AWO.B.CATIII.101 CS AWO.B.CATIII.101 Applicability

This section is applicable to aeroplanes for which certification is sought to allow the performance of approaches with DHs below 30 m (100 ft) or with no DH -Category III operations, using a precision approach system as defined in ICAO Annex 10.

The criteria are divided, where necessary, into those applicable to the following types of operation:

- (1) DHs below 30 m (100 ft) but not less than 15 m (50 ft); - (2) DHs below 15 m (50 ft); and - (3) No DH.

(See AMC AWO.B.CATIII.101(a))

[Issue: CS-AWO/2]

AMC AWO.B.CATIII.101(a) Applicability and terminology

ED Decision 2022/007/R

A precision approach system, as defined in ICAO Annex 10, is considered an xLS (ILS, MLS or GLS) which has outputs that indicate the magnitude and sense of deviation from a preset azimuth and elevation angle giving operational characteristics equivalent to those of a conventional ILS.

An aeroplane with a basic airworthiness approval for IFR operations is eligible to perform xLS precision approaches down to a DH of 60 m (200 ft), assuming that the necessary xLS receiver(s) and instruments and their installation have been approved. The supplementary airworthiness criteria for aeroplanes to perform precision approaches down to a DH below 60 m (200 ft) and down to 30 m (100 ft) are contained in Subpart B Section 3.

The purpose of this Section is to specify the supplementary airworthiness criteria for aeroplanes to perform precision approaches with DHs below 30 m (100 ft) or with no DH.

This material may not be appropriate to precision approach aids other than xLS. It should be noted that when other guidance information is used to supplement the xLS (e.g. inertial navigation systems), some reduction may be acceptable in the standard of xLS ground facility indicated below.

Terminology

- (a) The term 'landing system' used here refers only to the airborne system. It includes the equipment listed in CS AWO.B.CATIII.113, and also all related sensors, instruments and power supplies. - (b) 'Automatic landing system': the airborne equ ipment which provides automatic control of the aeroplane during approach and landing. - (c) 'Fail -passive automatic landing system': an automatic landing system is fail -passive if, in the event of a failure, there is no significant out-of-trim condition or deviation of the flight path or attitude but the landing is not completed automatically. - (d) For a fail-passive automatic landing system, the pilot assumes control of the aircraft following a failure.

The following are typical arrangements:

- (1) A monitored automatic pilot in which automatic monitors will provide the necessary failure detection and protection. - (2) Two automatic pilots with automatic comparison to provide the necessary failure detection and protection.

(e)'Super fail -passive automatic landin g system': an automatic landing system which meets the requirements of point (c) but has additional features such as automatic align, roll-out and go-around modes which, along with other aircraft characteristics defined under CS AWO.B.CATIII.113(b)(2), permit operations in lower RVRs than less sophisticated fail-passive landing systems.

(f)'Fail -operational automatic landing system': an automatic landing system is fail -operational if, in the event of a failure, the approach, flare and landing can be completed by the remaining part of the automatic system.

In the event of a failure, the automatic landing system will operate as a fail-passive system.

The following are typical arrangements:

- (1) Two monitored automatic pilots, one remaining operative following a failure. - (2) Three automatic pilots, two remaining operative (to permit comparison and provide necessary failure detection and protection) following a failure.

(g)'Fail -operational hybrid landing syste m': a system which consists of a primary fail -passive automatic landing system and a secondary independent guidance system enabling the pilot to complete a landing manually following a failure of the primary system.

A typical secondary independent guidance system consists of a monitored HUD providing guidance which normally takes the form of command information, but it may alternatively be situation (or deviation) information.

- (h) The alert height is a specified radio height, based on the characteristics of the aeroplane and its fail-operational landing system. In operational use, if a failure occurred above the alert height in one of the required redundant operational systems in the aeroplane (including, where appropriate, ground-roll guidance and the reversionary mode in a hybrid system), the approach would be discontinued and a go-around executed unless reversion to a higher DH is possible. If

Easy Access Rules for All-Weather Operations (CS-AWO)

SUBPART B -APPROACH AND LANDING SECTION 4 -AIRWORTHINESS CERTIFICATION OF AEROPLANES FOR OPERATIONS WITH DECISION HEIGHTS (DHs) BELOW 30 M (100 FT) OR NO DECISION HEIGHT (DH) -CATEGORY III (CAT III) OPERATIONS

a failure in one of the required redundant operational systems occurred below the alert height, it would be ignored and the approach continued.

- (i) DH is the wheel height above the runway elevation by which a go-around must be initiated unless adequate visual reference has been established and the aircraft position and approach path have been assessed as satisfactory to continue the approach and landing safely.

Where 'DH' is used in this document, it means the minimum DH determined in the airworthiness certification.

- (j) A go-around is the transition from an approach to a stabilised climb. - (k) Head-up display landing system (HUDLS)

The term 'HUDLS' refers to the total airborne system which provides head -up guidance to the pilot during the approach, landing or go-around. It includes all the sensors, computers, power supplies, indications and controls. Typically, a HUDLS is used for primary approach guidance for DHs down to 15 m (50 ft).

The terms ' localiser ' and ' glide path ' have been retained for use with either ILS, MLS or GLS.

Cross reference is made in this Section to AMC AWO.A.ALS.110 which provides guidance on controls, indicators and alerts associated with installations incorporating more than one type of approach system (e.g. ILS and MLS and/or GLS).

Characteristics of the types of operation

Additional and more detailed information regarding the characteristics of the types of operation is provided below.

- (a) DH below 30 m (100 ft) but not less than 15 m (50 ft)

The RVR required by a pilot to make the decision to land from a DH below 30 m (100 ft) is less than the RVR required for a DH at 30 m (100 ft). Furthermore, the time from the DH to the start of the flare manoeuvre will be less.

Consequently, in order to achieve the desired success rate and to preserve the safety level, it has been considered necessary that the aeroplane be fitted with an automatic landing system or a head-up landing guidance system. Use of such systems also ensures that the aeroplane is within the obstacle-free zone specified in ICAO Annex 14 during approach and any go-around so that there is no need to take obstacle clearance into account in determining the DH. The RVR limit is set by the responsible national authority in accordance with applicable operating regulations and provides an assessment of the visibility conditions at and below the DH so that, if either the landing system or the xLS signal-in-space fails when the aeroplane is below the DH, the pilot can carry out a manual landing with an acceptable safety level.

The ground guidance system is either:

- (1) a Facility Performance Category III or a Facility Performance Category II ILS that complies with the Facility Performance Category III standards of ICAO Annex 10, Chapter 3-1, in respect of all significant performance parameters, at least down to ILS point D, 900 m (3 000 ft) from the runway threshold;

or

Easy Access Rules for All-Weather Operations (CS-AWO)

SUBPART B -APPROACH AND LANDING SECTION 4 -AIRWORTHINESS CERTIFICATION OF AEROPLANES FOR OPERATIONS WITH DECISION HEIGHTS (DHs) BELOW 30 M (100 FT) OR NO DECISION HEIGHT (DH) -CATEGORY III (CAT III) OPERATIONS

- (2) a Category III MLS that complies with the requirements of ICAO Annex 10, Chapter 3.11; Or - (3) a GAST D GLS that complies with the requirements of ICAO Annex 10

(b)DH below 15 m (50 ft)

Aeroplanes which have a fail-operational landing system, can be certified for operation with a DH below 15 m (50 ft).

In this type of operation, the RVR needs not only to be sufficient for the pilot to make the decision at the DH, but also to be sufficient to enable the pilot to control the aeroplane during the ground roll. The main purpose of the DH is so that the pilot can assess the adequacy of the visibility conditions before touchdown and prepare to take over visual manual control. It is desirable that the DH be late in the flare after the major pitch changes have taken place, and that an automatic go-around system be fitted. There exists an unknown probability that, although the RVR is reported to be adequate, denser patches of fog may lie on the runway, and it is thought prudent to add a margin to the bare minimum required to control the ground roll. The RVR limit is set by the responsible national authority in accordance with the applicable operating regulations.

The ground guidance system (xLS) is as described in point (a), and, additionally, comply with a continuity of service objective (failure survival capability) of 1 -(2 x 10 -6 ). It is assumed that the pilot is promptly notified by air traffic control (ATC) of a failure or degradation of the required ground equipment (e.g. loss of the stand-by xLS transmitter).

- (c) No DH

An aeroplane with a fail-operational landing system with automatic ground-roll control (or ground-roll guidance) may be certified for operation without a DH (operations when the pilot is not required to make a decision described in the definition of DH). Any required RVR limit is set by the responsible national authority in accordance with the applicable operating regulations.

In these visibility conditions, the pilot is likely to brake hard during the ground roll and, therefore, an anti-skid braking system is considered essential. Distance and ground speed indications and automatic braking would obviously be useful, but are not considered essential and are not required.

The ground guidance system (Facility Performance Category III ILS, Category III MLS or GAST D GLS) complies with the Standards of ICAO Annex 10 and, additionally, complies with an integrity objective of 1 -(0.5 x 10 -9 ) ) and an ILS/MLS continuity of service objective of 1 -(2 × 10 -6 ) or a GLS continuity of service objective as stated in ICAO Annex 10, Appendix B, paragraph 3.6.7.1.3.2.

[Issue: CS-AWO/2]