Always worth waitlisting if they can they will confirm. Usually in the 24 hrs period after placing on WL.

I see. So when I place a flight on wait list they'll send a request to revenue management, who will then decide to clear it or not? Or does it simply sit there until they decide to open up space.

For those waitlisted, could/can you see two bookings with your booking code one in I-class (the waitlisted) and one in the normal-fare class?

I got one flight in waitlist for I-class but I don't see it in my booking and am wondering whether the agent did it correct. :D

Yes, that's right.
If you see only the I class ticket, you should not be waitlisted anymore.

Are you sure that's the way they do it on A3?
I definately got a new ticket number when my coupons were processed, but not sure if I got a new PNR...which if I did would result in a separate booking rather than being associated with the original one.

For me, it has varied considerably. However, I feel like earlier in the year, I always got a new PNR. These days, (including a flight I am about to board tonight) I have not. Also, a few months ago (July), when waitlisting, it did seem to split the reservation showing 1 in Y and 1 in I. However, this time, (again with the flight I am boarding tonight) it did not do that, and just showed in I once it was confirmed. (Little more than 24 hours after the request was made)
So, honestly, I think they are just working the system. I mean, at the beginning of the year, waitlisting wasn't an option and upgrade was only available if award availability. Now, if there is any business seat, it seems most of the time they will give it to you. So I think they are just trying to maximise the utility of their system.

For me, I ALWAYS get a new ticket number and have ALWAYS had the same PNR. The only slight irregularity seems to be with this new waitlisting that's becoming common. My latest upgrade changed to I class a couple of hours after I called them and was waitlisted, but the ticket number remained the same. It was only the next day when presumably somebody manually re-ticketed it that the actual ticket number changed and I received the email of sucessful upgrade. So it seems that he booking changing to I class online does NOT necessarily mean you've been upgraded yet. I've yet to see what happens with a failed waitlist.

Well these are two different things.

The PNR is the identifier of your booking. The e-ticket is a frozen state of that booking, which can be used for travel.

So your booking can be different than your eticket(s). However any flights that are in confirmed state in your booking, are available to be ticketed. The ticketing process basically means that they take a snapshot of your current booking, and assign an e-ticket number to that snapshot. This is what you then use to travel. This eticket cannot be modified, and needs to be invalided if your booking changes again.

The booking can be changed/updated to whatever they like. In theory they can delete all flights and add totally different ones. There should be no reason to issue a new booking/PNR. Personally I have never seen that happen either - over numerous rebookings with many airlines.

So generally when you are waitlisted they would add a new flight leg to your booking, in I class, with status 'waitlisted'. Once that status changes to 'confirmed' the old flight in Economy class will be removed from the PNR. The last step is that the ticketing department checks if all requirements have been met (eg all taxes have been paid) and if so, issues the frozen e-ticket.

Yep and even some airlines does not update the PNR in Amadeus when you go for an upgrade (miles or paid), they only update in Gabriel system for exemple. But when check in they retrieve the data from their ERP.

Aegean does not work this way and send you a new PNR when you do an upgrade (this is one of the reasons why most of the time you have to a manual request for missing miles when upgrade in I no?)

Do you mean a new E-ticket?
With Aegean, they issue a new e-ticket , but keep the same PNR. As Xandrios explained above.

And therefore this would be correct:-
Yes, because of the new ticket number in I class on the PNR.

You get a new E ticket after upgrades not a new PNR. The PNR always stays the same.

yes, sorry :))

It kinda does, but not always.

My case was - two pax on the same PNR, requested upgrade with coupons, the I space was only available for one pax, so the one upgraded immediately stayed on the old PNR, while the one put on a waitlist was broke out to a new PNR. Hence - change of PNR for the pax on waitlist (got upgraded next day - still on the new PNR).

Just to show the PNR sometimes change ;-)

That's as a result of splitting the booking though - not of upgrading.

Sure it was, but for those not as engaged in the inner workings of airlines back office it could possibly seem to be the other way around. Anyway - i wasn't trying to do anything here, just to show that such a generalisations (as the 'PNR never changes') should be taken with a grain of salt - as per my example.