Net Take-off Flight Path??

JetPilot123 · Post by **JetPilot123** » Fri Sep 21, 2007 6:04 pm

going back on course soon but can some one explain net take-off flight path to me again, how its calculated? what is required for clearance?

Thanks

JetPilot123 · Post by **JetPilot123** » Sat Sep 22, 2007 3:27 pm

anyone?

flyinphil · Post by **flyinphil** » Sat Sep 22, 2007 3:58 pm

Gross climb gradient is the best the airplane can do under optimum conditions.

Net Climb Gradient is Gross Climb Gradient LESS 0.8%

Obstacle clearance requirement is 35 ft vertically and 300 feet laterally for FAR 25 certification.

JetPilot123 · Post by **JetPilot123** » Sat Sep 22, 2007 4:03 pm

Thanks. I couldn't remember the .8 from gross.

oldtimer · Post by **oldtimer** » Sat Sep 22, 2007 7:12 pm

It all started with FAR Part 25 or Transport Category airplanes which are airplanes with a MTOW in excess of 12,500 lbs. That has changed lately to be airplanes with a certified seating capacity of 20 paying passengers or more. Net Takeoff flight path is the determination of take-off performance for these larger airplanes. In exxence, the takeoff performance must be the longer of - Take-off to 50 ft X 1.15 or accelerated - stop or accelerate - go. That is the take-off Then there is first segment climb which is after the aircraft is airborne, accelerated to V2 and landing gear is being retracted. Climb must be positive out of ground effect. To achieve this performance, propeller autofeather is required. Second segment climb starts at gear retraction and ends at 400 ft AAE. No configuration changes are made. Minimum climb gradient must be 2.4% but may be degraded by 0.8% to account for performance degration and pilot technique. Third segment climb starts at 400 ft. and is acceleration to Vyse as the flaps are retracted and propeller feathered, if required. Final segment climb is to 1500 ft AAE where it becomes a OEI climb. The figures quoted are the minimum required to meet certification requirements. To clear all obsticals on an unrestricted IFR departure, a minimum clib gradient of 200 ft per nautical mile is required. This is a 3.3% climb gradient. Now, the manufacturer will publish the performance figures the airplane is capable of and the plot can determine if the airplane wll meet the performance requirements. If it cannot, gross weight must be reduced, a longer runway selected or power increased, usually by water/ methanol power enhancement. So there you are. Enjoy.

oldtimer · Post by **oldtimer** » Sat Sep 22, 2007 7:15 pm

OOPS. I dropped a decimal. Climb gradient on an IFR departure should read 3.3%, not 33.

flyinphil · Post by **flyinphil** » Sat Sep 22, 2007 8:03 pm

Good post oldtimer. I only gave him the time. You told him how to build the watch.

pelmet · Post by **pelmet** » Sun Sep 23, 2007 7:47 pm

" Climb must be positive out of ground effect."

"Minimum climb gradient must be 2.4% but may be degraded by 0.8% to account for performance degration and pilot technique."

Just going from memory here, but isn't that for twin engine aircraft only?
2.7% and 3.0% jump to mind for second segment for 3 and 4 engine A/C and something else greater than positive rate for more than 2 engines.