IFF on MEL Dispatched Aircraft

[eca]

I have question about Actual Landing Distance (ALD) on MEL dispatched Aircraft.

My A320 was dispacthed with SEC3 inoperative. From MMEL 2.27 P8 said that Landing distance is increased by 5%. Therefore, my actual landing distance should be (ALD from 4.03)x 1.05.

But if I've got any Inflight Following Failure (IFF) such as an Anti-skid failed. Airbus recommends to calculate
ALD (MEL+IFF) = ALD from 4.03 x MMEL penalty (1.05) x Coef Anti-skid (1.75). It is not considered as a multiple failure! Is that sound?

Back to normal aircraft without MEL, if both failures occur inflight,
ALD (IFFs)= ALD from 4.03 x Coef SEC3 (1.25) x Coef Anti-skid(1.75)

what make the difference of landing distance? MEL SEC3 proc requires switch off SEC3 PB and pull out CB which is the same as that of SEC3 inops inflight? :confused:

[TyroPicard]

Don't have access to a MEL, not sure if this is correct but my experience with Airbus manuals and their logic would indicate:

You don't use the failure factor because you have not had an in-flight failure. You have despatched with SEC 3 INOP which is a different situation, and is therefore treated differently.

And also as an aside:
The 5% MEL correction is at the planning stage, and I reckon it should be on RLD which is approximately 1.65 times ALD.

[Alton77]

Thanks TyroPicard for your sharing.

In case of SEC3 inop, MEL Landing distance penalty increase by 5%. Yes, you have to check that RLD < LDA so that the a/c can be dispatched. Once inflight , how to calculate the ALD? Isn't it the ALD from 4.03 x 1.05 from MEL?

For SEC3 MEL items, you deactivate SEC3 by push it off and pull CB out. you lost spoiler surface 1&2, your landing is 5% more.

For SEC3 Fail inflight, you switch off SEC3 .. no CB out.. you lost spoiler 1&2, you landing is 25% more!!!

Don't know if there are more inop items affected from SEC3 inflight than that of SEC3 MEL.. that's the point. :confused:

[martuus]

so interesting item here, I do agree with tyropicard MEL use in planing state, it concerning RLD. But not clear when some following failure occur in flight, which correction should be used? I will use more margin for myself even it conservative.