3 Takeoff Performance Basics What is the Gross Takeoff Flight Path ?It is the vertical flight path that a new aircraft flown by test pilots under ideal conditions would achieve. It is adjusted for the Minimum Engine. It starts where the aircraft passes 35ft and ends at a minimum of 1500 ftWhat is the Net Takeoff Flight Path ?This is the vertical flight path that could be expected in operation with used aircraft. It also starts at 35ft and ends at a minimum of 1500ft
4 Takeoff Performance Basics The Net Gradient would be calculated as follows:Gross Gradientp% x DNet GradientDistance = D
5 Takeoff Distances RUNWAY - This is the ACN capable hard surface CLEARWAY - This is an area, under the control of the airport, 152 m (500 ft) minimum width, with upward slope not exceeding 1.25%. Any obstacles penetrating the 1.25% plane will limit the ClearwaySTOPWAY - A surface capable of supporting the aircraft in an RTO. Its width must be greater than or equal to that of the runway. It may not be used for landingsACN - Aircraft Classification NumberPCN – Pavement Classification NumberThe runway must be such that PCN ACN
7 Takeoff DistancesTORA- TakeOff Run Available. This is the physical runway limited by obstacle free requirementsASDA - Accelerate-Stop Distance Available. This is the distance available for accelerating to V1 and then stopping. It may include the physical runway and any stopway availableTODA - TakeOff Distance Available. This is the distance available to achieve V2 at the appropriate screen height. It may include physical runway, stopway and clearwayNote: Not more than ½ the Air Distance may be in the Clearway (Air Distance is distance from lift-off to 35 ft)The Takeoff Run is defined as the distance from brake release to ½ the Air DistanceWet Runway calculations do not allow use of Clearway
8 Takeoff Performance Basics The Takeoff Phase is from brake release to 1500 ft or the point where the last obstacle has been cleared, if higherThree basic limitations must be taken into account:Field LengthClimb GradientsObstacle ClearanceOther limitations are also restrictive and are covered during discussion on these basic limitations. They are:StructuralTire SpeedBrake Energy
10 V1 “official definition” Takeoff SpeedsV1 “official definition”“…pilot's initiation of the first action (e.g. applying brakes, reducing thrust, deploying speed brakes) to stop the aeroplane during accelerate-stop tests…”JAR (a)JAR (a)V1 must be established in relation to VEF as follows:(1) VEF is the calibrated airspeed at which the critical engine is assumed to fail. VEF must be selected by the applicant, but may not be less than VMCG determined under JAR (e).(2) V1, in terms of calibrated airspeed, is selected by the applicant; however, V1 may not be less than VEF plus the speed gained with the critical engine inoperative during the time interval between the instant at which the critical engine is failed, and the instant at which the pilot recognises and reacts to the engine failure, as indicated by the pilot's initiation of the first action (e.g. applying brakes, reducing thrust, deploying speed brakes) to stop the aeroplane during accelerate-stop tests.
11 Takeoff SpeedsV1, the Takeoff « action » speed, is the speed used as a reference in the event of engine or other failure, in taking first action to abandon the take-off.The V1 call must be done so that it is completed by V1.V2VEFV135’VEFV1
12 Takeoff SpeedsVRVR is the speed at which rotation is initiated, so that in the case of an engine failure, V2 will be reached at a height of 35 feet using a rotation rate of 2º-3º / secondRegulations prohibit a RTO after rotation has been initiated, thus VR must be greater than V1. VR V1JAR (e)VR in terms of calibrated air speed, must be selected in accordance with the conditions of sub-paragraphs (1) to (4) of this paragraph:(1) VR may not be less than--(i) V1;(ii) 105% of VMC;(iii) The speed (determined in accordance with JAR (c)(2)) that allows reaching V2 before reaching a height of 35 ft above the take-off surface; or(iv) A speed that, if the aeroplane is rotated at its maximum practicable rate, will result in a VLOF of not less than 110% of VMU in the all-engines-operating condition and not less than 105% of VMU determined at the thrust-to-weight ratio corresponding to the one-engine-inoperative condition, except that in the particular case that lift-off is limited by the geometry of the aeroplane, or by elevator power, the above margins may be reduced to 108% in the all-engines-operating case and 104% in the one-engine-inoperative condition. (See ACJ (e)(1)(iv).)(2) For any given set of conditions (such as weight, configuration, and temperature), a single value of VR, obtained in accordance with this paragraph, must be used to show compliance with both the one-engine-inoperative and the all-engines-operating take-off provisions.(3) It must be shown that the one-engine-inoperative take-off distance, using a rotation speed of 5 knots less than VR established in accordance with sub-paragraphs (e)(1) and (2) of this paragraph, does not exceed the corresponding one-engine-inoperative take-off distance using the established VR. The take-off distances must be determined in accordance with JAR (a)(1). (See ACJ (e)(3).)(4) Reasonably expected variations in service from the established take-off procedures for the operation of the aeroplane (such as over-rotation of the aeroplane and out-of-trim conditions) may not result in unsafe flight characteristics or in marked increases in the scheduled take-off distances established in accordance with JAR (a). (See ACJ No. 1 to JAR (e)(4) and ACJ No. 2 to JAR (e)(4).)
13 Takeoff SpeedsV2JAR(b) V2MIN, in terms of calibrated airspeed, may not be less than—1·13 VSR for—(i) Two-engined and three-engined turbo-propeller powered aeroplanes; and(ii) Turbojet powered aeroplanes without provisions for obtaining a significant reduction in the one-engine-inoperative power-on stall speed;(2) 1·08 VSR for—(i) Turbo-propeller powered aeroplanes with more than three engines; and(ii) Turbojet powered aeroplanes with provisions for obtaining a significant reduction in the one-engine-inoperative power-on stall speed: and(3) 1·10 times VMC established under JAR(c) V2 in terms of calibrated airspeed, must be selected by the applicant to provide at least the gradient of climb required by JAR (b) but may not be less than--(1) V2MIN;(2) VR plus the speed increment attained (in accordance with JAR (c)(2)) before reaching a height of 35 ft above the take-off surface; and(3) A speed that provides the manoeuvring capability specified in JAR (g).V2 is the takeoff safety speed. This speed will be reached at 35 feet with one engine inoperative.
14 SPEED OF ENGINE FAILURE RELATIVE TO VEF Takeoff SpeedsEffects on the screen height of continuing a takeoff with an engine failure prior to VEF35 FtHEIGHT AT END OF TODA10 Ft2 Engine1 secSPEED OF ENGINE FAILURE RELATIVE TO VEF
15 Takeoff Speeds V1(MCG) - The Minimum Ground Control Speed This is the speed at which, in the case of a failure of the Critical Engine, it is possible to control the aeroplane by aerodynamic means only without deviating from the runway centreline by more than 30 ft, while maintaining takeoff thrust on the other engine(s). Maximum rudder force is restricted to 68 Kg (150 lbs)In demonstrating V1(MCG), the most critical conditions of weight, configuration and CG will be taken into considerationCrosswind is not considered in V1(MCG) determinationObviously VEF must be greater than V1(MCG) , or the aircraft would be uncontrollable on the ground with an engine inoperative:VEF V1(MCG)JAR (e)VMCG, the minimum control speed on the ground, is the calibrated airspeed during the take-off run, at which, when the critical engine is suddenly made inoperative and with its propeller, if applicable, in the position it automatically achieves, it is possible to maintain control of the aeroplane with the use of the primary aerodynamic controls alone (without the use of nose-wheel steering) to enable the take-off to be safely continued using normal piloting skill. The rudder control force may not exceed 150 pounds (68·1 kg) and, until the aeroplane becomes airborne, the lateral control may only be used to the extent of keeping the wings level. In the determination of VMCG, assuming that the path of the aeroplane accelerating with all engines operating is along the centreline of the runway, its path from the point at which the critical engine is made inoperative to the point at which recovery to a direction parallel to the centreline is completed, may not deviate more than 30 ft (9·144 m) laterally from the centreline at any point. VMCG must be established, with--(1) The aeroplane in each take-off configuration or, at the option of the applicant, in the most critical take-off configuration;(2) Maximum available take-off power or thrust on the operating engines;(3) The most unfavourable centre of gravity;(4) The aeroplane trimmed for take-off; and(5) The most unfavourable weight in the range of take-off weights. (See ACJ (e).)
16 Takeoff Speeds VMC - The Minimum Control Speed This is the speed, when airborne, from which it is possible to control the aeroplane by aerodynamic means only with the Critical Engine Inoperative while maintaining takeoff thrust on the other engine(s)The demonstration is made with not more than 5º Bank into the live engine, Gear retracted (as this reduces the directional stability) and the most Aft CG (as this reduces the Rudder Moment.)(VMC may increase as much as 6 Kts. / º Bank from demonstration with wings level and Ball centred)JAR(b) VMC is the calibrated airspeed, at which, when the critical engine is suddenly made inoperative, it is possible to maintain control of the aeroplane with that engine still inoperative, and maintain straight flight with an angle of bank of not more than 5°.(c) VMC may not exceed 1·13 VSR with--(1) Maximum available take-off power or thrust on the engines;(2) The most unfavourable centre of gravity;(3) The aeroplane trimmed for take-off;(4) The maximum sea-level take-off weight (or any lesser weight necessary to show VMC);(5) The aeroplane in the most critical take-off configuration existing along the flight path after the aeroplane becomes airborne, except with the landing gear retracted;(6) The aeroplane airborne and the ground effect negligible.
17 Field Length CriteriaThe Takeoff distance required for a given weight and given V1 is the greater of three different distances:Actual All-Engine Takeoff Distance x 1.15Actual All-Engine Takeoff Distance (As Demonstrated in Tests)V > V235 ftV115% Safety MarginOne Engine Inoperative Takeoff DistanceV2JAR Take-off distance and take-off run(a) Take-off distance on a dry runway is the greater of--(1) The horizontal distance along the take-off path from the start of the take-off to the point at which the aeroplane is 35 ft above the take-off surface, determined under JAR for a dry runway; or(2) 115% of the horizontal distance along the take-off path, with all engines operating, from the start of the take-off to the point at which the aeroplane is 35 ft above the take-off surface, as determined by a procedure consistent with JAR (See ACJ (a)(2).)(b) Take-off distance on a wet runway is the greater of--(1) The take-off distance on a dry runway determined in accordance with sub-paragraph (a) of this paragraph; or(2) The horizontal distance along the take-off path from the start of the take-off to the point at which the aeroplane is 15 ft above the take-off surface, achieved in a manner consistent with the achievement of V2 before reaching 35 ft above the take-off surface, determined under JAR for a wet runway. (See ACJ 113(a)(2).)(c) If the take-off distance does not include a clearway, the take-off run is equal to the take-off distance. If the take-off distance includes a clearway--(1) The take-off run on a dry runway is the greater of--(i) The horizontal distance along the take-off path from the start of the take-off to a point equidistant between the point at which VLOF is reached and the point at which the aeroplane is 35 ft above the take-off surface, as determined under JAR for a dry runway; or(ii) 115% of the horizontal distance along the take-off path, with all engines operating, from the start of the take-off to a point equidistant between the point at which VLOF is reached and the point at which the aeroplane is 35 ft above the take-off surface, determined by a procedure consistent with JAR (See ACJ (a)(2).)(2) The take-off run on a wet runway is the greater of--(i) The horizontal distance along the take-off path from the start of the take-off to the point at which the aeroplane is 15 ft above the take-off surface, achieved in a manner consistent with the achievement of V2 before reaching 35 ft above the take-off surface, determined under JAR for a wet runway; or35 ftVEFV1VEFV1One Engine Inoperative Accelerate-Stop Distance
18 Field Length CriteriaThe greater of the 3 distances is the JAR Field Length requiredIf V1 is chosen such as the 1-Engine-Inoperative Accelerate-Go and Accelerate-Stop distances are equal, the necessary field length is called Balanced and the corresponding V1 is known as a Balanced V1Balanced V1
19 RANGE OF POSSIBLE WEIGHTS Field Length CriteriaFixed Runway LengthMTOWACCELERATE GORANGE OF POSSIBLE WEIGHTSACCELERATE STOPBALANCED V1V1
20 JAR 25 Takeoff Flight Path 1500 Ft or Clear of ObstaclesFlap retraction 400 Ft MinLift-OffGear RetractedCleanV2V2AccelerationCleanTO Thrust Max 5 minMCTJAR (a-c)(a) Take-off; landing gear extended. (See ACJ (a).) In the critical take-off configuration existing along the flight path (between the points at which the aeroplane reaches VLOF and at which the landing gear is fully retracted) and in the configuration used in JAR but without ground effect, the steady gradient of climb must be positive for two-engined aeroplanes, and not less than 0·3% for three-engined aeroplanes or 0·5% for four-engined aeroplanes, at VLOF and with--(1) The critical engine inoperative and the remaining engines at the power or thrust available when retraction of the landing gear is begun in accordance with JAR unless there is a more critical power operating condition existing later along the flight path but before the point at which the landing gear is fully retracted (see ACJ (a)(1)); and(2) The weight equal to the weight existing when retraction of the landing gear is begun determined under JAR(b) Take-off; landing gear retracted. In the take-off configuration existing at the point of the flight path at which the landing gear is fully retracted, and in the configuration used in JAR but without ground effect, the steady gradient of climb may not be less than 2·4% for two-engined aeroplanes, 2·7% for three-engined aeroplanes and 3·0% for four-engined aeroplanes, at V2 and with--(1) The critical engine inoperative, the remaining engines at the take-off power or thrust available at the time the landing gear is fully retracted, determined under JAR , unless there is a more critical power operating condition existing later along the flight path but before the point where the aeroplane reaches a height of 400 ft above the take-off surface (see ACJ (b)(1)); and(2) The weight equal to the weight existing when the aeroplane's landing gear is fully retracted, determined under JAR(c) Final take-off. In the en-route configuration at the end of the take-off path determined in accordance with JAR , the steady gradient of climb may not be less than 1·2% for two-engined aeroplanes, 1·5% for three-engined aeroplanes, and 1·7% for four-engined aeroplanes, at VFTO and with--(1) The critical engine inoperative and the remaining engines at the available maximum continuous power or thrust; and(2) The weight equal to the weight existing at the end of the take-off path, determined under JAR35 ft1st Segment2nd Segment3rd Segment4th SegmentTWIN>02.4%accelerationor 1.2% avail.1.2%
21 Obstacle ClearanceFor Obstacle Clearance a Net Takeoff Flight Path is consideredIt is not demonstrated, but rather calculated from the Gross Flight Path by reducing the gradients by a safety margin:Twin 0.8%It also will take wind into account, using 50% of the Headwind Component and 150% of the Tailwind Component, thus giving a further safety margin.The Net Takeoff Flight Path must clear all obstacles by 35 Ft
23 Obstacle ClearanceThe minimum height for flap retraction is 400ft AAL (gross)TNT A B737 : we use 800 ft AAL minimumIf there is a high obstacle in the 3rd or 4th segment, we could extend the second segment to ensure that the obstacle was cleared by 35ft. Provided it still remains in the 3rd or 4th SegmentWe now have a Minimum Gross and Minimum Net Acceleration Height which is then corrected for elevation and temperature to give a Minimum Gross Acceleration Altitude
24 Minimum Gross Acceleration Height Minimum Net Acceleration Height Obstacle ClearanceMinimum Gross Acceleration HeightExtended Second SegmentMinimum Net Acceleration Height35 Ft400 Ft
25 Acceleration Altitude The extension of the second segment and raising of the EFFRA (JAR : EOAA) is limited as takeoff thrust must be maintained until acceleration altitude is attainedThe Takeoff Thrust is limited to 5 minutes and this restricts the extension of second segmentEFFRA: Engine Failure Flap Retraction AltitudeEOAA: Engine Out Acceleration Altitude
26 Engine Failure Procedure The Standard Engine Out Procedure (EOP) is therefore:Maintain Runway TrackClimb to the EFFRA at V2Accelerate and Retract FlapsSet MCT (max 5 min after TO power setting)Climb to the 1500 ft AGL at Flap up man. speedAnd then???
28 Obstacle ClearanceOnly obstacles within a certain lateral distance of the flight path are taken into account in performance calculationsFor each runway, Obstacle Cone is constructed for Straight Ahead or Turning Engine Out Procedures (EOP)Wind is not considered therefore correct tracking is importantThere is not a large margin for error for a jet airplane
29 Obstacle Clearance Flight Path 3000 ft300 ftwidth =0.125 x D21600 ft3000 ft3000 ft300 ft
31 Obstacle ClearanceBank Angle has a large effect on the climb performance and therefore Obstacle ClearanceGRADIENT2.4%0.6%1.8%BANK ANGLE
32 Optimisation - Improved climb Depending on the design of the aircraft and on the flap setting, the maximum climb angle speed is usually 15 to 30 kts higher than 1.13 VSRHowever, the selection of a V2 higher than the minimum will increase TODThe V2/VS optimisation is called « Improved Climb Method »This method consists thus in increasing the climd limited TOW at the expense of the field limited TOW. It is only applicable if runway length permitsIn order to obtain consistent field length, V1 and VR have to increase if V2 increases: if the runway allows an increase of V2, thus an increase in TOD, it will also allow an increase of the ASD, thus also of V1
33 Optimisation - Improved climb DragDrag CurveGiven TOWTO FlapsGear UPDepending on Flap Setting,the Max Angle Speed istypically 1.13 VS + 15 to 30 KtsVs1.13Vs1.28VsEAS
34 Optimisation - Improved climb In order to achieve the higher V2, the VR speed must be increasedThe V1 speed must also be increased to ensure that there is sufficient runway to accelerate, lose and engine and be able to continue the takeoff at higher weightAs V1 is higher, the VMBE speed must be checked for brake energy limits as this may become limiting
35 Reduced Thrust Takeoff When the actual TOW is below the maximum allowable TOW for the actual OAT, it is desirable to reduce the engine thrustThis thrust reduction is a function of the difference between actual and maximum TOWJAA requires that the reduced thrust may not be less than 75% of the full takeoff thrust. Specific figures may apply for different airplanes/engines
36 Reduced Thrust Takeoff Assumed temperatureIf the actual TOW is less than the maximum weight for the actual temperature, we can determine an assumed temperature, at which the actual weight would be equal to the maximum allowed TOWMAX TOWFlat rated thrustEGT limitedthrustAllowedTOWAct TOWHaving determined this assumed temperature, we can compute the take-off thrust for that temperatureOATAssumed temperatureTemp
37 Reduced Thrust Takeoff LimitationsSince thrust may not be reduced below 75% of the full thrust, a max assumed temp can be determinedThe assumed temperature may not be less than the OATNo reduced thrust on standing water, and on contaminated or slippery runwaysNo reduced thrust with antiskid inop or PMC OFFNo reduced thrust for windshear, low visibility takeoff
38 Reduced Thrust Takeoff It’s safeOAT = 30°C weight is MTOWV1When applying the assumed temp method, the minimum legal performances are garanteed. There is even a safety margin, result of the following facts:The air is denser than it would be if the temperature was really 30°C in our example, and V1 is obtained earlier on the runway.Since V1 in an indicated airspeed, it will correspond to a lower TAS in the second case (due to different air density as well), further reducing the distance required for acceleration to V1.From these considerations results a margin at V1.Furthermore, as V1 is attained earlier on the runway, lift-off takes place further from the obstacles, thus increasing the obstacle clearance.Margin at V1OAT = 10°C ASS. TEMP = 30°Cweight is MTOWV1
43 Landing and Go-Around Landing Distance Approach Climb Landing Climb Procedure Design Missed Approach GradientJAR(a) The horizontal distance necessary to land and to come to a complete stop from a point 50 ft above the landing surface must be determined (for standard temperatures, at each weight, altitude and wind within the operational limits established by the applicant for the aeroplane) as follows:(1) The aeroplane must be in the landing configuration.(2) A stabilised approach, with a calibrated airspeed of VREF must be maintained down to the 50 ft height. VREF may not be less than--(i) 1·23 VSR0;(ii) VMCL established under JAR (f); and(iii) A speed that provides the manoeuvring capability specified in JAR (g).(3) Changes in configuration, power or thrust, and speed, must be made in accordance with the established procedures for service operation. (See ACJ (a)(3).)(4) The landing must be made without excessive vertical acceleration, tendency to bounce, nose over or ground loop.(5) The landings may not require exceptional piloting skill or alertness.(b) The landing distance must be determined on a level, smooth, dry, hard-surfaced runway. (See ACJ (b).) In addition--(1) The pressures on the wheel braking systems may not exceed those specified by the brake manufacturer;(2) The brakes may not be used so as to cause excessive wear of brakes or tyres (see ACJ (b)(2)); and(3) Means other than wheel brakes may be used if that means--(i) Is safe and reliable;(ii) Is used so that consistent results can be expected in service; and(iii) Is such that exceptional skill is not required to control the aeroplane.(c) Not required for JAR-25.(d) Not required for JAR-25.(e) The landing distance data must include correction factors for not more than 50% of the nominal wind components along the landing path opposite to the direction of landing, and not less than 150% of the nominal wind components long the landing path in the direction of landing.(f) If any device is used that depends on the operation of any engine, and if the landing distance would be noticeably increased when a landing is made with that engine inoperative, the landing distance must be determined with that engine inoperative unless the use of compensating means will result in a landing distance not more than that with each engine operating.
44 Landing DistanceJAR 25 defines the landing distance as the horizontal distance required to bring the airplane to a standstill from a point 50 ft above the Runway Threshold.They are determined for Standard Temperatures as a function of:WeightAltitudeWind (50% Headwind and 150% Tailwind)Configuration (Flaps, Manual/Auto-Speedbrakes, Brakes)They are determined from a Height of 50 ft at VREF on a Dry (or Wet), Smooth Runway using Max Brakes, full Antiskid and Speedbrakes but No ReversersVREF = minimum 1.23 VSR0
45 Landing DistanceBoeing describes the braking technique as “Aggressive”. The Brakes are fully depressed at touchdownRunway Slope is NOT accounted forNon standard temperatures are NOT accounted forApproach speed Additives are NOT accounted forThese are considered to be covered by the extra margins used to define certified landing distances
48 Approach ClimbAircrafts are certified to conduct a missed approach and satisfy a Gradient of 2.1% - GROSSThe configuration is: One Engine Inoperative Gear Up Go Around Flaps (15 on 737) G/A ThrustSpeed must be 1.4 VSR(Strictly speaking, the Flap Setting must be an intermediate flap setting corresponding to normal procedures whose stalling speed is not more than 110% of the final flap stalling speed)JAR (d)Approach. In a configuration corresponding to the normal all-engines-operating procedure in which VSR for this configuration does not exceed 110% of the VSR for the related all-engines-operating landing configuration, the steady gradient of climb may not be less than 2·1 % for two-engined aeroplanes, 2·4% for three-engined aeroplanes and 2·7% for four-engined aeroplanes, with--(1) The critical engine inoperative, the remaining engines at the go-around power or thrust setting;(2) The maximum landing weight;(3) A climb speed established in connection with normal landing procedures, but not more than 1·4 VSR; and(4) Landing gear retracted.
50 Landing ClimbAircrafts are certified to conduct a missed approach and satisfy a Gradient of 3.2% - GROSSThe configuration is: All Engines Operating Gear Down Landing Flaps (30 or 40 on 737) G/A ThrustThe speed must be 1.13 VSR and VMCLIt is also a requirement that full G/A thrust must be available within 8 seconds of the thrust levers forward from idleJAR Landing climb: all engines operatingIn the landing configuration, the steady gradient of climb may not be less than 3·2%, with--(a) The engines at the power or thrust that is available 8 seconds after initiation of movement of the power or thrust controls from the minimum [flight idle to the go-around power or thrust] setting (see ACJ (a)); and(b) A climb speed which is--(1) Not less than--(i) 1·08 VSR for aeroplanes with four engines on which the application of power results in a significant reduction in stall speed; or(ii) 1·13 VSR for all other aeroplanes;(2) Not less than VMCL ; and(3) Not greater than VREF.VMCL, the minimum control speed during approach and landing with all engines operating, is the calibrated airspeed at which, when the critical engine is suddenly made inoperative, it is possible to maintain control of the aeroplane with that engine still inoperative, and maintain straight flight with an angle of bank of not more than 5°.
51 JAA Low Visibility Climb An Aircraft must be certified to conduct a missed approach and satisfy a Gradient of 2.5% - GROSS or the published Missed Approach GradientThe configuration is: One Engine Inoperative Gear Up Go Around Flap (15 on a 737) G/A ThrustThis is only applicable if Low Visibility Procedures will be conducted with a DH of below 200 Ft or No DH
52 Max Landing WeightThe maximum landing weight for dispatch is the least of the:Field Limited Landing WeightApproach Climb Limited Landing WeightLanding Climb Limited Landing WeightJAA LVP G/A Climb Gradient Limited Landing WeightStructural Limited Landing Weight
53 Procedure Missed Approach Gradient 3.9% GROSS+ 0.6%MAP+ 0.8%98 Ft2.5% NETProcedures are designed to satisfy a Missed Approach Gradient of 2.5 % NETIf we add the Nettage factor of 0.8% to find the Gross Gradient we see that this becomes 3.3%If the procedure requires Turns then a further 0.6% must be added to take into account the performance lost in a 15º Bank Turn. We now require a Gross Gradient of 3.9%This does not take Tailwinds into account
54 Procedure Missed Approach Gradient Some specific procedures require a Net gradient of more than 2.5%. This will be indicated on the Chart
55 Procedure Missed Approach Gradient A conflict exists between JAR 25 and ICAOJAR 25 requires a Approach Climb Gradient of 2.1% Gross and a Landing Climb gradient of 3.2% GrossICAO requires a missed approach procedure gradient of at least 2.5% Net which may require at least 3.9% GrossAnd Tailwind has not been accounted for
56 Procedure Missed Approach Gradient …but what if you lose one on the go-around from a normal approach ?...The case of an engine failure during Go-Around is not considered as this is deemed a remote possibility!!!
57 Landing Performance Data Which is the more restrictive?DFnBoth Engines5 xThrust Available on 1 Engine75%EASWith Twins, the Approach Climb will be the most limiting
58 Procedure Missed Approach Gradient Remember the Go-Around procedure is designed for 1 engine inopWith all engines operating, this should not be a problemWith 1 engine inop, generally this should not be a problemIf the Go Around procedure is very different to EOP procedure, then it may be prudent to use this procedureSome airfields may specify this if terrain clearance is critical