On the B744, derate and assumed temperature settings used are entirely a matter of airline policy. I believe that BA do not allow their B744 pilots to use either method.

No, not at all. The calculations are then for normal takeoff power to reach Vr and V2 appropriate to the runway length and meteorological conditions.

 

I should add that my experience is entirely for the B744.

 

I am very confused you just said that BA don't use de-rates or assumed temps meaning that all take off's are at MAX power.

 

On the B744, derate and assumed temperature settings used are entirely a matter of airline policy. I believe that BA do not allow their B744 pilots to use either method.

 

Again based on what? I'll bet everything I have that BA use de-rates and assumed temps on the 744's. De-rates and assumed temps are for prolonging engine life, saving fuel and overall efficiency. Why wouldn't the largest operator of the 747 want to do this?

All that I can say is from my beliefs. I am not a member of BAVirtual so cannot confirm.

 

But if both items are not airline specific, why does TOPCAT explicitly support these as options for each aircraft?

But if both items are not airline specific, why does TOPCAT explicitly support these as options for each aircraft?

 

Remember that TOPCAT isn't used in the RW. The only situation that I could think of where D-TO's and assumed temps wouldn't be used would be for aircraft at MTOW, an aircraft that's reasonably heavy taking off on a short runway or for taking off on a runway that is surrounded by very high terrain.

This is an appropriate place to post my 777th post!

 

BA do not use assumed temps or derates and all takeoffs are with flaps 20, I believe.

No, not at all. The calculations are then for normal takeoff power to reach Vr and V2 appropriate to the runway length and meteorological conditions.

Similar to the others, I am having difficulty understanding your statement. Do you mean:

1. British Airways always uses full takeoff thrust, but uses derated-thrust takeoff speeds for full-thrust takeoffs, or

2. British Airways actually sometimes uses derated takeoff thrust, but uses full-thrust takeoff speeds for derated-thrust takeoffs?

 

Logic tends to indicate that neither of these statements seems practical or realistic. Operating a fleet of 55 B747s instead of B777s must already be somewhat inefficient. On top of that, constantly using full takeoff thrust, as others have mentioned, can shorten engine life span. In the second statement, interchanging takeoff speeds in such a fashion may result in dangerously inaccurate or inappropriate figures.

 

Are either of my interpretations of your statement correct? If not, could you please clarify?

EFB does all the calculations after loadsheet is received for optimal flap settings, assumed temps / derated TO and the speeds. They are entered by the pilot into CDU and cross checked for those calculated by FMC.

 

2. British Airways actually sometimes uses derated takeoff thrust, but uses full-thrust takeoff speeds for derated-thrust takeoffs?

 

 

 

I believe this is what is mcdonar saying, however I hardly believe it to be the case. Well, maybe except for "sometimes"...

I have said only one thing and I shall repeat it:

 

[bold]I believe[/bold] that BA policy for the B744 is not to use derated thrust or assumed temperature for takeoff.

 

I do not know about any other aircraft types used by BA.

 

We shall have to await confirmation from a BAV pilot to know whether I am right.

 

Now, PAX!

I have said only one thing and I shall repeat it:

 

[bold]I believe[/bold] that BA policy for the B744 is not to use derated thrust or assumed temperature for takeoff.

 

From the BAV-747-FCOM p36- FMS Preparation:

 

"Enter Assumed Temperature into the SEL field, check EPR matches TOPCAT/UTOPIA figure and reduce/increase the assumed temperature entered until the SEL field until FMS EPR equals TOPCAT/UTOPIA figure. Check TO or D-TO with assumed temperature is displayed on the Upper EICAS. Select CLB or CLB-1 as appropriate"

From the BAV-747-FCOM p36- FMS Preparation:

 

"Enter Assumed Temperature into the SEL field, check EPR matches TOPCAT/UTOPIA figure and reduce/increase the assumed temperature entered until the SEL field until FMS EPR equals TOPCAT/UTOPIA figure. Check TO or D-TO with assumed temperature is displayed on the Upper EICAS. Select CLB or CLB-1 as appropriate"

This is a BA Virtual manual, not necessarily applicable to BA. However I'd be very surprised if BA didn't use derates and assumed temperatures for its 747s.

All BA takeoffs are not commonly flaps 20 for the 777. You can tell just by looking at videos that they use flaps 5 a lot by the small amount of flaps deployed

Posted this in a PM:

 

Not all aircraft have EFB

 

During setup we, the crew, will request performance information through the 'comm' section of the ECL/ACARS. We will enter the current ATIS and the desparture runway and receive back a performance sheet optimised for the runway, weather conditions, load and climb out performance.

 

In the Perf section of the FMC we will enter the aircraft reserve fuel level, the trip cost index (0 for the climb then 'normally' 100 for the cruise) and the ZFW. The FMC will then calculate the gross weight. This procedure is only done after fuelling is complete.

 

We then conduct a 'thrust setting' procedure on the FMC whereby we will enter any 'D' rate required on the performance printout. This will result in wither the selection of full climb power or one of two reduced climb powers (used to prolong engine life/cycles) of CLB1 or CLB2.

 

On completion of this we enter the performace page of the FMC. The flap selection from the performace sheet will be entered in the top left and the MACTOW (%) will be entered on line 5R. The FMC will then use all given data to calculate it's own V speeds (Vr and V2, it doesn't calculate V1 as it will never anticipate a split). We then check that the calculated V speeds are within 3 knots of the speeds achieved from the performance sheet printout. If they differ then an error has been inputted somewhere in the performance loading.

 

Generally they are within 1 knot.

 

As such, in a simulator, if you use flap 5 on a runway like Heathrow, 50 degrees for the 'D' rate and enter the weights correctly then the V speeds should be accurate.

The only places I can think that may require flap 20 on departure on the BA network are Cardiff (At high gross weights) and Sydney off runway 07/25. Flap 5 is the norm on the -200 and some -300ER departures with Flap 15 for the rest and the odd -200 departure.

 

BA's 777s are setup so that the TO 1 and TO 2 thrust ratings are not available, only leaving TO (D-TO with assumed Temp) available for selection along with CLB, CLB1 and CLB2. TO B (Bump) is only available on G-VIIN.

BA's 777s are setup so that the TO 1 and TO 2 thrust ratings are not available, only leaving TO (D-TO with assumed Temp) available for selection along with CLB, CLB1 and CLB2. TO B (Bump) is only available on G-VIIN.

This would make more sense than having only a maximum thrust takeoff option. Perhaps this is the reason for some of the confusion in this thread regarding the engine customizations of British Airways.

The only places I can think that may require flap 20 on departure on the BA network are Cardiff (At high gross weights) and Sydney off runway 07/25. Flap 5 is the norm on the -200 and some -300ER departures with Flap 15 for the rest and the odd -200 departure.

 

BA's 777s are setup so that the TO 1 and TO 2 thrust ratings are not available, only leaving TO (D-TO with assumed Temp) available for selection along with CLB, CLB1 and CLB2. TO B (Bump) is only available on G-VIIN.

 

 

TO-B was always restricted to Denver, hence it was known as Denver Bump.

 

Jo Burg, Denver and occasionally Honk Kong have been known to demand flap 20 at high weights.

 

To summarise, the FMC calculates speeds based upon entered parameters. The ACARS performance sheet is cross check to ensure the figures are 'close' (+/- 3 knots) and the ACARS performance figures are used. If no ACARS is available then the figures are manually calculated from the take off performance manual.

 

Enjoy.

Flap 5 is the norm on the -200 and some -300ER departures with Flap 15 for the rest and the odd -200 departure.

 

The 300ER generally needs TO-B with Flaps 20 at Heathrow :rolleyes: :lol:

(Joke!)