Speed Vs Altitude LearJet!!!
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Join Date: Dec 2003
Location: Planet Earth
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On the twin jet that I fly, there is no "one way" to operate, the company gives us a cost index to input in the "box", the company analyzes a specific route based on the trip length and assigns a CI (cost index), the higher the cost index, the faster the climb and descent speeds based on your companies operating costs.
When in doubt, I fly fast, I figure that's why they chose to fly on a jet!
When in doubt, I fly fast, I figure that's why they chose to fly on a jet!
ECON cruise, LR cruise...
Join Date: Apr 2002
Location: MIRSI hold - give or take...
Age: 52
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What can easily be overlooked is that it's all down to economics - as DreamLand correctly mentioned. We fly small aircraft (change-over probably occurs somewhere around the BBJ-mark or just beyond it) where the main DOC derives from flighttime used. Unless you take fuel from somewhere with ridiculous prices, you'll spend more of your boss' hard earned dosh by using up flight-time.
If you need the range, fly the book figures. If range is no concern, make sure your flight planning program takes into account how you actually operate the aircraft or at least add a good amount to your trip fuel and go balls to the wall.
Another beneficial effect is that you'll never end up climbing higher than your performance allows and will never end up on the wrong side of the drag-curve, and on some aircraft, especially those whose envelope has been extended upwards without modifying the profile (Legacy springs to mind, started off as a FL370-aircraft and now does 410, with the same climb profile), you will find your overall trip time, especially on shorter trips, drops dramatically.
If you need the range, fly the book figures. If range is no concern, make sure your flight planning program takes into account how you actually operate the aircraft or at least add a good amount to your trip fuel and go balls to the wall.
Another beneficial effect is that you'll never end up climbing higher than your performance allows and will never end up on the wrong side of the drag-curve, and on some aircraft, especially those whose envelope has been extended upwards without modifying the profile (Legacy springs to mind, started off as a FL370-aircraft and now does 410, with the same climb profile), you will find your overall trip time, especially on shorter trips, drops dramatically.
