All Weather Operations

Introduction

In order to meet the requirements of the travelling public and freight operations, modern aeroplanes are required to be capable of operating in weather conditions that 25 years ago would not have been possible. The ability to accurately assess and forecast the weather conditions for the aerodromes to be used and the availability of high precision electronic systems capable of providing extremely accurate guidance in both azimuth and elevation, make present day commercial aviation virtually oblivious to the weather.

Whilst it would appear to be technically possible to carry out a completely blind take-off and landing, other considerations need to be taken into account. For instance, it is no good being able to land an aeroplane with zero visibility if the pilot then cannot safely manoeuvre the aeroplane off the runway to the parking stand! Also, not all aerodromes have the same high degree of sophistication with respect to facilities as say London Heathrow. In order to create a framework within which operations specifically in poor visibility can safely be conducted, EUOPS 1 specifies criteria for Low Visibility Operations with respect to take-off and landing. The criteria is explained and detailed in this chapter.

Aerodrome Operating Minima: Operator’s Responsibility

An operator shall establish, for each aerodrome planned to be used, aerodrome operating minima that are not lower than the values given in EU-OPS 1. These are reproduced in this chapter and are required learning. The method of determination of the minima must be acceptable to the Authority. The minima shall not be lower than any that may be established for aerodromes by the State in which the aerodrome is located, except when specifically approved by that State. The use of head-up display (HUD), head-up display landing system (HUDLS) or enhanced vision system (EVS) may allow operations with lower visibilities than normally associated with the aerodrome operating minima (AOM).

Note: The above paragraph does not prohibit in-flight calculation of minima for a non-planned alternate aerodrome if carried out in accordance with an accepted method.

In establishing the aerodrome operating minima which will apply to any particular operation, an operator must take full account of:

•The type, performance and handling characteristics of the aeroplane.

•The composition of the flight crew, their competence and experience.

•The dimensions and characteristics of the runways which may be selected for use.

•The adequacy and performance of the available visual and non-visual ground aids.

•The equipment available on the aeroplane for the purpose of navigation and/or control of the flight path, as appropriate, during the take-off, the approach, the flare, the landing, roll-out and the missed approach.

•The obstacles in the approach, missed approach and the climb-out areas required for the execution of contingency procedures and necessary clearance.

•The obstacle clearance altitude/height for the instrument approach procedures.

•The means to determine and report meteorological conditions; and

•The flight technique to be used during the final approach.

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In categorizing aeroplanes for the determination of operating minima, the indicated airspeed at threshold (VAT) is calculated as below. All approaches shall be flown as stabilized approaches (SAp) unless otherwise approved by the Authority for a particular approach to a particular runway. All non-precision approaches shall be flown using the continuous descent final approach (CDFA) technique unless otherwise approved by the Authority for a particular approach to a particular runway.

Classification of Aeroplanes

The criteria taken into consideration for the classification of aeroplanes by categories is the indicated airspeed at threshold (VAT), which is equal to the stalling speed in the landing configuration (VSO) multiplied by 1.3, or the 1g stall speed (VS1g) multiplied by 1.23, at the maximum certified landing mass. If VSO and VS1g are available, the higher resulting VAT shall be used. The aeroplane categories corresponding to VAT values are in the Figure 5.1:

Figure 5.1 Aircraft category

Low Visibility Operations - General Operating Rules

Low visibility operations consist of:

•Manual take-off (with or without electronic guidance or HUDLS/Hybrid HUD/HUDLS).

•Autocoupled approach to below DH, with manual flare, landing and roll-out.

•Autocoupled approach followed by autoflare, autolanding and manual roll-out.

•Autocoupled approach followed by autoflare, autolanding and auto roll-out when the applicable RVR is less than 400 m.

•Approach flown with the use of a HUDLS/Hybrid HUD/HUDLS and/or EVS.

The precise nature and scope of procedures and instructions given depend upon the airborne equipment used and the flight deck procedures followed. An operator must clearly define flight crew member duties during take-off, approach, flare, roll-out and missed approach in the OM. Particular emphasis must be placed on flight crew responsibilities during transition from non-visual conditions to visual conditions, and on the procedures to be used in deteriorating visibility or when failures occur. Special attention must be paid to the distribution of flight deck duties so as to ensure that the workload of the pilot making the decision to land or execute a missed approach enables him to devote himself to supervision and the decision making process.

The detailed operating procedures and instructions must be specified in the OM. The instructions must be compatible with the limitations and mandatory procedures contained in the AFM and cover the following:

•Checks for the satisfactory functioning of equipment both before departure and in flight.

•Effects on minima caused by changes in the status of the ground installations and airborne equipment.

• Procedures for the take-off, approach, flare, landing, roll-out and missed approach.

•Procedures to be followed in the event of failures, warnings to include HUD/HUDLS/EVS and other non-normal situations.

•The minimum visual reference required.

•The importance of correct seating and eye position.

•Action that may be necessary from the deterioration of visual reference.

•The requirement for all height calls below 200 ft to be based on rad alt and for one pilot to continue to monitor the aeroplane instruments until the landing is complete.

•The requirements for the ILS localizer sensitive area to be protected.

•The information used relating to wind velocity; windshear; turbulence; runway contamination and the use of multiple RVR assessments.

•Procedures to be used for

(A)lower than Standard Category I;

(B)other than Standard Category II;

(C)approaches utilizing EVS; and

(D)practice approaches and landing on runways at which the full Category II or Category III aerodrome procedures are not in force.

•Operating limitations resulting from airworthiness certification.

•Information on the maximum deviation allowed from the ILS glide path or localizer; and

•Allocation of crew duties in the carrying out of the procedures above, to allow the Commander to devote himself/herself mainly to supervision and decision making;

An operator shall not conduct Category II and III operations unless:

•Each aeroplane is certificated for operations with DH below 200 ft, or no DH, and equipped in accordance with CS-AWO or an equivalent accepted by the Authority.

•A suitable system for recording approach and/or automatic landing success and failure is established and maintained to monitor the overall safety of the operation.

•The operations are approved by the Authority.

•The flight crew consists of at least two pilots; and

•DH is determined by a radio altimeter.

An operator shall not conduct low visibility take-offs in less than 150 m RVR (Category A B and C aeroplanes) or 200 m (category D) unless approved by the Authority.

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