I still struggle with this, did not the regulator simply list the combinations to cover all bases?
Hope I can express myself well:
Discussion on the article is relevant only when the article would apply - i.e. force the dispatcher to load additional fuel. Tankering disregarded, that is never desired. Consequently, when presenting the pilot with diversion strategies, the expert would have needed to say:
- this is your EO diversion and alternate route A-B-C, requiring additional regulatory fuel of XXX.
- this is your EO + DEPRESS diversion alternate route J-K-L, requiring additional fuel of ZZZ but that being less than XXX,
= we're uplifting XXX, the higher of the two, apart from the standard route requirement.
Bollocks. He'd say - in case of a simple EO you will fly the diversion alternate route J-K-L and profile which is designed for the EO+DEPRESS case actually, so that's all simplified for you. The additional fuel requirement is ZZZ, no more required than that.
If someone is suggesting there's a scenario when a certain route good for EO+DX cannot be executed under simple EO - without the help of DX -, let's hear it.
Perhaps an argument can be made that under a simple EO which is far less of an emergency compared to EO+DX, another alternate is preferred that may be further out. Well, no one is going to load greater amount of mandatory fuel for that possibility, plan A is to reach the destination AEO and carry payload instead. Not to mention the obligation to land at the closest (terms of time) adequate airport following a loss of one.
n.b. the posters so far seem to disregard drift down speed and ceilings as opposed to EO LRC ceiling and schedules in their comparisons. Not sure if that is relevant.
There is a theoretical piece missing in that puzzle, not mentioned previously, which I'll keep in a closed hand for a moment awaiting your feedback.