CS 25.101 General

The test aeroplane used in the determination of the scheduled performance should be in a condition which, as far as is reasonably possible, is representative of the average new production aeroplane. Where the test aeroplane differs from this standard (e.g. with regard to engine idle thrust settings, flap rigging, etc.) it will be necessary to correct the measured performance for any significant performance effects of such differences.

1.General

CS 25.101(g) requires that procedures must be established for the execution of go-arounds from landing configurations (identified as ‘balked landings’ in this AMC) and from approach configurations (identified as ‘missed approaches’ in this AMC) associated with the conditions prescribed in CS 25.119 and CS 25.121(d). Also, as required by CS 25.1587(b)(4), each AFM must contain the procedures established under CS 25.101(g), including any relevant limitations or information. The landing climb gradient determined under the CS 25.119 conditions, the approach climb gradient determined under the CS 25.121(d) conditions, and the additional operating limitations regarding the maximum landing weight established in accordance with CS 25.1533(a)(2) must be consistent with the established balked landing and missed approach procedures (CS 25.101(g)) provided in the aeroplane flight manual (AFM). In order to demonstrate the acceptability of the recommended missed approach and balked landing procedures, the applicant should conduct demonstrations (by flight test or pilot-in-the-loop simulator tests) to include a one engine inoperative go-around at a weight, altitude, temperature (WAT)-limited or simulated WAT-limited thrust or power condition.

The applicant should conduct the demonstrations at WAT-limited conditions that result in the greatest height loss and/or longest horizontal distance to accelerate to the scheduled approach climb speed. Alternatively, the applicant may conduct testing at simulated WAT-limited conditions (with reduced thrust or power on the operating engine) and use the resulting time delays for each crew action in a subsequent off-line simulation/analysis in accordance with the procedures below. Although compliance with CS 25.101(g) and (h) and CS 25.121(d) is not directly linked with the criteria for the approval of weather minima for approach, the minimum decision height for initiating a go-around is dependent upon the weather minima to be approved. In addition, a steeper climb gradient and the associated lower WAT-limited landing weight may be associated with CAT II operations. As such, if CAT II weather minima approval is expected, the applicant should conduct the go-around demonstration and/or analysis consistent with both CAT I and II operations for the associated decision height and WAT-limited thrust or power condition (or a critical combination thereof).

2.Procedures

The go-around demonstration specified in Chapter 1 of this AMC can be conducted at an altitude above the normal decision height/altitude (for test safety), with the height loss in the manoeuvre used to show that ground contact prior to the runway threshold would not occur if the manoeuvre was initiated at the decision height/altitude. Flight testing, simulation and/or analysis at a range of (WAT limit or simulated WAT limit) conditions throughout the approved envelope should be conducted to assess the height loss relative to the decision height/altitude consistent with the criteria for the weather minima to be approved (or higher as constrained by AFM limitations). At least one flight test or pilot-in-the-loop simulator test should be conducted at a WAT-limited condition to assess the OEI go-around procedure and establish the time delays used for any subsequent analysis/simulation.

In addition, the assessment of the go-around procedure should include consideration of the horizontal distance (based upon the minimum go-around trajectory) needed to establish the minimum engine-out climb gradient required by CS 25.121(d) or a steeper gradient as required by specific weather minima operational criteria. It should be shown by flight test, simulation and/or analysis that the aeroplane would remain above the profile illustrated in Figure 1 below when the go-around is evaluated at the critical WAT limit condition (up to the structural maximal landing weight) and flown in accordance with the one-engine-inoperative (OEI) go-around procedure.

This provides a minimum design standard trajectory for a missed approach with one engine inoperative and does not constitute a means to ensure obstacle clearance. It does not preclude additional missed approach procedures that may be developed to satisfy operational requirements, including special or complex missed approach path requirements. The operator should seek approval from their national aviation authority to use the additional procedures and data.

(a)In accordance with CS 25.101(h), the established procedures for executing balked landings and missed approaches must:

(i)be able to be consistently executed in service by crews of average skill,

(ii)use methods or devices that are safe and reliable, and

(iii)include allowance for any time delays in the execution of the procedures that may reasonably be expected in service (including the recovery of full go-around thrust or power if equipped with a reduced go-around (RGA) thrust or power function that requires a manual override), but should not be less than one second between successive flight crew actions, except for movements of the primary flying controls.

(b)The flight test demonstration(s), simulation and/or analysis should be made with:

(i)all engines operating (AEO) and the thrust or power initially set for a 3-degree approach, and the configuration and final approach airspeed consistent with the AEO landing procedure (not more than VREF + 5 kt) in zero wind conditions,

(ii)application of the available go-around thrust or power at the selected go-around height (initially the RGA thrust or power level, if so equipped, followed by either automatic or manual selection of full go-around thrust or power in accordance with the established missed approach and engine failure AFM procedures) with simultaneous failure of the critical engine (or with a simulated engine failure, including the effects on dependent systems), and

(iii)the high-lift system, pitch attitude, engine/propeller controls and airspeed adjusted to achieve the conditions consistent with CS 25.121(d), in accordance with the established missed approach and engine failure AFM procedures. The landing gear should be selected to the ‘up’ position only after a positive rate of climb is achieved. If the use of automatic features (autopilot, auto-throttle, flight director, etc.) is included in the procedure, these features should be considered during the demonstration.

[Figure or form omitted from this preview — available in the Avioverse workspace library.]

Figure 1. Trajectory Assessment for OEI Go-around

Segment A: From the initiation of go-around at the decision height/altitude to the runway threshold – remain above a 1:50 (2.0 %) plane extended to the runway threshold for clearance of airport obstacles.

Segment B: From the runway threshold plus a distance defined by 40 seconds * VT_appr, not more than the distance indicated in the table below – remain above ground height.

Segment C: A straight line from the end of Segment B at ground height with a gradient defined by CS 25.121(d)(1) or a steeper gradient as required by specific weather minima operational criteria, up to a height, H1 – remain above the line.

Where:

VT_appr is the true airspeed for the normal recommended AEO approach speed in zero wind at the flight condition being assessed (not more than VREF + 9.3 km/h (5 kt) CAS).

H1 is the height above the runway elevation where the aeroplane has achieved the approach climb configuration and stabilised on the approach climb speed out of ground effect (1x the wingspan), not less than the height at which the go-around was initiated.

[Amdt 25/13]

[Amdt 25/26]

CS 25.109(a) and (b) require the accelerate-stop distance to include a distance equivalent to 2 seconds at V1 in addition to the demonstrated distance to accelerate to V1 and then bring the aeroplane to a full stop. This additional distance is not intended to allow extra time for making a decision to stop as the aeroplane passes through V1, but is to account for operational variability in the time it takes pilots to accomplish the actions necessary to bring the aeroplane to a stop. It allows for the typical requirement for up to three pilot actions (i.e. brakes – throttles – spoilers) without introducing additional time delays to those demonstrated. If the procedures require more than three pilot actions, an allowance for time delays must be made in the scheduled accelerate-stop distance. These delays, which are applied in addition to the demonstrated delays, are to be 1 second (or 2 seconds if a command to another crew member to take the action is required) for each action beyond the third action. This is illustrated in Figure 1.

[Figure or form omitted from this preview — available in the Avioverse workspace library.]

* 2 sec. where a command to another crew member is required.

* 2 sec. where a command to another crew member is required.

FIGURE 1. ACCELERATE-STOP TIME DELAYS where:–

VEF is the calibrated airspeed selected by the applicant at which the critical engine is assumed to fail. The relationship between VEF and V1 is defined in CS 25.107.

∆tact 1 = the demonstrated time interval between engine failure and activation of the first deceleration device. This time interval is defined as beginning at the instant the critical engine is failed and ending when the pilot recognises and reacts to the engine failure, as indicated by the pilot’s application of the first retarding means during accelerate-stop tests. A sufficient number of demonstrations should be conducted using both applicant and Agency test pilots to assure that the time increment is representative and repeatable. The pilot’s feet should be on the rudder pedals, not the brakes, during the tests. For AFM data expansion purposes, in order to provide a recognition time increment that can be executed consistently in service, this time increment should be equal to the demonstrated time or 1 second, whichever is greater. If the aeroplane incorporates an engine failure warning light, the recognition time includes the time increment necessary for the engine to spool down to the point of warning light activation, plus the time increment from light ‘on’ to pilot action indicating recognition of the engine failure.

∆tact 2 = the demonstrated time interval between activation of the first and second deceleration devices.

∆tact 3 = the demonstrated time interval between activation of the second and third deceleration devices.

∆tact 4→n = the demonstrated time interval between activation of the third and fourth (and any subsequent) deceleration devices. For AFM expansion, a 1-second reaction time delay to account for in-service variations should be added to the demonstrated activation time interval between the third and fourth (and any subsequent) deceleration devices. If a command is required for another crew member to actuate a deceleration device, a 2-second delay, in lieu of the 1-second delay, should be applied for each action. For automatic deceleration devices that are approved for performance credit for AFM data expansion, established systems actuation times determined during certification testing may be used without the application of the additional time delays required by this paragraph.

It is not necessary for all the performance testing on the aircraft to be conducted with fully worn brakes. Sufficient data should be available from aircraft or dynamometer rig tests covering the range of wear and energy levels to enable correction of the flight test results to the 100% worn level. The only aircraft test that should be carried out at a specific brake wear state is the maximum kinetic energy rejected take-off test of CS 25.109(i), for which all brakes should have not more than 10% of the allowable brake wear remaining.