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SUBPART H PERFORMANCE CLASS B AEROPLANES ALLEVIATION AND METHOD OF CALCULATING PERFORMANCE. BASIC IDEA. JAR-OPS 1.535 (a)(3) assumes that engine failure occurs at the point on the all engine take-off flight path where visual reference for the purpose of avoiding obstacles is lost.

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SUBPART H PERFORMANCE

CLASS B AEROPLANES ALLEVIATION AND METHOD OF

CALCULATING PERFORMANCE

(C) Olli Hänninen, FCAA


BASIC IDEA

JAR-OPS 1.535 (a)(3) assumes that engine failure occurs at the point on the all engine take-off flight path where visual reference for the purpose of avoiding obstacles is lost.

This point means the ceiling or VV (=vertical visibility) as reported in METAR.

 Calculations do NOT ensure obstacle-free flight path if engine failure occurs before ceiling or VV.

(C) Olli Hänninen, FCAA


GRAPHIC ILLUSTRATION

(C) Olli Hänninen, FCAA


WHAT ABOUT ENGINE FAILURE BELOW CEILING?

Appendix 1 to JAR-OPS 1.430 paragraph (a)(3)(ii) ”ensures” possibility to avoid obstacles or make a forced landing broadly in the direction of the take-off (see also IEM OPS 1.535):

(C) Olli Hänninen, FCAA


Appendix 1 to JAR-OPS 1.430 paragraph (a)(3)(ii) EFFECT ON TAKE-OFF WEIGHT

  • Definition as presented above:

  • engine feilure height = ceiling or VV (vertical visibility)

    • Ceiling is high  Two-engine segment is long

    •  Take-off weight is high

    • Ceiling is low  Two-engine segment is short

    •  Take-off weight is low

  • The better the weather, the higher the take-off weight.

  • Pilots can either reduce the take-off weight or wait for better weather.

  • (C) Olli Hänninen, FCAA


    AEROPLANES WITH VERY POOR PERFORMANCE

    • Aeroplanes with very poor performance may not be able to maintain positive take-off climb gradient in case of engine failure. For these aeroplanes the above presented complies:

    • ”1500 m is also applicable if no positive take-off flight path can be constructed.”

    • If ceiling is above 300 ft and RVR/visibility is 1500 meters or greater THEN OBSTACLES NEED NOT BE CONSIDERED. Only runway length is needed to considere.

    (C) Olli Hänninen, FCAA


    CALCULATING THE FLIGHT PATH

    JAR-OPS 1.535, Appendix 1 to JAR-OPS 1.525(b) and

    AMC OPS 1.535(a) represent methods how to calculate average climb gradients for two-engine and one-engine segments:

    Example from AMC OPS 1.535(a):

    There is only little information on performation of aeroplanes of performance class B in their Airplane Flight Manuals (AFM). Normally at least take-off run distance and two-engine & one-engine climb gradients are presented in the AFM. Yet that information is adequate for flight path approximation.

    However the information concerning contamined runways is not included neither in AFM nor in JAR-OPS 1.

    (C) Olli Hänninen, FCAA


    CONTAMINED RUNWAYS

    JAR-OPS 1.530 (c)(4) requires that take-off runway’s condition is considered.  AMC OPS 1.530(c)(4) represent’s correction factors for few conditions only:

    What about slush, snow and ice?  CAA Finland made a study on this subject: Aeroplane acceleration data (Beech King Air C90 and Piper PA-31-350 Chieftain) was recorded with differential GPS. Acceleration data was then processed according to AMJ 25X1591 (AMJ for JAR 25; nowadays withdrawn and waiting for revision). Results to the study are presented on the following page.

    (C) Olli Hänninen, FCAA


    CORRECTION FACTORS FOR CONTAMINED RUNWAYS

    Above mentioned study resulted as 3 tables.

    Example is shown below.

    (C) Olli Hänninen, FCAA


    HOW TO OBTAIN INFORMATION ON OBSTACLES?

    • Obstacle information should be represented in AIP. Until now only Finland has published both AOC-A and AOC-C obstacle information in the AIP. Therefore alternate methods are needed. Ofcourse if the aeroplane can follow appropriate SID-method then the obstacles are cleared, but class B aeroplanes are usually not capable to do this.

    • We can use the opposite runway’s non-precision approach method for take-off. Suitable methods are: omnidirectional departures, NDB, VOR/DME…

      Two last mentioned use obstacle clearances of 75, 150 and 300 m depending on fix’s distance from the threshold. It is evident that if the aeroplane can fly the opposite runway’s non-precision approach prosedure upwards then it will have sufficient obstacle clearances. These procedures all have adequate obstacle clearances in the horizontal plane.

    (C) Olli Hänninen, FCAA


    OMNIDIRECTIONAL DEPARTURES

    Omnidirectional departures represent procedure design gradient (PDG) until a certain height and after that height 3,3% gradient is required. Obstacle-free surface is still only 2,5 % so one-engine climb gradient is required to be 2,5 % (possible for most of the class B aeroplanes).

    (C) Olli Hänninen, FCAA


    USING OPPOSITE RUNWAY’S NON-PRECISION APPROACH -CHART

    • Aeroplane must climb until OCA(H) (= 500 ft) before the DEP.

    • Aeroplane must climb and reach each fix’s height (= 1520 ft) on given horizontal distances (= 4,6 nm).

    NOTE: Each height may be subtracted by appropriate obstacle clearance (75, 150 or 300 m), but 50 ft according to JAR-OPS 1.535(a) shall be added to resulting height.

    (C) Olli Hänninen, FCAA


    HOW TO REPRESENT CALCULATIONS FOR PILOTS?

    • Pre-flight performance calculations must be easy to be used.

    • Variables affecting on performance are the following:

      • -power setting

      • -outside air temperature

      • -presure altitude / QNH

      • -take-off weight

      • -wind

      • -runway contaminants

      • -obstacle height

      • -ceiling / vertical visibility = assumed engine failure height

    • Computer program would be ideal to do performance calculations, but it is the most expensive option.

    •  How to represent 8-dimensional information on 2-dimensional paper? See example slides on how Finnish operators have solved the problem.

    (C) Olli Hänninen, FCAA


    Flight path approximation and obstacle clearances can be calculated as is presented above in this memo. These methods are used by many operators in Finland. This calculation however requires experticing and is done by consultants.

    All feedback is welcomed! Please contact:

    Olli Hänninen

    Inspector, Flight Operations

    CAA Finland

    Address: Ilmailutie 9, 01531 VANTAA

    Telephone: +358 (0)9 8277 2422

    Email: [email protected]

    (C) Olli Hänninen, FCAA


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