Minimum Climb Gradient Calculation Speed
Greetings...
I've heard of a recent discussion about which is the proper correct way of calculating your rate of climb for a minimum climb gradient given in percentage in a SID.
The basic is, a standard (if not published also) minimum climb gradient of 3.3%, with an aircraft climbing at 150 knots.
The standard formula would be 150 * 3.3 = 495.
Round up to the next upper 50, and you have 500 feet per minute of minimum rate of climb.
The question is:
Which speed do you use?
Indicated Airspeed, True Airspeed, Ground Speed?
And, can someone direct me to official documents regarding which speed you actually use? (ICAO, FAA, JAA, SOP, FCOM, etc. you name it)
The main issue here is, some say is Indicated Airspeed (a teacher of basic navigation class included).
Others say it's Ground Speed, or in the difficulty in obtaining wind data, TAS.
It makes perfect sense to me to use Ground Speed, where in a condition of a strong tailwind you have a real danger in performing below the gradient and encountering obstacles.
Please, insights from Heavy, Big, Mid, and Small aviation are much welcome!
Last edited by Pugachev Cobra; 29th Mar 2011 at 13:22.