?

Or has it nothing to do with Vnav?

 

Vnav is actually just an AFDS pitch mode.

Either you follow the Vnav FD pitch mode, or the AP does it for you.

But Vnav is not an Auto throttle mode.

But AT and Vnav work as a team.

Just like in a Cessna engine RPM and pitch can both influence the same thing (speed and vertical speed).

 

So even though YOU do not arm Vnav for take off, the AT still reactivates at 400ft.

The only reason the AT is in HOLD mode to begin with during take off is so you can abort the take off or add thrust (in case of windshear for example) without the AT screwing your inputs up.

So why would the AT not reactivate in THR REF mode again?

What would be the purpose of an AT staying in HOLD mode longer, passed 400ft?

 

The FMC programmed acceleration altitude is a Vnav pitch instruction again.

It tells the AFDS Vnav mode to reduce pitch so the airplane accelerates.

 

But the FMC programmed acceleration height is actally an instruction to the AT system.

To reduce the thrust target from take off (or reduced take off) to climb thrust.

So whether or not you have armed Vnav.....will not matter.

The AT reduces to CLB thrust and Vnav Pitch mode keeps pitching to maintain the target speed.

Often, thrust reduction and acceleration are at the same height. So it may look like both functions are happening due to a Vnav command.

But they are two seperate commands. One to Vnav and one to the AT.

Just like in 400ft.....THR REF is an AT command, not a Vnav command and thus being in TOGA or VNAV has nothing to do with it.

 

But you know what, I have never done a real world take off with Vnav not being armed!

 

And I dont know why anybody would do such a thing.

 

Vnav gives FD commands that help you automatically.

Such as :

- Initially V2 +15 to 25. This speed is important in case you loose an engine because the whole performance calculation the pilots EFB makes before every take off (obstacle clearance after take off) is based on you flying this speed!

Fly something else or dont clean up as calculated and you could find yourself hitting an obstacle.

Even if you keep full thrust (single engine) but dont clean up at the Vnav commanded single engine acceleration speed!

(many people think it is better not to clean up single engine for obstacle clearance.....but that is not correct. Keep flaps at 5 all the way to 5000ft and you will have significantly more drag the whole time. The result is that you might not be abke to clear an obstacle that is further away)

- Vnav gives clean up/acceleration FD commands engine failure speed automatically.

- It prevents you from busting intermediate SID altitudes.

- It prevents you from overspeeding (flap placard speeds)

 

You dont use all that?

You go TOGA all the way to......?.....cruise FL?

Great...Great.....

 

And ?

I am not sure what we are seeing that we should not see.

 

As pointed out before, it is normal and correct that the AT mode changes from HOLD to THR REF in 400ft.

Even if Vnav is not armed as far as I know.

 

But the whole thing is more complicated as we think I guess.

 

I mean when you program the FMC you put in (or leave default) values for Thrust reduction and Acceleration right?

Are those Vnav functions?

or not?

And what about the THR REF function in 400ft, is that a Vnav function?

Or has it nothing to do with Vnav?

 

Vnav is actually just an AFDS pitch mode.

Either you follow the Vnav FD pitch mode, or the AP does it for you.

But Vnav is not an Auto throttle mode.

But AT and Vnav work as a team.

Just like in a Cessna engine RPM and pitch can both influence the same thing (speed and vertical speed).

 

So even though YOU do not arm Vnav for take off, the AT still reactivates at 400ft.

The only reason the AT is in HOLD mode to begin with during take off is so you can abort the take off or add thrust (in case of windshear for example) without the AT screwing your inputs up.

So why would the AT not reactivate in THR REF mode again?

What would be the purpose of an AT staying in HOLD mode longer, passed 400ft?

 

The FMC programmed acceleration altitude is a Vnav pitch instruction again.

It tells the AFDS Vnav mode to reduce pitch so the airplane accelerates.

 

But the FMC programmed acceleration height is actally an instruction to the AT system.

To reduce the thrust target from take off (or reduced take off) to climb thrust.

So whether or not you have armed Vnav.....will not matter.

The AT reduces to CLB thrust and Vnav Pitch mode keeps pitching to maintain the target speed.

Often, thrust reduction and acceleration are at the same height. So it may look like both functions are happening due to a Vnav command.

But they are two seperate commands. One to Vnav and one to the AT.

Just like in 400ft.....THR REF is an AT command, not a Vnav command and thus being in TOGA or VNAV has nothing to do with it.

 

But you know what, I have never done a real world take off with Vnav not being armed!

 

And I dont know why anybody would do such a thing.

 

Vnav gives FD commands that help you automatically.

Such as :

- Initially V2 +15 to 25. This speed is important in case you loose an engine because the whole performance calculation the pilots EFB makes before every take off (obstacle clearance after take off) is based on you flying this speed!

Fly something else or dont clean up as calculated and you could find yourself hitting an obstacle.

Even if you keep full thrust (single engine) but dont clean up at the Vnav commanded single engine acceleration speed!

(many people think it is better not to clean up single engine for obstacle clearance.....but that is not correct. Keep flaps at 5 all the way to 5000ft and you will have significantly more drag the whole time. The result is that you might not be abke to clear an obstacle that is further away)

- Vnav gives clean up/acceleration FD commands engine failure speed automatically.

- It prevents you from busting intermediate SID altitudes.

- It prevents you from overspeeding (flap placard speeds)

 

You dont use all that?

You go TOGA all the way to......?.....cruise FL?

I'm try to show something different...I'd like to use Hold Mode for more time.....and by the way as you might know TO/GA can cancel any time .......It is not the question.

 

But you have posted a huge and whealthy comment...thanks so much ...I'd like to say that you are a Stoic Simmer ! Sincerely....Thanks so much again.

 

Best of all.

 

Marco Aurélio

Marco,

 

As Kyle stated, if you press TO/GA a second time after accelerating through 50 knots, THR REF should not activate.

If you don't press TO/GA a second time, it will activate at 400ft.

 

 

Vnav gives FD commands that help you automatically.

 

Hi, Rob,

 

What guidance does the FD give on takeoff if VNAV is not armed and the Autopilot is off?  Inquiring minds want to  know.

 

 

Thanks,

Mike

Marco,

 

As Kyle stated, if you press TO/GA a second time after accelerating through 50 knots, THR REF should not activate.

If you don't press TO/GA a second time, it will activate at 400ft.

Please read page 326 of the FCOM Volume 2. 

 

Thanks,

 

MX.

Well, if you substitute the "50 knots" in my previous comment for "80 knots", it still counts, if I read it correctly.

Also, I have a feeling you are concentrating on "at 400 feet", on page 4.20.11 of FCOMv2.

As far as I can seem the first sentence and the second sentence there are not actually related. Whether VNAV is armed or not, THR REF will engage at 400 feet.

Marco,

As Kyle stated, if you press TO/GA a second time after accelerating through 50 knots, THR REF should not activate.

If you don't press TO/GA a second time, it will activate at 400ft.

That is not correct.

THR REF allways engages during take off.

 

- First TOGA push: THR REF engages. (if armed, Lnav and Vnav remain armed)

 

By the way and just as additional info, THR REF does not mean maximum thrust is set. All that means is that thrust is set to the target that was calculated for the take off (target is visible above the N1 box during take off, actaul thrust setting is in the box). This can be maximum thrust, but can also be reduced thrust.

 

- Second TOGA push (while still on the ground): no change to AT mode, but Lnav and Vnav are no longer armed. (the idea here is that you have a performance problem (maybe windshear) so you just want to go straight ahead rather than turning and following Lnav)

 

- Second push (while airborne after lift off): Again you probably have a performance problem if you did this, so you get TOGA for both Pitch and Roll mode. (so Lnav and Vnav are disarmed, or even disengaged and TOGA is engaged instead). THR REF in this case DOES go to maximum thrust. So even though the AT announcement is the same as before (THR REF), the reduced thrust is deleted and maximum T.O. thrust limit is set.

 

 

See also FCOMv2 page 4.10.19

You're right. I have just read both FCTM and FCOM again (well, not fully, just the concerned chapters), and I don't know where I got my previous understanding from.

Thanks for giving me the incentive to go back and read it again. ;-)

Hi, Rob,

 

What guidance does the FD give on takeoff if VNAV is not armed and the Autopilot is off?  Inquiring minds want to  know.

 

 

Thanks,

Mike

All you will have then is TOGA TOGA.

So TOGA for both roll and pitch.

 

Right after lift off:

Lateral:

This means the FD will guide you straight out.

Your actual flight track is actually determained at lift off and then this becomes your target Track. So normally, pretty much rwy track guidance, unless you were drifting all over the runway due to improper handling of an engine failure or crosswind condition.

 

Vertical:

And the FD will also guide you up to a pitch altitude that maintains the speed close to what you had set in the speed window before take off (This speed is called V2).

Close, because after liftoff the system first determains if all engines are still working or not. And then it checks at what speed you are currently flying.

Then it resets the speed in the window to a value between V2 and V2+25kt. No more.

 

For details, see the page that Thomas refered to (4.20.11 of FCOMv2.)

 

 

Upon reaching the altitude that was set in the altitude window before take off, the airplane will level off.

So you then get TOGA (stays engaged laterally unless you change it) and ALT.

But you do not get acceleration (for flap retraction) in 1000ft (for example).

And you will never get Lnav guidance unless selected manually.

 

AP engaged or FD only does not matter. They both do the same thing.

You're right. I have just read both FCTM and FCOM again (well, not fully, just the concerned chapters), and I don't know where I got my previous understanding from.

Thanks for giving me the incentive to go back and read it again. ;-)

No problem and welcome.

 

To be honest, the manuals are written in a way that one could easily misinterpret things.

 

Has happend to me a lot too, and the only way you find out is in discussions like these.