10 hours ago, Donstim said:

What is the source of this information?  The length of the takeoff roll depends not only on the takeoff thrust being used, but also on the takeoff speeds. The takeoff speeds vary with the runway length, pressure altitude, OAT, and airplane weight. There is no way that the takeoff roll takes the same amount of time for every takeoff, though use of Flex may lessen the differences some.

Numerous training programs… an unusually light aircraft at max thrust results in a high acceleration rate with Rotation speed achieved way sooner than normal. This results in time compression which reduces the opportunity to evaluate and deal with failures after TOGA. Additionally there is a higher propensity for flap speed exceedence and Level Off busts.

No take off roll is exactly the same, however, one that follows the “usual” timeline is better at keeping all crew members on the same page of sheet music.

Thank-you and the rest of the FBW Team for your work- it is most appreciated.

C

On 4/4/2022 at 3:04 AM, Donstim said:

What is the source of this information?  The length of the takeoff roll depends not only on the takeoff thrust being used, but also on the takeoff speeds. The takeoff speeds vary with the runway length, pressure altitude, OAT, and airplane weight. There is no way that the takeoff roll takes the same amount of time for every takeoff, though use of Flex may lessen the differences some.

 

The FBW A32NX does simulate Flex now.

It is simulated for engine thrust output for the A32NX.

Although we are working on it, it will be some time before this happens.

Re #3 first, with respect to MSFS I've often wondered this myself. MSFS pilots usually don't have to worry about failures during the takeoff that would jeopardize safety and necessitate the use of a correct V1, nor more than a minimum VR and V2. I doubt that the typical MSFS pilot would even know what V1 is for. But I understand the desire for the feeling of realism even if not all the realism aspects are there.

For #2, these calculations are required to be done for every takeoff in order to show compliance with takeoff performance regulations. Basically, transport category airplanes must be able to safely accelerate to the engine failure speed and then continue the takeoff with one-engine-inoperative, or reject a takeoff with the first action to stop the airplane taken at V1 and be able to stop the airplane within the available accelerate-stop distance. The airplane must also meet certain minimum climb requirements and be able to clear all obstacles under the takeoff path.

For #1, the calculations may either be done by the pilots using an EFB, or by a dispatch office using either an EFB or desktop computer.

 

.. or failing that, runway analysis tables prepared by the manufacturer (these days quite rare)