I apologize if this question has already been posted...

I absolutely love the B747 Queen of the Skies V2, but always have an issue climbing out due to very low N1 setting with auto throttle engaged. It appears that the auto throttle t is almost cut in half during climbout, making the plane stall. I almost always have to kill the auto throttle, and manually manage the throttles to get the Queen accelerating and climbing. 

I have all the latest patches installed.

Does anyone have any advice as to what I am doing wrong.

Thanks for the feedback!

Gary

Hi,

_ What is the N1 setting you have during the climb (any derate selected, CLB, CLB1, CLB2)?

_ What is the thrust mode displayed on the FMA? 

_ And what is the position of your thrust levers (both in the plane and on your hardware)?

A reason for not having the correct thrust setting if the THR REF is displayed is that your hardware is interfering with the sim.

If you advance manually your throttle quadrant to 70% (or another setting), hit TOGA and leave your hardware there, chances are that depending on the option selected in the PMDG setting>simulation (via the CDU, on hold only, always...) for your hardware, then any signal sent by your hardware will bring the thrust back to the one corresponding to the position of your hardware.

You may either advance manually your throttle quadrant to match the TO thrust setting after hitting TOGA, or set the option to on hold mode only for your hardware in the PMDG settings to prevent any signal from your hardware from being picked up by the sim during the climb.

Make sure your outside temp isn‘t unrealistically high. I have read about an issue with low throttles due to an issue with the weather program that created  20C at 20000ft... this would force the autothrottle to such a low power setting.( just like assuming high temperatures to derate your power for takeoff)

Hi Gary,

Like you, I Iove this aircraft but unfortunately you have not provided any data about the airfield runway, the weather conditions or the configuration of the aircraft you are having these problems with. Are you using the default fuel figure? If you are then try reducing the fuel load to 40,000kgs/88,000lbs first and see if this improves the climb performance using all of your existing settings.

Many factors can affect the climb performance of the B744, so without all of the relevant performance information it is almost impossible to give you a definitive answer. The B744 doesn't climb as well as a twin engine aircraft, especially at max takeoff weight when the climb performance and acceleration during flap retraction can be quite demanding. However, the most likely cause of your problem with the auto throttle controlling the engines and poor climb performance is when something has not been programmed correctly into the FMC.and/or AP/FD. Romain Roux has already given you some good suggestions to try, but I believe you should also have a good look at your aircraft configuration (especially the fuel load and takeoff weight) AND your programming of the FMC. If you look at the THRUST LIM page in the FMC you will see two fixed Derate Thrust settings on the left for TO1 and TO2. You should NEVER change or use one of these for take off because they are not normally used in everyday operation.

Using the RR B744 as an example, I suggest you have a try with some realistic settings for a takeoff out of Boston on RWY 04R (dry). If you have AS2016 or similar then set the WX to W/V 340/20; OAT +54F; QNH 30.10. Use a ZFW of 215.0Kgs/475.0lbs; Fuel load 50.0Kgs/110.0lbs (with 15.0/33.0 as Reserve), Stab CofG 21 and APU off with all Packs ON. This will give you a fairly light (i.e. training) takeoff weight of 265.0Kgs/580lbs. The Take-off criteria for this particular B744 variant is normally based on the use of Flap 20 and a reduced thrust setting, which is obtained by using an assumed temperature calculation. In this example the takeoff calculation produces an Assumed Temperature to use in the THRUST LIM page of +70C (and a VMCG of 136kts). When you insert this Temperature into the FMC watch what happens to the Reduced Thrust (CLB) selection on the right side. Incidentally, most of the time it will automatically default to CLB 1 and this is what I normally use in the QOTS, but you can try a different CLB setting later on if you wish with other Assumed Temperatures. I often use 56C if I don't have any data for a given runway. You can even experiment with this same data at Washington Dulles if you want to and increase the fuel loads too! Provided the departure runway is >9.000ft I will often insert a route into the FMC; use an assumed temp of + 56C and then adjust the fuel load to give me approx 12.0Kgs/27.0lbs planned on landing. So far I have always managed to get airborne before the end of the runway and I haven't had to go and visit my virtual Hub Manager for a ticking off for stalling it either!

Happy Flying and Happy New Year.
Bertie Goddard

17 hours ago, berts said:

If you look at the THRUST LIM page in the FMC you will see two fixed Derate Thrust settings on the left for TO1 and TO2. You should NEVER change or use one of these for take off because they are not normally used in everyday operation.

Bertie, would you mind expanding on this? Why is it not used, and what is the correct method for derating a takeoff in the B744? Flex only?

3 hours ago, MattS said:

Bertie, would you mind expanding on this? Why is it not used, and what is the correct method for derating a takeoff in the B744? Flex only?

I picked up on this during beta testing from one familiar with BAW operations.  I believe (I'm not an expert like Simon or Bertie) it depends on operator. I've played with this and when heavy will usually take off with D-TO and TOGA pitch modes and then bug up the speed for flap retraction and then selecting VNAV and CLB-1 or -2 as appropriate once clean and established in the climb.

5 hours ago, MattS said:

Bertie, would you mind expanding on this? Why is it not used, and what is the correct method for derating a takeoff in the B744? Flex only?

As Dan says, this is very much operator dependant.

As far as BA are concerned, as far as I know all normal takeoffs are assumed temperature only (full TO with an assumed temperature reduction): TO1 or TO2 may - very rarely - be used (without an assumed temperature) on contaminated runways where the derate may actually give you a higher TOPL via a reduced Vmcg/Vmca. TO2 is also used for three-engine ferries (again, due to the reduced Vmca/Vmcg giving better controllability and reduced speeds).

Other operators may vary! 

So would a combination of assumed temperature reduction and a fixed derate ever be used? Or is it pretty much one or the other?

Not at the Big Airline as TO1 and TO2 are only approved for operations from contaminated or degraded braking action runways where no assumed temperature reduction is permitted.

I can't speak for other operators! 

1 hour ago, skelsey said:

Big Airline

And who would that be? 

blaustern

4 hours ago, Bluestar said:

And who would that be? 

I assume British Airways.

17 hours ago, skelsey said:

Not at the Big Airline as TO1 and TO2 are only approved for operations from contaminated or degraded braking action runways where no assumed temperature reduction is permitted.

I can't speak for other operators! 

Thanks Simon. You're always a big help and good contributor to the forum. Cheers!

Really operator specific. Martinair Cargo uses a combination of fixed de-rate and assumed temperature on the 747. Normal ops.

On 12/29/2017 at 6:16 PM, MattS said:

Bertie, would you mind expanding on this? Why is it not used, and what is the correct method for derating a takeoff in the B744? Flex only?

Sorry for not replying sooner - hols, family priorities etc!! . 

Simon has already given a good explanation about the use of these fixed derates - which I presume he also uses in BA. The actual amount of derate applied if TO1 (i.e. contaminated/VMCG limited runways) or TO2 (i.e three engine ferries) is being used can also vary depending on the specific engine model and rating (anything from say 10% for TO1 to 25% for TO2). Contaminated runway calculations can be complicated, but it is important to note if you want to try a sim takeoff on a contaminated runway then normal reduced thrust is not used.

Three engine ferry operations, especially the takeoff, are in a completely different ball park!.  They are non-revenue flights and the flight crews have to be specially trained to carry them out

Bertie