Lead Sled
Sitt'n on the throne...
- Joined
- Apr 1, 2004
- Posts
- 2,066
There are several reasons you cannot use AFM 2nd segment climb data in meeting TERP's criteria. First, all the one engine-out climb flight path data (1st, 2nd, and final segment climb charts) are only good to 1,500 above the runway (however, some manufacturers have gone beyond this point up to 3,000 to 5,000 feet) and CANNOT be used to the heights demanded of certain DP's such as is the case of KASE, 7,800 ft to 14,000 ft. 2nd segment climb data is generally only valid to 400 ft above runway, the point where 2nd segment ends. Second, the differences in climb terminology. Most 2nd segment climb gradient charts in AFM's give the available NET climb gradient so that when you apply this to the flight path charts or computer program you get a resulting NET flight path. TERP's climb requirements are based on actual performance, NOT an already an already reduced NET climb gradient. Then there's the consideration of 5 minute limitation on takeoff thrust. Many DP's require climb gradients to significantly high altitudes that would exceed the limitation on takeoff thrust, not to mention a shallowing climb gradient due to density altitude changes as you climb. Remember if you try to use 2nd segment climb, you'll only meet that climb gradient if you keep V2, takeoff flaps, and takeoff thrust and that climb gradient is generally valid only at 400 ft above the runway. Additionally, the charts assume essentially "wings level" flight (I don't remember the exact bank angle limit and my files are at home.) and many DPs involve turns that would exceed these bank angle limitations.Really? You'll have to explain that to me.
The chart doesn't know what altitude your departure airport is, so if you tell it that you need to maintain 800 ft/nm to 10,000 feet and you are able to achieve that from 8500 to 10,000...then it stands to reason that you would be able to achieve it at less than 8500. Right?
I'm not questioning you, just wondering if I correctly understand the second-segment climb tables. (Lear takes 2nd segment all the way to 1500)
As for airport analysis, I agree 100%. I used it for years in part 121 and our department recently started using it part 91. I feel much more comfortable with their calculations then with me ham-fisting the charts to get runway limit or climb limit.
Aircraft "1-engine out" part 25 certification requirements only get us to 1500' AGL on takeoff, after which we immediately transition into the enroute all-engine TERPS climb. I guess that the original intent was that if we could safely get up to pattern altitude after losing an engine on takeoff we could bring the airplane back around for a landing. The enroute climb phase is based on all engine operation. If an engine is lost during that phase, it is an emergency, justifying the use of "alternate departure procedures" as provided by folks like APG or Jeppesen. (The alternate procedure for ASE isn't all that limiting, but it's a pretty demanding procedure - one best practiced a time or two in the sim.)
LS