05takeoff flight path performance

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TAKEOFF FLIGHT

PATH PERORMANCEObstacle Clearance Requirements


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Takeoff Flight Path

The takeoff flight path is considered to begin whenthe airplane has reached a height of 35 above the

surface and continues to the higher of 1500 abovethe surface, or the point the single engine en-routeclimb speed is reached.

Large aircraft have numerous takeoff configurations

which affect departure path profiles. Each time a flap or slat selection is to be retracted an

acceleration is required.

An acceleration during climb with one engineinoperative results in a period of level flight.


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Climb GradientsIn an aircraft with multiple takeoff configurations and flap retraction

schedules a climb gradient must be calculated taking into accounteach period of acceleration.

Climb Gradient:the ratio of the change in height during a portionof a climb, to the horizontal distance traversed in the same timeinterval.

The climb gradient required is predicated on one-engine inoperativeperformance and is expressed as a percentage.

Alt. gained in feet/horizontal distance in feet100=climb gradient Net Climb Gradient:the aircrafts actual one engine inoperative

climb gradient reduced by 0.8%. This 0.8% reduction in actual climb gradient provides an additional

safety margin for obstacle clearance.

The aircraftsnet climb gradientmust meet the required climbgradient of the departure procedure and clear all obstacles by 200horizontally or 35 vertically within the aerodrome boundary and 300horizontally outside the aerodrome boundary.

A standard departure procedure would require a single engine netclimb gradient of 200ft/nm or (200/6076)100=3.3%


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Climb Segments

The takeoff flight path is divided into segments, which relate toaircraft configuration. A typical segmented profile is as follows:

First Segment:from the end of the takeoff distance to thepoint the landing gear is fully retracted. (V2)

Second Segment:the point the landing gear is retracted toan altitude of at least 400 (obstacle dependant). (V2)

Third (Transition) Segment:the horizontal distancerequired to accelerate at a constant altitude to facilitateflap/slat retraction and acceleration to final climb speed.

Final Segment:end of third segment to at least 1500(obstacle dependant) with flaps/slats retracted, max.

continuous power, and final climb speed.


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The minimum climb gradients required for certification by the CARS for two enginetransport aircraft are:

First Segment: positive

Second Segment: 2.4%

Final Segment: 1.2%


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Minimum Certification Performance

For the aircraft certification process minimumperformance requirements are specified in the CARS

for each segment of climb. The aircraft must be capable of obtaining this

minimum performance for all certified weight, altitude,temperature combinations.

Only at the most adverse combinations of weight,altitude, and temperature will aircraft performancerepresent these minimums.

Any conditions more favorable to performance willresult in climb gradients better than the minimum.


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Company Assessed Departures

The standard mile departure gradient is a generic obstacleclearance departure profile which works for most general

aviation operations at most airports. Larger aircraft operating with higher takeoff weights and more

stringent governing regulations commonly do not meet therequired net gradient.

Most operators hire companies who specialize in assessingairports for obstacle clearance requirements, to set up aircraftspecific departure procedures which allow for less restrictiveclimb gradients.

These departure procedures can be quite complex, involving a

number of required gradients at different stages of theprocedure, track changes, and aircraft bank restrictions.


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Noise Abatement Procedures

Noise abatement procedures have been developed

for turbo-jet aircraft in the interest of avoidingdisturbance to noise sensitive areas.

The CAP will include procedures specific to theairport.

There are two established procedures: A and B

Procedure A results in noise relief during the latterpart of the procedure.

Procedure B results in noise relief close to theairport.


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Procedure A

(a) Takeoff to 1 500 feet AAE:(i) takeoff power,

(ii) takeoff flap, and

(iii) climb at V2 + 10 to 20 KT (or as limited by body angle).

(b) At 1 500 feet AAE:

(i) reduce thrust to not less than climb power.

(c) From 1 500 to 3 000 feet AAE:

(i) climb at V2 + 10 to 20KT.

(d) At 3 000 feet AAE:

(i) accelerate smoothly to enroute climb speed with flap retraction onschedule.

AIM RAC 7.6.3


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Procedure B(a) Takeoff to 1 000 feet AAE:

(i) takeoff power(ii) takeoff flap, and(iii) climb at V2 + 10 to 20 KT.

(b) At 1 000 feet AAE:(i) maintaining a positive rate of climb, accelerate to zero flap minimum safemanuvring speed (VZF) retracting flap on schedule, then(ii) reduce thrust consistent with the following:

(A) for high by-pass ratio engines, reduce to normal climb power;(B) for low by-pass ratio engines, reduce power if practicable to

below normal climb power but not less than that necessary tomaintain the final takeoff engine-out climb gradient; and(C) for aeroplanes with slow flap retracting, reduce power at an

intermediate flap setting.

(c) From 1 000 feet AAE to 3 000 feet AAE:

(i) continue climb at not greater than VZF + 20 KT.

(d) At 3 000 feet AAE:(i) accelerate smoothly to en route climb speed using normal climb power.

NOTE: Aeroplanes such as supersonic aeroplanes not using wing flaps for takeoffshould reduce thrust before attaining 1 000 feet AAE but not lower than

500 feet AAE.

05takeoff flight path performance

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