Originally Posted by IluvSQ
Based on my experience, NO.
On one flight AC015, when there was an equipment change resulting in a loss
of J seats, my wife was on a Y fare with upgrade confirmed months before.
At check-in, they told us her upgrade was revoked because she did not
have status, even through she was my companion, and would only guarantee
a J class seat if we paid the fare differential to J.
That led to a long argument with concierge as to what a "confirmed upgrade"
at time of booking meant, and eventually she got it; but my understanding
of the way they did things was that other members with status would
have gotten the UG ahead of her, based on her own status.
I can confirm IluvSQ's scenario based on one personal experience and observation on another (I was flying on a full J thus unaffected) and equipment was switched from an A345 to A343), both within the immediate past seven months.
In the case when I was down graded from “confirmed” upgrade to economy, Customer Solutions later told me (in writing) that all upgrade confirmation is subject to availability. AC has the right to revoke such prior confirmation without compensation. It’s unfair for those who do not want to play aerolotto and pay Y or M fare to secure the so called “confirmation” but the work-around is to avoid the A345 and A330. Go for the 25 J seats B763 first, then the 30 J seats A343 and B763.