I know I should know this, but I dont.

I am planning my flights next year to retain my Silver status, and need four flights on BA to qualify.

Does this mean four flights on BA metal, with a BA flightnumber? Or can it be any flight with a BA number, regardless of the metal? Or any flight on a BA plane, regardless of the flight number?

Reason I am asking is that I am looking at a flight witch is booked on AA.com, on a BA plane (from JFK to LHR), but has an IB flight number. Would this count? Or would I have to ensure it books onto a BA flight number to get the miles? Come to think of it, does the fact that it is booked on AA.com mean it won't qualify anyway??

Sorry for being dense. As I said, I should know this, but I am confused.