Originally Posted by
corporate-wage-slave
KTN has never been on BA's or BAEC's systems, to the best of my knowledge. However KTN was / is supported by other GDS interfaces, for example used by a corporate booking system, so KTNs could in certain circumstances populate AA flights on BA bookings. Plus I suspect AA's system had some algorithm on their side of the house for regular flyers. No reason why the passport number shouldn't stick, however, it's best in place before booking, however again a corporate booking system can plonk reservations into life in such a way that they don't read over the BAEC profile information.
Assuming we are both meaning the same thing (where I put my Global Entry-provided TSE pre number), I think you might be mistaken about this. I can enter my KTN now at MMB in the field labelled
"Known Traveller Number(optional)Known Traveller Number or Pass ID for TSA PreCheck and Global Entry. Currently only available on the printed boarding passes (mobile boarding passes are not currently TSA PreCheck enabled) More about TSA Precheck.". Whilst it's not there now (and I don't think was there at first), once upon a time (I think it disappeared in a web site refresh) I could also enter this into my "Update your personal information" profile - in theory, as it never actually stuck there, and neither did my passport info. So I called BAEC gold and got them to put them both in, and it stuck (even though the field was removed) until such time as my passport expired and I updated the passport number, and since then nothing (passport included) has ever stuck again. It's possible my memory may be failing me but ...
Also the checkbox marked "Save time in future by saving these details to my British Airways Profile" never seems to work for me. More accurately the data is saved, but is never actually reused on a new booking even if I book with may BAEC number, so it saves no time at all.
For compatibility with other carriers, I'm travelling today on a Swiss booked United flight operated by LH, and I can't get either passport or KTN to stick with any of their sites.