CS 25.143 General

ED Decision 2020/024/R

(a) (See AMC 25.143(a) and (b)) The aeroplane must be safely controllable and manoeuvrable during:

(1) take-off;

(2) climb;

(3) level flight;

(4) descent;

(5) approach and go-around; and

(6) approach and landing.

(b) (See AMC 25.143(a) and (b)) It must be possible to make a smooth transition from one flight condition to any other flight condition without exceptional piloting skill, alertness, or strength, and without danger of exceeding the aeroplane limit-load factor under any probable operating conditions, including:

(1) The sudden failure of the critical engine; (See AMC 25.143(b)(1).)

(2) For aeroplanes with three or more engines, the sudden failure of the second critical engine when the aeroplane is in the en-route, approach, or landing configuration and is trimmed with the critical engine inoperative; and

(3) Configuration changes, including deployment or retraction of deceleration devices; and

(4) Go-around manoeuvres with all engines operating. The assessment must include, in addition to controllability and manoeuvrability aspects, the flight crew workload and the risk of a somatogravic illusion. (See AMC 25.143(b)(4))

(c) The aeroplane must be shown to be safely controllable and manoeuvrable with the most critical ice accretion(s) appropriate to the phase of flight as defined in appendices C and O, as applicable, in accordance with CS 25.21(g), and with the critical engine inoperative and its propeller (if applicable) in the minimum drag position:

(1) At the minimum V₂ for take-off;

(2) During an approach and go-around; and

(3) During an approach and landing.

(d) The following table prescribes, for conventional wheel type controls, the maximum control forces permitted during the testing required by sub-paragraphs (a) through (c) of this paragraph. (See AMC 25.143(d)):

(e) Approved operating procedures or conventional operating practices must be followed when demonstrating compliance with the control force limitations for short term application that are prescribed in sub-paragraph (d) of this paragraph. The aeroplane must be in trim, or as near to being in trim as practical, in the immediately preceding steady flight condition. For the take-off condition, the aeroplane must be trimmed according to the approved operating procedures.

(f) When demonstrating compliance with the control force limitations for long term application that are prescribed in sub-paragraph (d) of this paragraph, the aeroplane must be in trim, or as near to being in trim as practical.

(g) When manoeuvring at a constant airspeed or Mach number (up to V_FC/M_FC), the stick forces and the gradient of the stick force versus manoeuvring load factor must lie within satisfactory limits. The stick forces must not be so great as to make excessive demands on the pilot’s strength when manoeuvring the aeroplane (see AMC No. 1 to CS 25.143(g)), and must not be so low that the aeroplane can easily be overstressed inadvertently. Changes of gradient that occur with changes of load factor must not cause undue difficulty in maintaining control of the aeroplane, and local gradients must not be so low as to result in a danger of over-controlling. (See AMC No. 2 to CS 25.143(g)).

(h) (See AMC 25.143(h)). The manoeuvring capabilities in a constant speed coordinated turn at forward centre of gravity, as specified in the following table, must be free of stall warning or other characteristics that might interfere with normal manoeuvring.

(1) A combination of weight, altitude and temperature (WAT) such that the thrust or power setting produces the minimum climb gradient specified in CS 25.121 for the flight condition.

(2) Airspeed approved for all-engines-operating initial climb.

(3) That thrust or power setting which, in the event of failure of the critical engine and without any crew action to adjust the thrust or power of the remaining engines, would result in the thrust or power specified for the take-off condition at V₂, or any lesser thrust or power setting that is used for all-engines-operating initial climb procedures.

(i) When demonstrating compliance with CS 25.143 in icing conditions -

(1) Controllability must be demonstrated with the most critical of the ice accretion(s) for the particular phase of flight as defined in Appendices C and O, as applicable, in accordance with CS 25.21(g).

(2) It must be shown that a push force is required throughout a pushover manoeuvre down to a zero g load factor, or the lowest load factor obtainable if limited by elevator power or other design characteristic of the flight control system. It must be possible to promptly recover from the manoeuvre without exceeding a pull control force of 222 N. (50 lbf); and

(3) Any changes in force that the pilot must apply to the pitch control to maintain speed with increasing sideslip angle must be steadily increasing with no force reversals, unless the change in control force is gradual and easily controllable by the pilot without using exceptional piloting skill, alertness, or strength.

(j) For flight in icing conditions before the ice protection system has been activated and is performing its intended function, it must be demonstrated in flight with the most critical of the ice accretion(s) defined in appendix C, part II(e), and Appendix O, part II(d), as applicable, in accordance with CS 25.21(g), that:

(1) The aeroplane is controllable in a pull-up manoeuvre up to 1.5 g load factor; and

(2) There is no pitch control force reversal during a pushover manoeuvre down to 0.5 g load factor.

(k) Side stick controllers

In lieu of the maximum control forces provided in CS 25.143(d) for pitch and roll, and in lieu of specific pitch force requirements of CS 25.145(b) and CS 25.175(d), it must be shown that the temporary and maximum prolonged force levels for side stick controllers are suitable for all expected operating conditions and configurations, whether normal or non-normal.

It must be shown by flight tests that turbulence does not produce unsuitable pilot-in-the-loop control problems when considering precision path control/tasks.

(l) Electronic flight control systems

For electronic flight control systems (EFCS) which embody a normal load factor limiting system and in the absence of aerodynamic limitation (lift capability at maximum angle of attack),

(1) The positive limiting load factor must not be less than:

(i) 2.5 g with the EFCS functioning in its normal mode and with the high-lift devices retracted up to V_MO/M_MO. The positive limiting load factor may be gradually reduced down to 2.25 g above V_MO/M_MO.;

(ii) 2.0 g with the EFCS functioning in its normal mode and with the high-lift devices extended.

(2) The negative limiting load factor must be equal to or more negative than:

(i) -1.0 g with the EFCS functioning in its normal mode and with the high-lift devices retracted;

(ii) 0 g with the EFCS functioning in its normal mode and with the high-lift devices extended.

(3) The maximum reachable positive load factor wings level may be limited by flight control system characteristics or flight envelope protections (other than load factor limitation), provided that:

(i)  the required values are readily achievable in turn, and

(ii) wings level pitch up responsiveness is satisfactory.

(4) The maximum reachable negative load factor may be limited by flight control system characteristics or flight envelope protections (other than load factor limitation), provided that:

(i) pitch down responsiveness is satisfactory, and

(ii) from level flight, 0 g is readily achievable, or, at least, a trajectory change of 5 degrees per second is readily achievable at operational speeds (from V_LS to Max speed – 10 kt. V_LS is the lowest speed that the crew may fly with auto thrust or auto pilot engaged. Max speed – 10 kt) is intended to cover typical margin from V_MO/M_MO to cruise speeds and typical margin from V_FE to standard speed in high-lift configurations.

(5) Compliance demonstrations with the above requirements may be performed without ice accretion on the airframe.

[Amdt 25/3]

[Amdt 25/7]

[Amdt 25/13]

[Amdt 25/15]

[Amdt 25/16]

[Amdt 25/18]

[Amdt 25/21]

[Amdt 25/26]

AMC 25.143(a) and (b) Controllability and Manoeuvrability

ED Decision 2003/2/RM

In showing compliance with the requirements of CS 25.143(a) and (b) account should be taken of aeroelastic effects and structural dynamics (including aeroplane response to rough runways and water waves) which may influence the aeroplane handling qualities in flight and on the surface. The oscillation characteristics of the flightdeck, in likely atmospheric conditions, should be such that there is no reduction in ability to control and manoeuvre the aeroplane safely.

AMC 25.143(b)(1) Control Following Engine Failure

ED Decision 2003/2/RM

1  An acceptable means of showing compliance with CS 25.143(b)(1) is to demonstrate that it is possible to regain full control of the aeroplane without attaining a dangerous flight condition in the event of a sudden and complete failure of the critical engine in the following conditions:

a.  At each take-off flap setting at the lowest speed recommended for initial steady climb with all engines operating after take-off, with –

i. All engines, prior to the critical engine becoming inoperative, at maximum take-off power or thrust;

ii. All propeller controls in the take-off position;

iii. The landing gear retracted;

iv. The aeroplane in trim in the prescribed initial conditions; and

b.  With wing-flaps retracted at a speed of 1.23 V_SR1 with –

i. All engines, prior to the critical engine becoming inoperative, at maximum continuous power or thrust;

ii. All propeller controls in the en-route position;

iii. The landing gear retracted;

iv. The aeroplane in trim in the prescribed initial conditions.

2  The demonstrations should be made with simulated engine failure occurring during straight flight with wings level. In order to allow for likely delay in the initiation of recovery action, no action to recover the aeroplane should be taken for 2 seconds following engine failure. The recovery action should not necessitate movement of the engine, propeller or trimming controls, nor require excessive control forces. The aeroplane will be considered to have reached an unacceptable attitude if a bank angle of 45° is exceeded during recovery.

AMC 25.143(b)(4) Go-around Manoeuvres

ED Decision 2020/024/R

1. Background

When full thrust or power is applied during a go-around, an excessive level of performance (rate of climb, accelerations) may be reached very quickly, and make it difficult for the flight crew to undertake all the actions required during a go-around, especially in an environment that is constrained (due to Air Traffic Control instructions, operational procedures, etc) and rapidly changing.

This level of performance can also generate acceleration levels (in particular, forward linear accelerations) that could lead to spatial disorientation of the flight crew (e.g. a somatogravic illusion), in particular when combined with reduced visibility conditions and a lack of monitoring of primary flight parameters, such as pitch attitude.

Accidents and incidents have occurred during or after go-arounds where somatogravic illusions have led flight crews to make inappropriate nose-down inputs, leading to an aircraft upset, a loss of control or a deviation from the normal go-around flight path, and in some cases, controlled flight into terrain with catastrophic consequences.

Other accidents resulting in loss of control were due to excessive pitch attitudes combined with the flight crew’s inadequate awareness of the situation.

The risk is higher on aeroplanes that have a large operational range of thrust to weight ratios, in particular for twin-engine aeroplanes and those with long-range capabilities.

2. Criteria for assessing the go-around manoeuvre risk with respect to somatogravic illusions and the flight crew workload

2.1 Somatogravic illusions

It is considered that the risk of a somatogravic illusion is high when encountering high longitudinal acceleration or combined high values of pitch attitude (nose-up), pitch rate and longitudinal acceleration, associated with a loss of outside visual references.

2.2 Workload

In order to provide sufficient time to the flight crew to manage its tasks, and therefore keep their workload at a reasonable level, longitudinal acceleration and vertical speed may need to be constrained. The assessment of the workload should be performed considering the basic workload functions described in Appendix D of CS-25.

2.3 Risk assessment and mitigation means

There are no scientifically demonstrated aeroplane performance limits to ensure that the risks of somatogravic illusions and excessive workloads remain at acceptable levels. However, the following criteria should not be exceeded during a recommended go‑around manoeuvre:

—             a pitch rate value of 4 degrees per second,

—             a pitch attitude of 20 degrees nose-up,

—             an energy level corresponding to either:

—             a vertical speed of 3 000 ft/min at constant calibrated airspeed,

—             a climb gradient of 22 % at constant calibrated airspeed, or

—             a level flight longitudinal acceleration capability of 7.8 km/h (4.2 kt) per second.

Note 1: these boundaries should not affect operational performance, as they are considered to be beyond the operational needs for a go-around.

Note 2: the numbers above should not be considered as hard limits, but as a reference only.

Design mitigation means should be put in place in order to avoid exceeding these criteria and reduce the risk at an acceptable level. These means should:

—             provide a robust method to reduce the risk identified, and

—             be used during recommended go-around procedures.

A reduced go-around (RGA) thrust or power function is considered to be an acceptable means of mitigation (refer to Chapter 4 below).

Alternatively, exceeding any one of the above criteria should be duly justified by the applicant and accepted by EASA.

3. Go-around evaluation

Go-around manoeuvres should be performed during flight testing in order to verify, in addition to the controllability and manoeuvrability aspects, that the flight crew workload and the risk of a somatogravic illusion are maintained at an acceptable level (for an acceptable level of risk of a somatogravic illusion, refer to Chapter 2.3 of this AMC). The go-around manoeuvres should be performed with all engines operating (AEO) and for each approved landing configuration as per the recommended AFM go-around procedure:

—             with the most unfavourable, and practicable, combination of centre of gravity position and weight approved for landing,

—             with any practicable combination of flight guidance/autothrust-throttle/autopilot to be approved, including manual,

—             with a level-off altitude 1 000 ft above the go-around initiation altitude.

4. Implementation of a reduced go-around (RGA) thrust or power function

The applicant may provide an RGA thrust or power function for use when the flight crew initiates a go‑around. The function should operate with any practicable combination of the flight guidance/autothrust‑throttle/autopilot modes to be approved for operation, including manual modes.

This function should limit the engine thrust or power applied and maintain the performance of the aeroplane (in particular, its rate of climb) at a level that:

—             is not less than the minimum required performance compatible with the operational needs and the flight crew workload during this phase; and

—             reduces the flight crew’s risk of suffering a somatogravic illusion.

This thrust or power reduction function may be available either through aircraft system automation or manually.

In any case, acceptable procedure(s) should be available in the aeroplane flight manual (AFM), and the recommended go-around procedure should be based on the RGA thrust or power function.

Note: When a reduced go-around thrust or power function is provided, the applicant should still use the most critical thrust or power within the range of available go-around thrust or power when showing compliance with the CS-25 specifications.

4.1 Design target

RGA functions with a design target of a 2 000 ft/min rate of climb capability have been accepted by EASA.

4.2 Cockpit indications and information to the flight crew

In automatic mode, information that thrust or power is reduced in the RGA mode should be indicated to the flight crew.

In manual mode, the thrust level tables should be made available to the flight crew.

4.3 Evaluation

An evaluation of the go-around manoeuvre with the RGA thrust or power function should be conducted following the recommendations of Chapter 3 above.

4.4 Thrust or power mode command

It should be possible for the flight crew, at any time and without any delay, to select and apply the full go‑around thrust or power.

The applicant should provide specific procedures for which full thrust or power may be required, such as wind shear alert procedures, TCAS alert procedures, etc.

4.5 Engine failure during go-around with RGA thrust or power

When an engine failure occurs during a go-around performed with active RGA thrust or power, if the required thrust or power from the remaining engine(s) to achieve an adequate performance level cannot be applied automatically, a warning alert to the flight crew is required to prompt them to take the necessary thrust or power recovery action. For non-moving autothrust-throttle lever designs or designs relying on manual thrust or power setting procedures, compelling flight deck alerts may be acceptable in lieu of automatic thrust or power recovery of the operating engine(s) to permit the use of maximum go-around thrust or power for compliance with CS 25.121 (d).

The procedure for the recovery of the engine thrust or power setting must be demonstrated to be acceptable in terms of the detection of the situation by the pilot and the required actions in a high-workload environment.

The following items should be evaluated:

—             the timeliness of achieving the minimum required performance;

—             flight crew awareness (indications, alerting…);

—             flight crew actions (commands);

—             the flight crew workload in general.

4.6 Performance published in the AFM for RGA thrust or power

The climb performance required by CS 25.119 (in a landing climb, i.e. with all engines operating) should be based on the actual RGA thrust or power available (applied by following the recommended AFM procedure). The climb performance required by CS 25.121 (in an approach climb, i.e. with one engine inoperative) should be based on:

—             either the RGA thrust or power available, if no thrust or power recovery is implemented,

—             or the go-around thrust or power available after the application of the thrust or power recovery action (either automatically, or manually after an alert is triggered). For non-moving autothrust‑throttle lever designs or manual thrust or power setting procedures, compelling flight deck alerts may be acceptable in lieu of automatic thrust or power recovery of the operating engine to permit the use of maximum go-around thrust or power for compliance with CS 25.121(d).

[Amdt 25/21]

[Amdt 25/26]

AMC 25.143(d) Controllability and Manoeuvrability

ED Decision 2007/010/R

1 The maximum forces given in the table in CS 25.143(c) for pitch and roll control for short term application are applicable to manoeuvres in which the control force is only needed for a short period. Where the manoeuvre is such that the pilot will need to use one hand to operate other controls (such as the landing flare or go-around, or during changes of configuration or power resulting in a change of control force that must be trimmed out) the single-handed maximum control forces will be applicable. In other cases (such as take-off rotation, or manoeuvring during en-route flight) the two handed maximum forces will apply.

2 Short term and long term forces should be interpreted as follows:–

Short term forces are the initial stabilised control forces that result from maintaining the intended flight path during configuration changes and normal transitions from one flight condition to another, or from regaining control following a failure. It is assumed that the pilot will take immediate action to reduce or eliminate such forces by re-trimming or changing configuration or flight conditions, and consequently short term forces are not considered to exist for any significant duration. They do not include transient force peaks that may occur during the configuration change, change of flight condition or recovery of control following a failure.

Long term forces are those control forces that result from normal or failure conditions that cannot readily be trimmed out or eliminated.

[Amdt 25/3]

AMC No. 1 to CS 25.143(g) Controllability and Manoeuvrability

ED Decision 2007/010/R

An acceptable means of compliance with the requirement that stick forces may not be excessive when manoeuvring the aeroplane, is to demonstrate that, in a turn for 0·5g incremental normal acceleration (0·3g above 6096 m (20 000 ft)) at speeds up to V_FC/M_FC, the average stick force gradient does not exceed 534 N (120 lbf)/g.

[Amdt 25/3]

AMC No. 2 to CS 25.143(g) Controllability and Manoeuvrability

ED Decision 2007/010/R

1 The objective of CS 25.143(g) is to ensure that the limit strength of any critical component on the aeroplane would not be exceeded in manoeuvring flight. In much of the structure the load sustained in manoeuvring flight can be assumed to be directly proportional to the load factor applied. However, this may not be the case for some parts of the structure, e.g., the tail and rear fuselage. Nevertheless, it is accepted that the aeroplane load factor will be a sufficient guide to the possibility of exceeding limit strength on any critical component if a structural investigation is undertaken whenever the design positive limit manoeuvring load factor is closely approached. If flight testing indicates that the design positive limit manoeuvring load factor could be exceeded in steady manoeuvring flight with a 222 N (50 lbf) stick force, the aeroplane structure should be evaluated for the anticipated load at a 222 N (50 lbf) stick force. The aeroplane will be considered to have been overstressed if limit strength has been exceeded in any critical component. For the purposes of this evaluation, limit strength is defined as the larger of either the limit design loads envelope increased by the available margins of safety, or the ultimate static test strength divided by 1·5.

2 Minimum Stick Force to Reach Limit Strength

2.1 A stick force of at least 222 N (50 lbf) to reach limit strength in steady manoeuvres or wind up turns is considered acceptable to demonstrate adequate minimum force at limit strength in the absence of deterrent buffeting. If heavy buffeting occurs before the limit strength condition is reached, a somewhat lower stick force at limit strength may be acceptable. The acceptability of a stick force of less than 222 N (50 lbf) at the limit strength condition will depend upon the intensity of the buffet, the adequacy of the warning margin (i.e., the load factor increment between the heavy buffet and the limit strength condition) and the stick force characteristics. In determining the limit strength condition for each critical component, the contribution of buffet loads to the overall manoeuvring loads should be taken into account.

2.2 This minimum stick force applies in the en-route configuration with the aeroplane trimmed for straight flight, at all speeds above the minimum speed at which the limit strength condition can be achieved without stalling. No minimum stick force is specified for other configurations, but the requirements of CS 25.143(g) are applicable in these conditions.

3 Stick Force Characteristics

3.1 At all points within the buffet onset boundary determined in accordance with CS 25.251(e), but not including speeds above V_FC/M_FC, the stick force should increase progressively with increasing load factor. Any reduction in stick force gradient with change of load factor should not be so large or abrupt as to impair significantly the ability of the pilot to maintain control over the load factor and pitch attitude of the aeroplane.

3.2 Beyond the buffet onset boundary, hazardous stick force characteristics should not be encountered within the permitted manoeuvring envelope as limited by paragraph 3.3. It should be possible, by use of the primary longitudinal control alone, to pitch the aeroplane rapidly nose down so as to regain the initial trimmed conditions. The stick force characteristics demonstrated should comply with the following:

a. For normal acceleration increments of up to 0·3 g beyond buffet onset, where these can be achieved, local reversal of the stick force gradient may be acceptable provided that any tendency to pitch up is mild and easily controllable.

b. For normal acceleration increments of more than 0·3 g beyond buffet onset, where these can be achieved, more marked reversals of the stick force gradient may be acceptable. It should be possible for any tendency to pitch up to be contained within the allowable manoeuvring limits without applying push forces to the control column and without making a large and rapid forward movement of the control column.

3.3  In flight tests to satisfy paragraph 3.1 and 3.2 the load factor should be increased until either –

a. The level of buffet becomes sufficient to provide a strong and effective deterrent to further increase of load factor; or

b. Further increase of load factor requires a stick force in excess of 667 N (150 lbf) (or in excess of 445 N (100 lbf) when beyond the buffet onset boundary) or is impossible because of the limitations of the control system; or

c. The positive limit manoeuvring load factor established in compliance with CS 25.337(b) is achieved.

4  Negative Load Factors

It is not intended that a detailed flight test assessment of the manoeuvring characteristics under negative load factors should necessarily be made throughout the specified range of conditions. An assessment of the characteristics in the normal flight envelope involving normal accelerations from 1 g to 0 g will normally be sufficient. Stick forces should also be assessed during other required flight testing involving negative load factors. Where these assessments reveal stick force gradients that are unusually low, or that are subject to significant variation, a more detailed assessment, in the most critical of the specified conditions, will be required. This may be based on calculations provided these are supported by adequate flight test or wind tunnel data.

[Amdt 25/3]

AMC 25.143(h) Manoeuvre Capability

ED Decision 2007/010/R

1 As an alternative to a detailed quantitative demonstration and analysis of coordinated turn capabilities, the levels of manoeuvrability free of stall warning required by CS 25.143(h) can normally be assumed where the scheduled operating speeds are not less than –

1.08 V_SW for V₂

1.16 V_SW for V₂ + xx, V_FTO and V_REF

where V_SW is the stall warning speed determined at idle power and at 1g in the same conditions of configuration, weight and centre of gravity, all expressed in CAS. Neverthless, a limited number of turning flight manoeuvres should be conducted to confirm qualitatively that the aeroplane does meet the manoeuvre bank angle objectives (e.g. for an aeroplane with a significant Mach effect on the C_L/α relationship) and does not exhibit other characteristics which might interfere with normal manoeuvring.

2 The effect of thrust or power is normally a function of thrust to weight ratio alone and, therefore, it is acceptable for flight test purposes to use the thrust or power setting that is consistent with a WAT-limited climb gradient at the test conditions of weight, altitude and temperature. However, if the manoeuvre margin to stall warning (or other relevant characteristic that might interfere with normal manoeuvring) is reduced with increasing thrust or power, the critical conditions of both thrust or power and thrust-to-weight ratio must be taken into account when demonstrating the required manoeuvring capabilities.

[Amdt 25/3]

CS 25.145 Longitudinal control

ED Decision 2018/005/R

(a) (See AMC 25.145(a).) It must be possible at any point between the trim speed prescribed in CS 25.103(b)(6) and stall identification (as defined in CS 25.201(d)), to pitch the nose downward so that the acceleration to this selected trim speed is prompt with:

(1) the aeroplane trimmed at the trim speed prescribed in CS 25.103(b)(6);

(2) the most critical landing gear configuration;

(3) the wing-flaps (i) retracted and (ii) extended; and

(4) engine trust or power (i) off and (ii) at go-around setting.

(b) With the landing gear extended, no change in trim control, or exertion of more than 222 N (50 pounds) control force (representative of the maximum short term force that can be applied readily by one hand) may be required for the following manoeuvres:

(1) With power off, wing-flaps retracted, and the aeroplane trimmed at 1·3 V_SR1, extend the wing-flaps as rapidly as possible while maintaining the airspeed at approximately 30% above the reference stall speed existing at each instant throughout the manoeuvre. (See AMC 25.145(b)(1), (b)(2) and (b)(3).)

(2) Repeat sub-paragraph (b)(1) of this paragraph except initially extend the wing-flaps and then retract them as rapidly as possible. (See AMC 25.145(b)(2) and AMC 25.145(b)(1), (b)(2) and (b)(3).)

(3) Repeat sub-paragraph (b)(2) of this paragraph except at the go-around power or thrust setting. (See AMC 25.145(b)(1), (b)(2) and (b)(3).)

(4) With power off, wing-flaps retracted and the aeroplane trimmed at 1·3 V_SR1, rapidly set go-around power or thrust while maintaining the same airspeed.

(5) Repeat sub-paragraph (b)(4) of this paragraph except with wing-flaps extended.

(6) With power off, wing-flaps extended and the aeroplane trimmed at 1·3 V_SR1 obtain and maintain airspeeds between V_SW and either 1·6 V_SR1, or V_FE, whichever is the lower.

(c) It must be possible, without exceptional piloting skill, to prevent loss of altitude when complete retraction of the high lift devices from any position is begun during steady, straight, level flight at 1·08 V_SR1, for propeller powered aeroplanes or 1·13 V_SR1, for turbo-jet powered aeroplanes, with –

(1) Simultaneous movement of the power or thrust controls to the go-around power or thrust setting;

(2) The landing gear extended; and

(3) The critical combinations of landing weights and altitudes.

(d) Revoked

(e) (See AMC 25.145(e).) If gated high-lift device control positions are provided, sub-paragraph (c) of this paragraph applies to retractions of the high-lift devices from any position from the maximum landing position to the first gated position, between gated positions, and from the last gated position to the fully retracted position. The requirements of sub-paragraph (c) of this paragraph also apply to retractions from each approved landing position to the control position(s) associated with the high-lift device configuration(s) used to establish the go-around procedure(s) from that landing position. In addition, the first gated control position from the maximum landing position must correspond with a configuration of the high-lift devices used to establish a go-around procedure from a landing configuration. Each gated control position must require a separate and distinct motion of the control to pass through the gated position and must have features to prevent inadvertent movement of the control through the gated position. It must only be possible to make this separate and distinct motion once the control has reached the gated position.

(f)  It must be possible to maintain adequate longitudinal and speed control under the following conditions without exceptional piloting skill, alertness, or strength, without danger of exceeding the aeroplane limit-load factor and while maintaining an adequate stall margin throughout the manoeuvre:

(1) Starting with the aeroplane in each approved approach and landing configuration, trimmed longitudinally and with the thrust or power setting per CS 25.161(c)(2), perform a go-around, transition to the next flight phase and level off at the desired altitude:

(i)  with all engines operating and the thrust or power controls moved to the go-around power or thrust setting;

(ii)  with the configuration changes, as per the approved operating procedures or conventional operating practices; and

(iii) with any practicable combination of Flight Guidance/Autothrust-throttle/Autopilot to be approved, including manual.

(2)  Reasonably expected variations in service from the established approach, landing and go-around procedures for the operation of the aeroplane must not result in unsafe flight characteristics during the go-around.

[Amdt 25/18]

[Amdt 25/21]

AMC 25.145(a) Longitudinal control - Control near the stall

ED Decision 2018/005/R

1 CS 25.145(a) requires that there be adequate longitudinal control to promptly pitch the aeroplane nose down from at or near the stall to return to the original trim speed. The intent is to ensure sufficient pitch control for a prompt recovery if the aeroplane is inadvertently slowed to the point of the stall. Although this requirement must be met with engine thrust or power off and at go-around setting, there is no intention to require stall demonstrations at engine thrusts or powers above that specified in CS 25.201(a)(2). Instead of performing a full stall at go-around thrust or power setting, compliance may be assessed by demonstrating sufficient static longitudinal stability and nose down control margin when the deceleration is ended at least one second past stall warning during a 0.5 m/s² (one knot per second) deceleration. The static longitudinal stability during the manoeuvre and the nose down control power remaining at the end of the manoeuvre must be sufficient to assure compliance with the requirement.

2 The aeroplane should be trimmed at the speed for each configuration as prescribed in CS 25.103(b)(6). The aeroplane should then be decelerated at 0.5 m/s² (1 knot per second) with wings level. For tests at idle thrust or power, it should be demonstrated that the nose can be pitched down from any speed between the trim speed and the stall. Typically, the most critical point is at the stall when in stall buffet. The rate of speed increase during the recovery should be adequate to promptly return to the trim point. Data from the stall characteristics test can be used to evaluate this capability at the stall. For tests at go-around thrust or power setting, the manoeuvre need not be continued for more than one second beyond the onset of stall warning. However, the static longitudinal stability characteristics during the manoeuvre and the nose down control power remaining at the end of the manoeuvre must be sufficient to assure that a prompt recovery to the trim speed could be attained if the aeroplane is slowed to the point of stall.

3  For aeroplanes with an automatic pitch trim function (either in manual control or automatic mode), the nose-up pitch trim travel should be limited before or at stall warning activation (or stall buffet onset, or before reaching the angle-of-attack (AOA) limit if a high AOA limiting function is installed), in order to prevent an excessive nose-up pitch trim position and ensure that it is possible to command a prompt pitch down of the aeroplane to recover control.

The applicant should demonstrate this feature during flight testing or by using a validated simulator.

Note 1: the behaviour of the automatic pitch trim function in degraded flight control laws should be evaluated under CS 25.1309 and CS 25.671.

Note 2: the applicant may account for certain flight phases where this limit is not appropriate, and provide a rationale that supports these exceptions to EASA for consideration.

[Amdt No: 25/21]

AMC 25.145(b)(2) Longitudinal control

ED Decision 2003/2/RM

Where high lift devices are being retracted and where large and rapid changes in maximum lift occur as a result of movement of high-lift devices, some reduction in the margin above the stall may be accepted.

AMC 25.145(b)(1), (b)(2) and (b)(3) Longitudinal control

ED Decision 2003/2/RM

The presence of gated positions on the flap control does not affect the requirement to demonstrate full flap extensions and retractions without changing the trim control.

AMC 25.145(e) Longitudinal control

ED Decision 2003/2/RM

If gates are provided, CS 25.145(e) requires the first gate from the maximum landing position to be located at a position corresponding to a go-around configuration. If there are multiple go-around configurations, the following criteria should be considered when selecting the location of the gate:

a. The expected relative frequency of use of the available go-around configurations.

b. The effects of selecting the incorrect high-lift device control position.

c. The potential for the pilot to select the incorrect control position, considering the likely situations for use of the different go-around positions.

d. The extent to which the gate(s) aid the pilot in quickly and accurately selecting the correct position of the high-lift devices.

AMC 25.145(f) Longitudinal control – go-around

ED Decision 2018/005/R

1.  CS 25.145(f)(1) requires there to be adequate longitudinal control to promptly pitch the aeroplane (nose down and up) and adequate speed control in order to follow or maintain the targeted trajectory during the complete manoeuvre from any approved approach and landing configuration to a go-around, transition to the next flight phase and level off at the desired altitude.

The objective is to assess, in particular, the combined effects of a thrust or power application and a nose-up trim pitching moment.

The applicant should perform the evaluation throughout the range of thrust-to-weight ratios to be certified. This range should include, in particular, the highest thrust-to-weight ratio for the all-engines-operating condition, with the aeroplane at its minimum landing weight, all engines operating and the thrust or power at the go-around setting.

The evaluation should show adequate:

—             pitch control (i.e. no risk of excessive pitch rate or attitude, maintaining an adequate stall margin throughout the manoeuvre, no excessive overshoot of the level-off altitude), and

—             speed control (i.e. no risk of speed instability or exceedance of VFE with the wing-flaps extended and VLE with the landing gear extended).

Refer also to AMC No. 1 to CS 25.1329, Section 14.1.3.3, which provides guidance related to the demonstration of the flight guidance system go-around mode.

2.  The applicant shall evaluate reasonably expected variations in service from the established approach, landing and go-around procedures and ensure that they do not result in unsafe flight characteristics during a go-around.

It is expected that these variations may include:

a)  non-stabilised speed conditions prior to the initiation of a go-around (e.g. approach speed - 5 kt), and

b)  adverse pitch trim positions:

i)  In manual mode with a manual pitch trim, a pitch trim positioned for the approach or landing configuration, and kept at this position during the go-around phase; and

ii)  in autopilot or manual mode with an automatic pitch trim function: the most adverse position that can be sustained by the autopilot or automatic pitch trim function, limited to the available protecting/limiting features or alert (if credit can be taken for it).

The applicant should perform these demonstrations by conducting go-around manoeuvres in flight or during simulator test programmes.

[Amdt 25/21]

CS 25.147 Directional and lateral control

ED Decision 2017/015/R

(See AMC 25.147)

(a) Directional control; general. (See AMC 25.147(a).) It must be possible, with the wings level, to yaw into the operative engine and to safely make a reasonably sudden change in heading of up to 15° in the direction of the critical inoperative engine. This must be shown at 1·3 V_SR1, for heading changes up to 15° (except that the heading change at which the rudder pedal force is 667 N (150 lbf) need not be exceeded), and with –

(1) The critical engine inoperative and its propeller (if applicable) in the minimum drag position;

(2) The power required for level flight at 1.3 V_SR1, but not more than maximum continuous power;

(3) The most unfavourable centre of gravity;

(4) Landing gear retracted;

(5) Wing-flaps in the approach position; and

(6) Maximum landing weight.

(b) Directional control; aeroplanes with four or more engines. Aeroplanes with four or more engines must meet the requirements of sub-paragraph (a) of this paragraph except that –

(1) The two critical engines must be inoperative with their propellers (if applicable) in the minimum drag position;

(2) Reserved; and

(3) The wing-flaps must be in the most favourable climb position.

(c) Lateral control; general. It must be possible to make 20° banked turns, with and against the inoperative engine, from steady flight at a speed equal to 1·3 V_SR1, with –

(1) The critical engine inoperative and its propeller (if applicable) in the minimum drag position;

(2) The remaining engines at maximum continuous power;

(3) The most unfavourable centre of gravity;

(4) Landing gear both retracted and extended;

(5) Wing-flaps in the most favourable climb position; and

(6) Maximum take-off weight;

(d) Lateral control; roll capability. With the critical engine inoperative, roll response must allow normal manoeuvres. Lateral control must be sufficient, at the speeds likely to be used with one engine inoperative, to provide a roll rate necessary for safety without excessive control forces or travel. (See AMC 25.147(d).)

(e) Lateral control; aeroplanes with four or more engines. Aeroplanes with four or more engines must be able to make 20° banked turns, with and against the inoperative engines, from steady flight at a speed equal to 1·3 V_SR1, with maximum continuous power, and with the aeroplane in the configuration prescribed by sub-paragraph (b) of this paragraph.

(f) Lateral control; all engines operating. With the engines operating, roll response must allow normal manoeuvres (such as recovery from upsets produced by gusts and the initiation of evasive manoeuvres). There must be enough excess lateral control in sideslips (up to sideslip angles that might be required in normal operation), to allow a limited amount of manoeuvring and to correct for gusts. Lateral control must be enough at any speed up to V_FC/M_FC to provide a peak roll rate necessary for safety, without excessive control forces or travel. (See AMC 25.147(f).)

[Amdt 25/18]

[Amdt 25/19]

AMC 25.147(a) Directional control; general

ED Decision 2003/2/RM

The intention of the requirement is that the aircraft can be yawed as prescribed without the need for application of bank angle. Small variations of bank angle that are inevitable in a realistic flight test demonstration are acceptable.

AMC 25.147(d) Lateral control: Roll capability

ED Decision 2003/2/RM

An acceptable method of demonstrating compliance with CS 25.147(d) is as follows:

With the aeroplane in trim, all as nearly as possible,in trim, for straight flight at V₂, establish a steady 30° banked turn. It should be demonstrated that the aeroplane can be rolled to a 30° bank angle in the other direction in not more than 11 seconds. In this demonstration, the rudder may be used to the extent necessary to minimise sideslip. The demonstration should be made in the most adverse direction. The manoeuvre may be unchecked. Care should be taken to prevent excessive sideslip and bank angle during the recovery.

Conditions:  Maximum take-off weight.

Most aft c.g. position.

Wing-flaps in the most critical take-off position.

Landing Gear retracted.

Yaw SAS on, and off, if applicable.

Operating engine(s) at maximum take-off power.

The inoperative engine that would be most critical for controllability, with the propeller (if applicable) feathered.

Note: Normal operation of a yaw stability augmentation system (SAS) should be considered in accordance with normal operating procedures.

AMC 25.147(f) Lateral control: All engines operating

ED Decision 2003/2/RM

An acceptable method of demonstrating that roll response and peak roll rates are adequate for compliance with CS 25.147(f) is as follows:

It should be possible in the conditions specified below to roll the aeroplane from a steady 30° banked turn through an angle of 60° so as to reverse the direction of the turn in not more than 7 seconds. In these demonstrations the rudder may be used to the extent necessary to minimise sideslip. The demonstrations should be made rolling the aeroplane in either direction, and the manoeuvres may be unchecked.

Conditions:

(a) En-route:  Airspeed. All speeds between the minimum value of the scheduled all-engines-operating climb speed and V_MO/M_MO.

Wing-flaps. En-route position(s).

Air Brakes. All permitted settings from Retracted to Extended.

Landing Gear. Retracted.

Power. All engines operating at all powers from flight idle up to maximum continuous power.

Trim. The aeroplane should be in trim from straight flight in these conditions, and the trimming controls should not be moved during the manoeuvre.

(b) Approach:  Airspeed. Either the speed maintained down to the 15 m (50 ft) height in compliance with CS 25.125(a)(2), or the target threshold speed determined in accordance with CS 25.125(c)(2)(i) as appropriate to the method of landing distance determination used.

Wing-flaps. In each landing position.

Air Brakes. In the maximum permitted extended setting.

Landing Gear. Extended.

Power. All engines operating at the power required to give a gradient of descent of 5·0%.

Trim. The aeroplane should be in trim for straight flight in these conditions, and the trimming controls should not be moved during the manoeuvre.

CS 25.149 Minimum control speed

ED Decision 2003/2/RM

(See AMC 25.149)

(a) In establishing the minimum control speeds required by this paragraph, the method used to simulate critical engine failure must represent the most critical mode of powerplant failure with respect to controllability expected in service.

(b) V_MC 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) V_MC may not exceed 1·13 V_SR 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 V_MC);

(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; and

(7) If applicable, the propeller of the inoperative engine –

(i) Windmilling;

(ii) In the most probable position for the specific design of the propeller control; or

(iii) Feathered, if the aeroplane has an automatic feathering device acceptable for showing compliance with the climb requirements of CS 25.121.

(d) The rudder forces required to maintain control at V_MC may not exceed 667 N (150 lbf) nor may it be necessary to reduce power or thrust of the operative engines. During recovery, the aeroplane may not assume any dangerous attitude or require exceptional piloting skill, alertness, or strength to prevent a heading change of more than 20°.

(e) V_MCG, 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, it is possible to maintain control of the aeroplane using the rudder control alone (without the use of nose-wheel steering), as limited by 667 N of force (150 lbf), and the lateral control to the extent of keeping the wings level to enable the take-off to be safely continued using normal piloting skill. In the determination of V_MCG, 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 9.1 m (30 ft) laterally from the centreline at any point. V_MCG 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 AMC 25.149(e).)

(f) (See AMC 25.149(f)) V_MCL, 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°. V^MCL must be established with –

(1) The aeroplane in the most critical configuration (or, at the option of the applicant, each configuration) for approach and landing with all engines operating;

(2) The most unfavourable centre of gravity;

(3) The aeroplane trimmed for approach with all engines operating;

(4) The most unfavourable weight, or, at the option of the applicant, as a function of weight;

(5) For propeller aeroplanes, the propeller of the inoperative engine in the position it achieves without pilot action, assuming the engine fails while at the power or thrust necessary to maintain a 3 degree approach path angle; and

(6) Go-around power or thrust setting on the operating engine(s).

(g) (See AMC 25.149(g)) For aeroplanes with three or more engines, V_MCL-2, the minimum control speed during approach and landing with one critical engine inoperative, is the calibrated airspeed at which, when a second critical engine is suddenly made inoperative, it is possible to maintain control of the aeroplane with both engines still inoperative, and maintain straight flight with an angle of bank of not more than 5°. V_MCL-2 must be established with –

(1) The aeroplane in the most critical configuration (or, at the option of the applicant, each configuration) for approach and landing with one critical engine inoperative;

(2) The most unfavourable centre of gravity;

(3) The aeroplane trimmed for approach with one critical engine inoperative;

(4) The most unfavourable weight, or, at the option of the applicant, as a function of weight;

(5) For propeller aeroplanes, the propeller of the more critical engine in the position it achieves without pilot action, assuming the engine fails while at the power or thrust necessary to maintain a 3 degree approach path angle, and the propeller of the other inoperative engine feathered;

(6) The power or thrust on the operating engine(s) necessary to maintain an approach path angle of 3^o when one critical engine is inoperative; and

(7) The power or thrust on the operating engine(s) rapidly changed, immediately after the second critical engine is made inoperative, from the power or thrust prescribed in sub-paragraph (g)(6) of this paragraph to –

(i) Minimum power or thrust; and

(ii) Go-around power or thrust setting.

(h) In demonstrations of V_MCL and V_MCL-2 –

(1) The rudder force may not exceed 667 N (150 lbf);

(2) The aeroplane may not exhibit hazardous flight characteristics or require exceptional piloting skill, alertness or strength;

(3) Lateral control must be sufficient to roll the aeroplane, from an initial condition of steady straight flight, through an angle of 20° in the direction necessary to initiate a turn away from the inoperative engine(s), in not more than 5 seconds (see AMC 25.149(h)(3)); and

(4) For propeller aeroplanes, hazardous flight characteristics must not be exhibited due to any propeller position achieved when the engine fails or during any likely subsequent movements of the engine or propeller controls (see AMC 25.149(h)(4)).

AMC 25.149 Minimum control speeds

ED Decision 2003/2/RM

1 The determination of the minimum control speed, V_MC, and the variation of V_MC with available thrust, may be made primarily by means of ‘static’ testing, in which the speed of the aeroplane is slowly reduced, with the thrust asymmetry already established, until the speed is reached at which straight flight can no longer be maintained. A small number of ‘dynamic’ tests, in which sudden failure of the critical engine is simulated, should be made in order to check that the V_MCs determined by the static method are valid.

2 When minimum control speed data are expanded for the determination of minimum control speeds (including V_MC, V_MCG and V_MCL) for all ambient conditions, these speeds should be based on the maximum values of thrust which can reasonably be expected from a production engine in service.

The minimum control speeds should not be based on specification thrust, since this thrust represents the minimum thrust as guaranteed by the manufacturer, and the resulting speeds would be unconservative for most cases.

AMC 25.149(e) Minimum control speed

ED Decision 2003/2/RM

During determination of V_MCG, engine failure recognition should be provided by:

a. The pilot feeling a distinct change in the directional tracking characteristics of the aeroplane, or

b. The pilot seeing a directional divergence of the aeroplane with respect to the view outside the aeroplane.

AMC 25.149(f) Minimum Control Speed during Approach and Landing (V_MCL)

ED Decision 2020/024/R

(a) CS 25.149(f) is intended to ensure that the aeroplane is safely controllable following an engine failure during an all-engines-operating approach and landing. From a controllability standpoint, the most critical case usually consists of an engine failing after the power or thrust has been increased to perform a go-around from an all-engines-operating approach.

(b) To determine V_MCL, the flap and trim settings should be appropriate to the approach and landing configurations, the power or thrust on the operating engine(s) should be set to the go-around power or thrust setting, and compliance with all the V_MCL requirements of CS 25.149(f) and (h) must be demonstrated.

(c) At the option of the applicant, a one-engine-inoperative landing minimum control speed, V_{MCL (1 out)}, may be determined in the conditions appropriate to an approach and landing with one engine having failed before the start of the approach. In this case, only those configurations recommended for use during an approach and landing with one engine inoperative need be considered. The propeller of the inoperative engine, if applicable, may be feathered throughout.

The resulting value of V_{MCL (1 out)} may be used in determining the recommended procedures and speeds for a one-engine-inoperative approach and landing.

[Amdt 25/26]

AMC 25.149(g) Minimum Control Speed with Two Inoperative Engines during Approach and Landing (V_MCL-2)

ED Decision 2020/024/R

(a) For aeroplanes with three or more engines, V_MCL-2 is the minimum speed for maintaining safe control during the power or thrust changes that are likely to be made following the failure of a second critical engine during an approach initiated with one engine inoperative.

(b) In accordance with CS 25.149(g)(5) for propeller-driven aeroplanes, the propeller of the engine that is inoperative at the beginning of the approach may be in the feathered position. The propeller of the more critical engine must be in the position it automatically assumes following an engine failure.

(c) Tests should be conducted using either the most critical approved one-engine-inoperative approach or landing configuration (usually the minimum flap deflection), or at the option of the applicant, each of the approved one-engine-inoperative approach and landing configurations. The following demonstrations should be conducted to determine V_MCL-2:

(1) With the power or thrust on the operating engines set to maintain a -3 ° glideslope with one critical engine inoperative, the second critical engine is made inoperative and the remaining operating engine(s) are advanced to the go-around power or thrust setting. The V_MCL-2 speed is established with the flap and trim settings appropriate to the approach and landing configurations, the power or thrust on the operating engine(s) set to the go‑around power or thrust setting, and compliance with all the V_MCL-2 requirements of CS 25.149(g) and (h) must be demonstrated.

(2) With the power or thrust on the operating engines set to maintain a -3 ° glideslope, with one critical engine inoperative:

(i) Set the airspeed at the value determined in paragraph (c)(1) above and, with a zero bank angle, maintain a constant heading using trim to reduce the control force to zero. If full trim is insufficient to reduce the control force to zero, full trim should be used, plus control deflection as required; and

(ii) Make the second critical engine inoperative and retard the remaining operating engine(s) to minimum available power or thrust without changing the directional trim. The V_MCL-2 determined in paragraph (c)(1) is acceptable if a constant heading can be maintained without exceeding a 5 ° bank angle and the limiting conditions of CS 25.149(h).

(iii) Starting from a steady straight flight condition, demonstrate that sufficient lateral control is available at V_MCL-2 to roll the aeroplane through an angle of 20 ° in the direction necessary to initiate a turn away from the inoperative engines in not more than five seconds. This manoeuvre may be flown in a bank-to-bank roll through a wings-level attitude.

(d) At the option of the applicant, a two-engine-inoperative landing minimum control speed, V_{MCL‑2 (2 out)} may be determined in the conditions appropriate to an approach and landing with two engines having failed before the start of the approach. In this case, only those configurations recommended for use during an approach and landing with two engines inoperative need be considered. The propellers of the inoperative engines, if applicable, may be feathered throughout.

The values of V_MCL-2 or V_{MCL-2 (2 out)} should be used as guidance in determining the recommended procedures and speeds for a two-engine inoperative approach and landing.

[Amdt 25/26]

AMC 25.149(h)(3) Minimum control speeds

ED Decision 2003/2/RM

The 20° lateral control demonstration manoeuvre may be flown as a bank-to-bank roll through wings level.

AMC 25.149(h)(4) Minimum control speeds

ED Decision 2003/2/RM

Where an autofeather or other drag limiting system is installed and will be operative at approach power settings, its operation may be assumed in determining the propeller position achieved when the engine fails. Where automatic feathering is not available the effects of subsequent movements of the engine and propeller controls should be considered, including fully closing the power lever of the failed engine in conjunction with maintaining the go-around power setting on the operating engine(s).