On 2006-06-03, john smith wrote:

There is a delay of one or two minutes before the altitude hold will
engage. Be patient.

And in my experience, you don't want to be trying to get the altitude
hold to engage as soon as it possibly will. There seems to be a small
window where it will engage but immediately command a slight nose up/down
rather than just holding altitude. Passengers don't like it!

--
Ben Jackson

http://www.ben.com/