I did got it straight and it's been done. My colleague bought a AA codeshare Y ticket with Cathay, used miles to upgrade himself to J.

Sorry, but it's done.

I am glad that my thread has sparked a lively discussion and debate. Further contributions would be greatly appreciated as well.

Just to clarify a few things from the comments above:

1. Since I live in YOW, it is 2 transit points anyway: with CX it would be YOW-YYZ-HKG-BKK and with NH, it would be YOW-ORD-NRT-BKK. However, it is much faster and easier to go with CX since I avoid the American customs thing, as well as the unpredictable nature of short flight cancellations into and out of Chicago during bad weather.

2. I do not take AC because I had too many bad experiences with their service in J. I used to be a SuperElite and after feeling badly treated, I switched. I am much happier now.

3. I am primarily interestd in flying between Canada and Asia, on a carrier with top notch service (therefore preferably an Asian carrier), and if possible in F. Therefore, the AA programme would give me free CX flights, but I can't use any of their upgrade features.

4. From what you all describe, a central 'power' feature of being a diamond is that you get on flights whenever you want seats, even last minute. This is indeed an excellent feature suited to last minute business travellers, particuarly premium passengers who need to jet across for an important closing... I am not one of those customers. I do fly a lot (150-200K per year) but almost all of it is planned at least a month in advance, and often 2 months. I seldom change the date last minute and my local professional commitments do not permit too many changes. Therefore, this feature of the diamond membership is not useful to me.

So unless there are other features I don't know about (quite possible), the benefit of CX to me would be shorter transit times and avoidance of US customs, and the benefit of NH would be much more generous upgrades.

For me this is a really tough call. The transpac F experience on Asian carriers is really nice, even if you have done it many times before. However, as we all know, long flights with transits can be exhausting, no matter how you do it and so shorter times can make a big difference.

I still don't know...

FF

and the miles here is indeed "AAdv miles" ? what kind of Y ticket - full fare or discount, which sub-class ? and when was this ?

if this were indeed true, it's definitely one of the biggest surprises none of us here knew about before...and would make me credit more of my future miles to AAdv instead of MPO/AM...

To be exact, there is no seat guarantee for F, and seat guarantee for J/Y requires 24 hours notice. In your case, if you need to do an upgrade on a CX flight, a DM status will be helpful as CX may release a redemption seat to you early on. However, the burn-earn ratio is so bad that you may get enough miles for an upgrade about once every five round trips on J.

Well, if your Cathay route is frequently overbooked then the chance of you getting upgraded is very high for DM, however, if you're already booking J then the chance of J to F is not that high, although it does happen if J is full as well so they need to push J to F to make room for Y to J.

@FlyingFish: I looked at the numbers. Assuming starting from zero status on AA, after four RTs YYZ-HKG-BKK on CX, you will get to AAdv EXP elite status and will have 135k AA miles, enough for one F award ticket, along with 20 domestic upgrade stickers, and 8 systemwide upgrades. Each additional RT as an EXP will get just under 40k miles. Yes, all those upgrades are only good on AA flights and your priority for op-ups on CX, even as a top-tier EXP, will be lower than if you were a DM, but they aren't zero either.

Definitely, shorter overall flight times and avoiding unnecessary border crossings is a good thing though!

So how do you explain: from this page on the AA site: http://www.aa.com/pubcontent/en_US/A...p#travelawards

My suspicion is that your colleague used AsiaMiles, which can be used to upgrade AA flights booked in YBH.

Ugh....this is like pounding on rocks. You have clearly confused AA miles and Asia Miles, and now we have lots of incorrect information on this site to boot. You just cannot upgrade with AA miles. Period. I am not basing this on reading FT - I'm basing it on a colleague who has a hoard of AA miles (quite fewer Asia Miles), boasted to our whole office how much better off he was with his AA miles when using upgrades, until he had to eat his own words HKG-LAX when he showed up at the airport assuming he could upgrade and was told to pay or fork over ASIA MILES. Not AA miles. With AA miles you can buy AWARD tix, and with AA codeshares you can buy a high-fare subclass and upgrade using ASIA MILES (NOT AA MILES!!!!), but what you insist is correct just plain isn't.

hmm I thought OP has specifically asked for DMs? From time to time I see faulty comments being made from FTers here some of the names seem to be on the list over and over again...