Dustypfd interesting you bring this up...
Your way of thinking is correct, but the figures are a bit of.
Lets work on an example using the QRH for the A332-RR at 160T with calm winds:
The "correct Airbus way" is;
1/ From the QRH 2,40, Abnormal/Emerg config. Vref=Vls Full=128 or you can just see what the MCDU gives you as Vls Conf Full...should be the same.
2/ Add 5kts for the engine failure (2,42), 128+5= 133
3/ Select Conf 3 (MCDU/PERF) and enter 133 on the Vapp (MCDU/PERF)
If you check VLS Conf3 in the books (or in the MCDU, after having selected Conf3) @160T, you'll find 130. So in this case you'll fly Vls+3 and not Vls or Vls+5.
The way idg describes it, is a quicker way, but will give you a Vapp Conf3 of 135. 2 kts faster, and with the usual 5kts add on for using autothrust. The 5kts min above Vls when using ATHR is only for normal ops...
What is strange about the "correct airbus" procedure is that you'll fly 2kts or so slower (closer to Vls) with one engine out than coming in with both engines and doing a Conf3 landing, 133 iso 135. I know, only 2kts....
brgds:
