Low-Visibility Operations - ATPL 070 — Operational Procedures

Whose minima are they

The foundation was laid in the previous module's flight-preparation lesson and only needs recalling: the operator establishes aerodrome operating minima for each departure, destination and alternate aerodrome planned, to keep the aircraft separated from terrain and obstacles and to mitigate the risk of losing visual references in the visual segment of an instrument approach. The method lives in the operations manual, and the method and any change to it are approved by the competent authority. Two of the method's required elements matter especially here: the conditions in the operator's operations specifications, including any specific approvals for low-visibility operations or operational credits, and any non-standard characteristics of the aerodrome, the procedure or the environment. Minima are never generic; they are this operator, this aircraft, this runway.

The vocabulary of low visibility

Six defined terms carry the whole subject, and the exam quotes them nearly verbatim:

Low-visibility operations (LVOs) — approach or take-off operations on a runway with an RVR less than 550 m or with a DH less than 200 ft; the guidance adds that low-visibility conditions themselves mean an RVR below 550 m.

Low-visibility take-off (LVTO) — a take-off with an RVR less than 550 m.

Low-visibility procedures (LVPs) — procedures applied by an aerodrome to ensure safety during LVOs. They belong to the aerodrome, not the operator; the operator's job is to know whether they are in force.

Circling — the visual phase of a circling approach operation; the circling approach operation itself is a Type A instrument approach that brings the aircraft into position for landing on a runway or FATO not suitably located for a straight-in approach.

Visual approach operation — an approach by an IFR flight in which part or all of the instrument approach procedure is not completed and the approach is executed with visual reference to terrain.

Flight control system — in the low-visibility context, a system that includes an automatic landing system, a hybrid landing system, or both. Its failure manners get the next section to themselves.

The Type A label in the circling definition is the same approach taxonomy the Flight Planning course built: Type A operations have a decision height or minimum descent height of 250 ft or more, Type B below that, with Type B splitting into the CAT I, II and III bands whose headline values, CAT I to a DH of 200 ft with RVR 550 m and CAT II down to 100 ft with RVR 300 m, this module's next lesson will unpack.

Systems that fail politely

What separates the categories of low-visibility landing is not how the automatics work but how they fail. A fail-passive flight control system promises that a failure produces no significant out-of-trim condition and no deviation of flight path or attitude, but the landing is not completed automatically: the pilot assumes control of the aeroplane. A fail-operational system promises more: after a failure below the alert height, a certification height above touchdown, the approach, flare and landing can still be completed automatically, the system simply continuing as a fail-passive system from then on. And a fail-operational hybrid landing system reaches fail-operational status by combination: a primary fail-passive automatic landing system backed by a secondary, independent guidance system that lets the pilot complete the landing manually after a primary failure. The hybrid head-up display landing system, a fail-passive autoland plus an independent HUD, is the worked example the rules themselves name. How an autoland actually flies the flare belongs to the instrumentation course; here the failure manners are the law.

Operations behind the approval stamp

The Air Law course filed low-visibility capability among the Part-SPA specific approvals, and this is where that filing cashes out. The operator shall conduct three families of operation only with the competent authority's approval: take-off operations with visibility conditions below 400 m RVR, instrument approach operations in low-visibility conditions, and operations with operational credits, with one carve-out: EFVS 200 operations need no specific approval. Note the two thresholds standing side by side, because the exam loves the gap between them: an LVTO is defined at any RVR below 550 m, but the approval is only required for take-offs below 400 m. A take-off at 450 m RVR is a low-visibility take-off without being an approval matter.

To earn the approval, the operator shall demonstrate a seven-part case:

Aircraft certification — for low-visibility approaches, for LVTO below an RVR of 125 m, and for operational credits, the aircraft is certified for the intended operation.

Crew competence — the flight crew are competent, and a training and checking programme exists for them and for the personnel involved in flight preparation.

Operating procedures — established for the intended operations.

The MEL — any relevant changes to the minimum equipment list have been made.

The maintenance programme — any relevant changes have been made.

Aerodrome suitability — procedures exist to ensure that only suitable aerodromes and instrument flight procedures are used.

A safety assessment — carried out for the intended operations, with performance indicators established to monitor the level of safety.

The aerodrome's share

The operator shall ensure that only aerodromes, including their instrument flight procedures, that are suitable for the intended operations are used for LVOs and operational credits. The acceptable means of compliance assess suitability as a triad: suitable navigation facilities with their instrument approach procedures, suitable aerodrome operating procedures including LVPs compatible with the intended operation, and suitable runway and runway-environment characteristics and facilities. The assessment itself can be made three ways: from previous operational data, records of approaches already flown there with the same procedures and type; by a desktop assessment comparing aerodrome data, procedures and aircraft capability; or, when neither settles it, by an operational assessment with actual flights.

LVPs are required for low-visibility approach operations and for LVTOs below 400 m RVR. Where an aerodrome runs equivalent procedures under another name, the operator should verify they give an equivalent level of safety and note that clearly in the operations manual, with guidance for the crew on how to establish that they are in effect. And where an ILS signal provides guidance in the lowest visibilities, the LVPs should protect the runway and the ILS-sensitive area, so that taxiing metal cannot bend the beam under a landing aircraft. Which RVR numbers attach to which runway lighting is the next lesson's table.

Training for the fog

The training rule is written as operator duties. The operator shall ensure the flight crew is competent for the intended operations, and that every flight crew member completes training and checking for all types of LVO and operational credit for which approval is held. That training and checking shall include initial and recurrent stages, cover normal, abnormal and emergency procedures, be tailored to the technologies used, and take account of the human-factor risks of the operation. Records are kept, and the training and checking are conducted by appropriately qualified personnel, with flight and simulator instruction in the hands of personnel qualified under Part-FCL.

The guidance adds two sharpenings. Pilots new to the aircraft type are a recognised risk: the operator should assess it and mitigate, and where the mitigation is an increment to the visibility or RVR used for LVOs, that increment is stated in the operations manual. And competence decays, so the acceptable means of compliance set a recency rhythm: at least two approaches flown using the operator's low-visibility procedures within the validity period of each operator proficiency check, at least one more in the lowest approved RVR for each additional piece of equipment approved, two approaches for pilots using HUDLS or an equivalent system to touchdown, and the required number in each capacity for pilots who fly as both pilot flying and pilot monitoring.

Flying the procedure

Before commencing any LVO, the acceptable means of compliance put three satisfactions on the commander: that the status of the visual and non-visual facilities is as required, that LVPs are in effect where the operation needs them, and that the flight crew are appropriately qualified. The operating procedures behind the flight should be consistent with the AFM, appropriate to the technology, explicit about each crew member's duties in each phase, and designed to manage workload while deviating as little as practical from normal operations. Their required content is a list worth reading once in full: equipment checks before departure and in flight, seating and eye position, the determination of minima, the new-commander increment where applicable, the effect of failed or downgraded ground equipment and of aircraft system status on the minima, when LVPs are required, an approaching minima call-out to prevent inadvertent descent below the DA/H, height call-outs below 200 ft based on the radio altimeter, the required visual references, the action when they are lost, and the maximum allowable flight-path deviations with the action when they are exceeded.

For CAT II operations the procedure should put at least two pilots on the flight deck, fly the approach with a certified system, and, when the landing is manual, keep the autopilot engaged until visual reference is achieved. At DH the pilot should distinctly see a segment of at least three consecutive lights, from the approach centre line, touchdown zone, runway centre line or runway edge lights, plus a lateral element of the ground pattern: an approach-lighting crossbar, the landing threshold or a touchdown-zone barrette, unless the operation runs a HUD or equivalent to touchdown. CAT III softens the picture by system class: with fail-passive equipment the same three-light segment applies; with a fail-operational system flown to a DH, one centre-line light suffices; and with no DH, the pilot is not required to see the runway before touchdown at all, a CAT III runway being assumed to support no-DH operations unless the AIP or a NOTAM restricts it.

One piece of guidance echoes a height the previous module made famous, though it is a different provision from the approach ban that shares it: the tables translating failed or downgraded equipment into raised minima are meant for use before flight and en route, not on short final. Past 1,000 ft above the aerodrome, the commander is not expected to consult them; a ground-aid failure announced that late leaves continuing the approach to the commander's discretion, while a failure announced earlier is worked through the tables and may cost the approach.

Minimum equipment and the MEL

Equipment honesty runs through the whole approval. Adapting the minimum equipment list is one of the seven demonstrations the approval rule demands, and the authority checks precisely that: an MEL adopted for the LVOs to be undertaken. In operation, the same honesty is procedural: the equipment checks before departure and in flight, the rule that a change in the status of aircraft systems changes the minima, and the commander's pre-LVO satisfaction that facilities are as required. An aircraft that has quietly lost a capability has quietly lost its minima too.

VFR minima at the small end

The subject's last corner is the fair-weather one. For VFR operations with other-than-complex motor-powered aircraft, the acceptable means of compliance let the operator simply apply the VFR operating minima of Part-SERA, adding conditions in the operations manual where factors demand it: radio coverage, terrain, the nature of the take-off and landing sites, flight conditions and ATS capacity. The SERA values themselves were the Air Law course's: 8 km flight visibility at and above 10,000 ft AMSL and 5 km below, cloud clearance of 1,500 m horizontally and 1,000 ft vertically, and the class F and G relaxation at or below 3,000 ft AMSL or 1,000 ft above terrain: 5 km, clear of cloud, with the surface in sight.