Back to the original questions:
>With a cruising altitude that high, how long does it take to reach
Without restrictions (traffic or lack of ATC clearance, etc.) AA's 757s can reach FL410 in about 17-20 minutes for normal N/S Calif. flights. Quickest I've done was 16 minutes from brake release at SNA and that was with derated climb power up to FL310!
>...and at what point along the flight do you begin the initial
>descent for, say, Ontario airport? I suppose Avenal VOR is a
>little too soon to begin the descent, but it can't be too far
>past that, otherwise you'd fly right over Ontario airport.
Prior to Avenal as there are some altitude restrictions on the ONT arrivals.
>I get the feeling that if the aircraft is relatively heavy,
Light, not heavy. This is very short flight for a 757.
Someone else writes:
>Those FL410 flights you mention are almost certainly bizjets,
>which have much better performance than big airliners, and
>commonly cruise at at least 41,000 ft on most flights.
I am constantly restricted in both climb and speed by slow climbing and slow flying business jets. Guess it depends upon what type of bizjet and how it is loaded. OTOH, I've never knowingly been holding up a bizjet.