has AA been able to issue usable LAN BPs and have you needed to see a LAN agent at the first LAN departure point? (And more specifically, LAX experience requested.)

the only time I did this was more than a few years ago, so YMMV

AA and LA share Edifact messaging, so Interline Thru-Check-in is actually possible. At the very least, you can get your bags tagged to final destination provided the LA flight departs within 24 hours of your AA bagdrop (and both flights being on the same reservation... separate reservations are harder to accomodate)

the one time I did this was a SFO-AA-LAX-LA-SCL and the AA people at SFO had me go through LAN's counter at LAX to get a boarding pass. My bags where tagged for SCL so I didn't have to worry about them though

I have heard LAN airport people say that AA may give you the boarding pass for the LA flight but they are not sure if AA actually does it.

Anyway, if you'd like to skip LAN's counters at TBIT, just check-in online. You can check-in at LAN.com on T-48 hrs and go back and get your printable boarding pass at T-24

Um, sometimes. My USA departures on LAN have always resulted in pre-chequeado, not an actual BP. I'm trying to avoid the check-in counters at LAX because the T-4 to TBIT sterile walkway should be open by the time of my trip. That said, it has been quite some time since I've OLCI'd for a flight ex LAX.

As everything is on the same PNR, I'm not concerned with proper baggage tags.

If it's the same PNR then AA can issue the BP. If not then if the sterile walkway is open then you can get one from the OW lounge dragons. If it's not then you'll need to see LAN. My experience has been going through MIA and it's been hit and miss.

"pre chequeado" is consistent with a T-48 online check-in (as per TSA rules, LAN is not allowed to issue a boarding pass more than 24 hours prior to departure time for international flights originating in the US)
The only difference between "pre-chequeado/pre checked-in" and "chequeado/checked-in" is in fact the boarding pass issuance.

If you go back to LAN's website (after becoming pre-chequeado) within the T-24 hour window, the website should issue you your boarding pass (if it doesn't, it means they have a bug that needs fixing.. although they probably don't know about it yet)

Thanks for this info. I thought it was a doc check requirement.

It is, on flights inbound the US. That's why the T-24 hour boardin pass is available on flights US->south america but not the other way around