well spotted BOAC playing the words is the name of the game. here is the link
http://www.nats-uk.ead-it.com/aip/cu...9_P_045_en.pdf Practise suggests to have it. Not entirely sure what exactly you"re trying to say but I'll try it again:
alternate aerodrome can be skipped in both cases planning prior dispatch and re-planning in flight as both of them are considered as planning provided the conditions described before are met 2 RWYs less than 6 hours etc.
Once you got airborne or NO re-planning EU OPS 1.375 (b) is applicable
The flight must be conducted so that the expected usable fuel remaining on arrival at the destination aerodrome is not less than:
(a) the required alternate fuel plus final reserve fuel, or (b) the final reserve fuel if no alternate aerodrome is required.
However, if, as a result of an in-flight fuel check, the expected usable fuel remaining on arrival at the destination aerodrome is less than:
(a) the required alternate fuel plus final reserve fuel, the commander must take into account the traffic and the operational conditions prevailing at the destination aerodrome, at the destination alternate aerodrome and at any other adequate aerodrome, in deciding whether to proceed to the destination aerodrome or to divert so as to perform a safe landing with not less than final reserve fuel;
(b) the final reserve fuel if no alternate aerodrome is required, the commander must take appropriate action and proceed to an adequate aerodrome so as to perform a safe landing with not less than final reserve fuel.
The commander shall declare an emergency when calculated usable fuel on landing, at the nearest adequate aerodrome where a safe landing can be performed, is less than final reserve fuel.
That doesn't mean airlines can't impose additional restrictions mentioned by you like weather etc. I guess re-planning could be used in case the NEW destination is farther out than the originally planned one. Sometimes it's safer to land CAT III on the major one rather than to try your luck at the secondary with marginal CAT I. It's getting more interesting if both your destination and alternate are single RWY only. Isn't that why we sign route and aerodrome competency paper sheet?
Cheers
