I cannot get a clear answer on this from AA RTW - they have given two contradictory answers:

On a RTW First Class ticket any sectors where First or Business are not offered should be booked into Y Class, not L or M - this change was made quite some time ago by all the airlines. It ensures full bonus miles and Q pts.

However, what AA can't agree on is into which class extra segments should be booked, e.g. in the US, if the ticket originates in, say, CAI, on top of the maximum of six US segments, one is allowed to book two additional economy segments at $150 each. As one is adding segments to a First Class ticket I would have expected these to also be booked into Y Class - one AA rep said "yes", one said "no".

Has anyone had experience of this, please?

Purchase of extra segments are in the same class or lower. If you buy down, then the inventory is that of the class purchased. In this case, I would say L since that is the inventory for economy. Remember that you are buying a class of service independent of the original fare basis. Note that L class gets 1.0 qpts in AA, so you are not forfeiting much.

I've purhcased additional coach segments in NA and they have all been booked into L. It doesn't matter if I was on AONEx or DONEx fares.

The reason why you could book into Y was because you paid for the higher class of service in those cases. I think if you were to pay for additional segments in A or D, then was downgraded because of equipment changes, you should be able to book into Y as you actually paid for A or D. Make sense?

If the additional segments are on another airline, e.g. EI, L Class earns no miles & no Qpts. Also Y Class has the advantage that, in the event that they overbook the flight which on LAX-SAN is a regular occurrence, there is less chance of missing the flight.

Thanks, TerryK, for your real-world experience. L it is.

At the risk of stating the obvious, make sure you price these extra segments independent of the OWE, you might find lower fares (though they might be at lower fare classes that don't earn full EQPs).

[QUOTE=Full Score]On a RTW First Class ticket any sectors where First or Business are not offered should be booked into Y Class, not L or M - this change was made quite some time ago by all the airlines. It ensures full bonus miles and Q pts.

However, what AA can't agree on is into which class extra segments should be booked, e.g. in the US, if the ticket originates in, say, CAI, on top of the maximum of six US segments, one is allowed to book two additional economy segments at $150 each. As one is adding segments to a First Class ticket I would have expected these to also be booked into Y Class - one AA rep said "yes", one said "no".[QUOTE]I can confirm that any extra segments that you purchase are always in L (even if on a "1-class" flight -- more on that below). As for Y being used instead of L, the rule is not quite what you state (though similar intent). Specific airlines and in the case of AA, a specific range of flight numbers, book into Y instead of L (these correspond to single class commuter AC/AE flights). If some other flight operated by AA, outside of this range of flight numbers, happens to only offer economy and no F or J, then it still books into L until AA amends the rules! And there are lots of other OW-operated flights with only 1 class that book into L and not Y. So it is hardly correct to say that "this change was made by all the airlines", rather it was made by a few specific airlines for specific flights. The rule is a bit irrational, probably because it is such a niche rule and hasn't had much attention paid to it.

So to summarize:
1. In the US on AA, all six segments of an A class ticket and two additional segments book into L class if A or D are not available, EXCEPT
2. On computer flights using AA Eagle and AA Connection, the six segments book into Y class, but the two additional ones remain in L class.
3. Other airlines have their own rules.

Correct?

Correct. However, I would question whether you were getting good value from your AONE or DONE if all of your NA sectors were on single class aircraft.

Yes.

I would not quite classify it as that. The rules are part of the overall ticket rules. For some reason AA deviated from the rules and allowed certain flights to book in Y.

The rules are not dependant on airlines per se

For 1st class is booked in A, business in D and economy in L

except

AY EI LA LP DOMESTIC and
AA DOMESTIC FLIGHTS 3000-5999

1st and business in Y and economy in L

BA WORLD TRAVELLER PLUS book in T

NOTE: WHEN THE CLASS OF SERVICE FOR THE FARE IS NOT OFFERED BOOK IN THE NEXT LOWER CLASS OF SERVICE USING THE BOOKING CLASSES ABOVE
EXCEPTION - FOR SERVICES WITHIN/BETWEEN THE USA AND CANADA WHERE NO BUSINESS CLASS IS OFFERED BUSINESS CLASS PASSENGERS MAY BOOK AND TRAVEL IN FIRST CLASS SUBJECT TO AVAILABILITY

Other carriers have also deviated to allow 1st and business class ATWs to be booked in Y when on a flight operated as economy only

Dave