I swear I heard the "A"!.
Of course I couldn't see squat because of the very high contrast narrow-band TV signal.
Armstrong was probably a little too emotional at that point, and after all, not an actor. A minor muff in what he probably was too busy to rehearse can be forgiven.
OK, OK, I played the download, You're right, no "a". I've gotta blow my brain out, now. Man, that's gonna hurt.