Beware of codeshares!

If you decide to book a codeshare, no matter how seamless the airlines’ marketing departments make it sound, the following will apply:

Points and miles accrual:
Sometimes, a codeshare might be a good alternative pointswise.

Please note that the calculator at AY.com doesn't work for codeshare flights. You can select "Finnair Codeshare" as carrier, but it does not recognize status bonuses or ticket types (Basic/Value etc) even though you will get status bonus when crediting to AY+, and to some codeshare destinations, AY ticket types are available.

If you’re on AY flight number, you will always earn AY+ points, regardless of carrier. In the 100 % category you earn 1 point / km. In J, you earn the usual 200 % regardless of carrier. You will also earn the usual status bonus.

In some cases (seemingly in cases where the destination is served by both AY and partner metal), you may earn points according to zones.

If you’re on AY flight number and your flight is OW-operated, you will earn points/miles in all OW programmes according to said programme’s AY earning table.

If you’re on OW flight number and AY metal, you will earn AY+ points or points/miles in all OW programmes according to said programme’s earning table of your ticketed airline.

However, if you’re on *A flight number and AY metal, you will earn zero points in any programme (CA, TP). QUESTION: Is this really true? If you’re on HEL-PEK and CA flight number, will you at least earn points in the CA programme? Or in the TP programme for HEL-LIS?

Seat assignments:
Hit and miss depending on the airlines involved, the agent you talk to and other random criteria. Often, it won’t work at all, but sometimes a good agent manages to assign a seat. (At OLCI, will you be given a random seat, or is there a choice? Are many seats blocked at T-36?)

Economy Comfort on longhauls:
Not available to codeshare pax. Not for free for Platinums, and not against a charge for anyone. (Are these seats blocked at OLCI?) Sometimes, Y+ seats are sold at check-in, the gate or on the plane before departure. These are most likely available to codeshare pax. Can anyone confirm?

Pre-order meals in J:
Not available at MMB. A good agent will be able to assign a meal if you call (maybe chat, too).

Special meals (Y or J):
Works normally, however, one might need to contact CS.

Pre-order inflight sales:
Works normally.

Upgrades:
Not available on codeshare. You will need AY metal and AY flight number. The only exception would be a paid upgrade at the airport. See https://www.flyertalk.com/forum/finnair-finnair-plus/1842907-big-upgrade-thread-all-you-need-know-about-ay-upgrades.html for details.

OLCI:
Used to be problematic but this is mostly solved. You can OLCI at AY.com for AY-operated flights regardless of the flight number. The AY system recognizes all sorts of booking references and you may enter eg. your AA record locator on the AY check-in page.

What about AY flight numbers on other carriers? Do all carriers allow OLCI and recognize the AY/Amadeus booking ref?

Lounge access:
If you’re on OW metal and OW flight number, no problems. You may enter based on OW status or J ticket.

If you’re on AY flight number but non-OW metal, or if you’re on non-OW flight number and AY metal, you may or may not have lounge access. A list would be great.
- French domestic flights operated by AF, with AY flight number, will gain lounge access at CDG (what about other French airports?)

Schedule changes:
When the operating carrier makes a schedule change or cancellation, the ticketing carrier should be the one that you deal with. But this is not always the case, and airlines seem to accuse one another, and sometimes no one takes responsibility if the alternative you are presented with is not satisfactory.

IRROPS:
No experience. For last minute IRROPS, the operating carrier shuld be responsible.