I might be able to, if I can read from this letter. I wish I could have had it translated more quickly. Nonethless, it says, “Secure Flight collects only the personal information necessary for effective watchlist matching: name, gender, birth date, and if available, a passport number to help ensure accuracy in our checking”.
My understanding is that if the airlines have the passport number, they do share it. If they don't, they don't share it. But it's not collected.
Mr. Jean.