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Old 11-14-2006, 06:26 PM   #1  
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Default 135 Jet S/E Climb Perf. in Black & White

During a recent jet recurrent training session in DFW, the subject of Minimum climb performance arose in the classroom. For IFR T/O did you have to have 3.3% or better on one engine or could you just take-off as long as you hadS/E Climb at 2.4% to 1500 AGL. 135 guys had heard of the FAA busting pilots for taking off at high altitude airports IFR but didn't know the publications that were referenced regarding it. After some research we found what we were looking for. It was in the FAA Inspector's Handbook 8400.10 CHG 5, Section 1. Specifically, Para 927 on Page 4-339

Excerpt from 8400.10, para 927 A & B
9 2 7. Takeoff Weights Limited By Obstacles.
To obtain obstacle clearance throughout the takeoff flightpath, operators of transport category and commuter category airplanes must identify obstacles and limit takeoff weight. Obstacles in the takeoff path that are not cleared horizontally must be cleared vertically by at least the amount specified in the certification rule.
A. Definition of Obstacle. Any object inside the airport boundary which is within a horizontal distance of 200 feet of the flightpath or outside the airport boundary within 300 feet of the flightpath, must be considered an obstacle for takeoff computations.

B. Part 135 En Route Obstacle Clearance. FAR 135.181 places en route performance limitations on all IFR passenger-carrying operations.
(1) FAR 135.181(a)(1) effectively prohibits the release of passenger-carrying flights under IFR conditions in single-engine airplanes. The rule does permit over-the-top operations under limited circumstances. The flight must be able to reach VFR conditions within 15 minutes after takeoff. At the point the airplane has flown 15 minutes, the weather below any overcast must be VFR. These conditions must exist at all points on the route, including overhead the destination.

(2) FAR 135.181(a)(2) prohibits the release of multiengine airplanes in passenger-carrying IFR operations or VFR over-the-top operations unless specific conditions are met. The airplane must be able to sustain a failure of the critical engine and climb at a rate of 50 feet per minute at the MEA or 5,000 MSL, whichever is higher. The other circumstance in which a multiengine airplane can be released in IFR conditions or VFR over-the-top conditions is when, after an engine failure, a descent can be made to VFR conditions at or above the MEA.

Excerpt from 8400.10, para 927 E
E. Takeoff Minimums. TERPS criteria is based on the assumption that the airplane can climb at 200 feet per nautical mile (approximately 30:1) to the minimum enroute altitude (MEA) through the takeoff flightpath.
(1) When obstacles penetrate the obstacle clearance plane, the airplane must be able to climb at a steeper gradient or to use higher than standard takeoff minimums to allow the obstructions to be seen and avoided under visual conditions. Authorizations for lower-than-standard takeoff minimums are based on the operator adjusting airplane takeoff weight to avoid obstacles in the takeoff flightpath if an engine fails on takeoff. POIís shall not authorize operators who do not prepare an airport analysis and perform obstacle climb computations to use lower-than-standard takeoff minimums. POIís may approve a system in which the operator makes obstacle clearance computations and performs lower-than-standard visibility takeoffs on specified runways, as opposed to all runways.
(2) The criteria for TERPS does not take into account whether or not the aircraft is operating on all engines. Operators must either show compliance with TERPS criteria with an engine out or have an alternate routing available for use in case of an engine failure. Specific guidance for approval of these procedures is in development and will be included in this handbook at a later date.

For 135 operators, it clearly is governed by law with 14 CFR 135.181 requiring SE climb performance to 5000 or the MEA which ever is higher.

Although not law, the FAA Inspector's Handbook is the FAA's interpretation and I can see where they would construe Part 25 as the governing law over operations as well. I haven't done enough research into Part 25 but I'm assuming the 1st sentence in Para. 927 regarding "clearing obstacles by at least the amount specified in certification" is the 2.4% for 2 engine aircraft. Finally in Para. 927 E the FAA clearly indicates that if you cannot meet TERPS 3.3% or ODP, you will need to have the airport obstacle data and an alternate routing. Ever wonder how some operators launched while others stayed on the ground? Jeppesen and other vendors can provide airport obstacle data and an alternate "emergency route" using the 2.4% climb gradient on a subscription basis. Many Air Carrier's and heavy Biz jets use this data so they can launch with a 2.4% climb gradient instead of the TERPS 3.3%.

I would appreciate others perspective and specifically, is there any publication that may apply to 91 that permits or restricts jet climb performance as that mentioned above.

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Old 11-27-2006, 08:54 AM   #2  
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Man, you just blew my mind, but thanks for the reminders of those regs. I don't think there's anything anywhere that would limit 91 ops in that way. I may be wrong. Thanks for that succint analysis of 135 though.
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Old 11-27-2006, 05:50 PM   #3  
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I love part 91.

Take off minimums, What are take off minimums?
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Old 11-28-2006, 03:38 PM   #4  
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Originally Posted by AVIVIII View Post
I love part 91.

Take off minimums, What are take off minimums?

Yeah, if you're Pt 91, the obstacles just magically disappear if you cage an engine.

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