I think that slamer came close to the mark. It's to keep you legal if you're right at the aircraft's upper limit.
In my experience, it seems to be a Boeing thing, to add to your Boeing list novicef, the upper limit for the B777 is 43,100 feet. It's testing my memory and I stand to be corrected, but I recall the limit for the B727 as being 42,100 feet.
Regards,
Old Smokey
Last edited by Old Smokey; 13th May 2006 at 01:50.