When there is written "this SID requires a minimum climb gradient of 400' per NM up to 5000'", what do they...

Question

... mean with 5000'.... 5000 ft over GND, or when you pass 5000 with your current QNH altimeter?

Answer 1

I agree with the above posters. I understand your question to be asking why it is written. Normally things like this are listed on the SID for you to abide by because there is an obstruction that you must clear. Using a 400'/nm climb gradient will get you over the obsticle with required clearance. My 2cents!

Answer 2

MSL, which is what you read on your altimeter.

This std instr departure requires climb rate of 400ft per horizontal nmile.If you are climbing at 180 kt, you are doing 180/60 knots/min. = 3 nmile per minute. 3 x 400' = 1200 ft/min climb rate until 5000MSL.

Answer 3

5,000 ft MSL (altitude shown on your altimeter when you have the proper altimeter setting dialed in the Kollsman window).  400' per NM can be converted into required FPM climb by the following formula...

Ground Speed/60 x Climb Gradient (in this case...400) = required climb expressed in FPM (Feet per minute)

So say your ground speed is 250 kts.  (250/60) x 400 = 1,666 fpm

You would have to climb at a minimum of 1,666 fpm up to 5,000 ft MSL to meet the requirements of this SID.

Answer 4

not a pilot i guess huh?