Changing carriers on OW RTW
 

I previously posted a question regarding earning AA miles when flying BA/QF on a OW RTW ticket. Someone very cleverly noted that AA will start codesharing some of the BA flights so that 100% AA miles could be earned (say) from SIN-LHR.

Does anyone have an idea about how easy it would be to switch from a BA to an AA flight number? The flights are filling up, so I certainly don't want to wait for the codeshares to come along. I am thinking of booking on BA, and (since changes to date/time don't cost anything) switching to an AA flight number later. If this won't work, then I'd rather book on QF now instead of BA.

As you say, you can certainly make changes to flight times (and carriers) at will, but availability of space is another question. I note for example that ITN will show a CX flight with A availability while the same flight with an AA flight number will show F but no A. I have no idea if this actually means anything since in most cases the same miles end up in your AA account.

You can definitely change carrier as long as the routing stays the same - e.g. I have changed from QF to BA and vice cersa LHR-MEL.

Thanks guys that is useful info

To the best of my knowledge you have always been able to earn AA miles SIN - LHR on BA. The problem has only been on transatlantic BA flights.

Earning the 100% (or more) though will depend on the class of ONE.

After the end of this month on BA, you only earn 25% of actual miles for SIN-LHR. On QF it would be 70% of actual miles [assuming travel in Y]. Consequently, you're better off booking on QF from the perspective of accumulating AA miles.

If AA put a codeshare on the BA flight, then you're better off flying the BA flight under the AA flight number, and earning 100% miles.

This much is well-established.

The point of the original post was to determine how easy it would be to book a seat on the BA flight and then switch (potentially the same seat) to an AA flight number when the codeshare is implemented.

Has anything changed regarding AA miles accumulation on BA flights in D or A? I thought that stayed the same, except that now transatlantic (except to U.S.) has been added to the elegibility list, with the normal multipliers and status multipliers.

That's all true, the original poster appears to be contemplating a MONE.

You might run into 2 snags: some airlines insist on reissue of ticket (and collecting the change fee) even though it is not needed (AA does this, while BA and QF usually accept the flight coupon). The second snag is that codeshare inventory is separate and not transferable (also seat assignments usually are not transferable). Typically AA buys very few seats on codeshares and doesn't sell many at a discount; so you are quite likely to find plenty of BA inventory and zero AA inventory. Your existing seat cannot just be transferred, and often the codeshare partner is allocated all the crummy seats on the plane.