albertofdz

19th Aug 2012, 16:40

Good afternoon chaps;

I have been studying the new In Flight Performance section of the QRH, in particular I have paid special attention to the VAPP and landing distances calculations with failures.

At a first glance, I thought these calculations would be easier, however i'm having touble understanding certain calculations.

Let me set an example:

Imagine we suffer a dual hydraulic failure, G+B for instance, lets say that a dual leak has occured after takeoff performed using CONF 2.

According to the FCOM APPR PROC, flaps 2 will be used, and because s=2, APPR SPD will be VLS+10. This is where I get confused.

According to the new section added in the back of the FCTM, (LANDING PERFORMANCE - VAPP DETERMINATION WITH FAILURES) after using the matrix to asses the rwy condition, a VAPP and landing distance is extracted from the appropriate table. This section also states that certain procedures require the VLS to be incremented, this appears to be such a case.

However, the new IFL charts include delta VREF and landing distances for this very same failure.

The question is, what should I choose? Must I wait for the flaps to be extended and add 10kts to the VLS? Perhaps I should use the speeds extracted from the charts?

This speed calculation part is quite frankly getting on my nerves!

Some help would be ever so appreciated.

Happy landings to all.

Albertofdz

I have been studying the new In Flight Performance section of the QRH, in particular I have paid special attention to the VAPP and landing distances calculations with failures.

At a first glance, I thought these calculations would be easier, however i'm having touble understanding certain calculations.

Let me set an example:

Imagine we suffer a dual hydraulic failure, G+B for instance, lets say that a dual leak has occured after takeoff performed using CONF 2.

According to the FCOM APPR PROC, flaps 2 will be used, and because s=2, APPR SPD will be VLS+10. This is where I get confused.

According to the new section added in the back of the FCTM, (LANDING PERFORMANCE - VAPP DETERMINATION WITH FAILURES) after using the matrix to asses the rwy condition, a VAPP and landing distance is extracted from the appropriate table. This section also states that certain procedures require the VLS to be incremented, this appears to be such a case.

However, the new IFL charts include delta VREF and landing distances for this very same failure.

The question is, what should I choose? Must I wait for the flaps to be extended and add 10kts to the VLS? Perhaps I should use the speeds extracted from the charts?

This speed calculation part is quite frankly getting on my nerves!

Some help would be ever so appreciated.

Happy landings to all.

Albertofdz