Originally Posted by
Jonty
My FCOM gives a Vref of +25kts for slats locked at <1. That’s still a flap 3 landing.
Flysmart doesn’t add the Vref for separate failures, it takes the worst and you use that.
The problem here is that they’re not separate failures in terms of performance. If you have slats and flaps at 0 you don’t take the worst of a slats OR a flaps failure, you have to combine them. Flysmart will consider combinations of slats/flaps failures and will give the correct delta Vref, eg +45 for slats<1 and flaps<1, but doesn’t apply the same logic to a G+Y LO
PR and a slats failure.
This is identical to what the QRH does. It has performance for combined slats/flaps failures but does not have performance for other combinations. Presumably this is because the various flap/slat combinations are normally just different products of the one failure.
When the OP checks the QRH table for slats and flaps < 1 they are doing exactly what they should do in Flysmart. Put the complete wing surface position in as a separate failure, not just the slats, so that Flysmart can give the appropriate Vapp corrections and the appropriate performance penalties for stopping on the runway.