Some time back, when I was at a railroad fan web site (was it this one?), a moderator informed me that the air horn on a diesel electric locomotive is referred to as a "whistle", and NOT as a "horn", because that is in keeping with a tradition of the railroad.
But, I have yet to read ANY posted comment, either in this forum or in any other, identifying an air horn on a locomotive as a "whistle".
Does anyone know anything about this?
Since being told that, I now refer to a locomotive air horn as a locomotive whistle, but I think I'm the only person doing that.