That is inaccurate.

AAdvantage members with Platinum status or higher get access to the Flagship Lounges when travelling in any cabin on international long-haul flights and to the Admirals Clubs when traveling in any cabin on international short-haul flights.

The access isn't due to status alone, it's status + the intl route component.

Non-US airline OWE/OWS status (my case) grants access in any flight.

As others have pointed out, if that is the case, then yes you will have access to the American Airlines or OneWorld lounge as the case may be since this is a flight from New York to Santiago connecting in Miami. That LGA to MIA is a domestic segment will not have any bearing since your itinerary is itinerary and that is considered an international flight both in the eyes of AA and the law (in terms of Montreal Convention).

AA Elites do get lounge access based on status alone. However, there are additional rules for them. Namely, they need to be travelling on an international itinerary going somewhere other than North America (except for Mexico City) to be eligible for access. Per the OneWorld site:
Specifically for domestic flights they also state:
Reading this term that means if you are travelling from Boise to Seattle, no you won't have access. But if you are flying from Boise to Brussels, Belgium or Portland to Perth, Australia, then yes you'll have access on those domestic flights since you are not travelling solely on domestic U.S. flights.


My experience as a Qantas OneWorld Sapphire is that I haven't had any issues accessing American lounges on departure, arrival or connection (did that about a dozen times when I was in the US back in October). Most of those flights were solely domestic US. Similar thing for Alaska (except for the arrival bit as that's not allowed). Heck, once I had a late night flight from Seattle to LAX on Alaska and was able to access the Flagship lounge on arrival, no problems whatsoever.

That is mostly true. Lounges can and do limit access for made up reasons as well. For instance, I was refused entry to the British Airways lounge at Seattle as I wasn't on an international flight despite me being a Qantas Gold (OneWorld Sapphire).

Trying to understand the rules. A few days ago, I was arriving to ORD on a domestic AA coach award and accessed the flagship lounge on arrival using BA gold / OWE. I had thought that access on arrival was a OneWorld policy, but I was mistaken.

So was it AA that allowed the entry? BA, since they were paying for it? Or the combination of both?

When you fly AA domestic, as OWE or OWS you are allowed into FL. Regardless of class.

LcS

You are correct that oneworld lounge access rules do not allow access on arrival. You must have a departing oneworld flight. However AA lounges typically allow access on arrival also; This is AA allowing the entry.

Gotcha. Out of curiosity, under what circumstances do AA lounges not allow access on arrival (assuming you stay airside or can get back to airside)?

I think I have FL access on arrival for my situation but just want to check with the brains trust here. Flying San Antonio to Dallas early evening and then have a 14 hour layover and an early morning flight to Atlanta the next day all on one ticket. I am OW Saphhire through Qantas. I have booked overnight accomodation outside the airport but assuming that as I will have my luggage checked through I will be able to access the lounge in Dallas on arrival. TIA

As OW Sapphire with Qantas, yes.

Get access if you’re departing, arriving or connecting to any same-day flight marketed and operated by American or a oneworld® airline (regardless of cabin)

Flagship lounge access exec plat
 

I'm AA exec plat, I've fly Cathay pacific PE to HKG from ORD every other month or so. I know I get lounge access if I layover in lax , but I'm flying out on a Cathay plane. The domestic part of the flight is on a AA route. My question is since I buy the tickets from Cathay, and it's an international route, but the ORD to LAX segment is on AA, am I entitled to flagship access at ORD since the ORD is part of an international itinerary? Thanks

Yes. You can access the ORD FL on arrival and departure in any class of service, even Y, due to your EXP (oneworld emerald) status, when flying Cathay or any oneworld airline on the longhaul segment

Yes. From AA.com: “Get access if you’re departing, arriving or connecting to any same-day flight marketed and operated by American or a oneworld® airline (regardless of cabin).*^”

AA doesn’t usually check through luggage for overnight domestic connections >12 hours. Regardless, you will have access on arrival but may have to travel back from Terminal D (FL) to the terminal you arrived at to retrieve your bags for the night.

Thanks changed flight to be 11 hour connection so hopefully that will be ok. For such a short layover really don't want the hassle of re-checking in the next morning