Hmm, see this is still rumbling on. For what it's worth my answer to the original question (for EU-Ops, non ETOPS) is that IF an en-route alternate is required because you need to reduce your contingency fuel below 5% of trip due to performance/payload problems OR you are using the 3% ERA reduction procedure (they are different things for different situations) then it must be "adequate" and permit a landing to be made at ETA +/- 1 hour using the standard alternate planning minima.
For a twin on a non-ETOPS flight you must also remain within 1 hours SE flying time of an adequate aerodrome, the definition of which does not include any weather criteria.
Last edited by Max Angle; 21st Jul 2009 at 18:53.