Originally Posted by
flight01
Hi, does anyone understands the logic of why you could dispatch to a runway that is contaminated as long as you have 2 alternates planned. But you are not allowed to apply this logic to a runway that is dry/wet.
(both under most favorable, no wind conditions)
Hi,
as already mentioned above the idea is if you dispatch to a destination with a dry or wet runway You must be able to satisfy the dispatch landing criteria on the most favorable runway. Example: summer time, you fly at night to a greek island on a fully loaded A321/B738. Runway 36/18. Calculations done for the most favorable runway with no winds: good to go. Imagine only Runway 36 has an IAP and 18 nothing, no circling or visual allowed. Current winds are likely to assign you 36 with max tailwind. Dispatch performances are red. You can dispatch legally with a suitable alternate as prescribed in the AMC as with no wind you would be good to go. Of course you can reduce the weights and so on to fit on Rwy 36, but we are talking about legality rather than operational effects. By the time you get there your IFLD might give you thumbs up. Same story if the runway is wet.
Now, if your landing dispatch results are red even on the most favorable runway with no winds, you have to do something about it, i.e. reduce payload. It's mainly common sense, you can't dispatch somewhere where the calculations done prior to the flight are a no-no.
On a contaminated runway chances are that the runway will be cleared and/or better RWYCC by the time you get there. So you are good to go even if you don't fit in the most favorable runway but you need more safety nets, i.e. 2 alternates.