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Low Visibility Procedures
From SKYbrary Wiki
| Article Information | ||
|---|---|---|
| Category: | Weather | 
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| Content source: | SKYbrary | 
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| Content control: | EUROCONTROL | 
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| WX | |
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| Tag(s) | Pilot Briefing |
Contents |
IR-OPS and EU-OPS Definitions
Low visibility procedures (LVP) means procedures applied at an aerodrome for the purpose of ensuring safe operations during lower than standard category I, other than standard category II, category II and III approaches and low visibility take-offs; - IR-OPS Annex I and EU-OPS 1.435
Low visibility take-off (LVTO) means a take-off with an RVR lower than 400 m but not less than 75 m; - IR-OPS Annex I and EU-OPS 1.435
Note that ICAO requires LVP for all departures below 550m RVR, not just LVTO
Description
Low visibility procedures have been devised to allow aircraft to operate safely from and into aerodromes when the weather conditions do not permit normal operations. To this end, they cover all relevant issues relating to surface movement other than aircraft within the designated aircraft manoeuvring area comprehensively.
Hazards
On aerodromes where the ground marking and lighting is adequate, ground traffic at reasonable flow rates can often be sustained safely in reduced visibility. An aeroplane on the ground is at its most vulnerable during the landing and the take-off phases of flight, when the options for avoiding action if an obstruction is encountered may be very limited. The aircraft is likely to be badly damaged or destroyed if it collides, at high speed, with any sizeable object.
Making the necessary transition to visual reference during the final stages of an approach to land in poor visibility is critical and certain requirements must be met to reduce the risk of a Runway Excursion. Low visibility take off also requires careful attention to correct runway alignment before the take off is commenced; an ILS LLZ signal can be used for verification if available. If an RTO is carried out, pilots must maintain awareness of runway length remaining using whatever external visual cues are available; relevant runway lighting, signage or markings may be available.
As visibility deteriorates, the potential for runway incursions by aircraft, vehicles or personnel increases. The risk of inadvertent runway incursion by taxiing aircraft is greatest at aerodromes with complex layouts and multiple runway access points. This risk can only be managed adequately by the application of procedures that provide the pilot with clear, unambiguous guidance on routing and holding points or ground traffic patterns.
The safe operation of airside vehicles depends upon drivers being adequately trained and thoroughly familiar with the aerodrome layout in all visibility conditions and by complying with procedures, signs, signals and ATC instructions. In low visibility conditions, special awareness is required and special procedures, including restrictions on normal access, may be invoked. All of this is an essential product of the Airport Operator SMS
Aerodromes
Aerodromes that wish to continue operating in poor visibility or are available for instrument approaches in conditions of low cloud are required to develop and maintain LVPs.
Aerodromes that provide precision instrument approaches are required to develop and maintain additional procedures that ensure suitable measures are in place to protect the signal produced by the ground based radio navigation equipment.
The point at which LVPs should be implemented will vary from one aerodrome to another depending on local conditions and facilities available. The point at which LVPs are to be implemented must be clearly defined and should be related to a specific RVR or cloud ceiling measurement (e.g. RVR below 550m or cloud ceiling below 200 ft). Aerodromes may define higher values for RVR and ceiling than the ICAO standard depending on local circumstances.
Adequate consideration should be given to the time taken to implement fully all of the measures required to protect operations in low visibility conditions. Provision should also be made for alerting airlines and other organisations with movement area access in good time of the introduction of LVPs. This is particularly important where companies exercise control over their own apron areas and maintenance facilities adjacent to the manoeuvring area.
National authorities offer guide lines on when LVPs should be implemented and when they should cease. A typical example is UK CAP 168: Licensing of Aerodromes, Appendix 2B, which contains much other useful information and advice on the subject. ICAO guidance material on the implementation of LVP is available in ICAO EUR Doc 013 "European Guidance Material On Aerodrome Operations Under Limited Visibility Conditions".
Operators
Low visibility procedures may only be conducted under strict conditions, which are described fully in IR-OPS Subpart E Low Visibility Operations (LVO) and associated Acceptable Means of Compliance and Guidance Material, and EU-OPS 1.440 - EU-OPS 1.460 and relevant appendices. Essentially these concern the following main areas:
- Flight crew constitution, training, qualification and authorisation;
- Aircraft minimum equipment and certification;
- Aerodrome considerations; and,
- Operating procedures.
Related Articles
Further Reading
- ICAO Doc 9476 Manual of Surface Movement and Guidance Control Systems, Chapter 5
- ICAO Doc 9830* Advanced Surface Movement Guidance and Control Systems (A-SMGCS) Manual.
- IR-OPS Subpart E Low Visibility Operations (LVO)
- Acceptable Means of Compliance (AMC) and Guidance Material (GM) to IR-OPS Part-SPA
- EU-OPS 1 Subpart E (All Weather Operations).
- UK CAP 168: Licensing of Aerodromes, Appendix 2B
- European Action Plan for the Prevention of Runway Incursions, All Appendices
- ICAO Doc 9870 App B - Best Practices on the Flight Deck
- European Action Plan for the Prevention of Runway Incursions App D - Flight Crew Best Practices
- ICAO Doc 7013* "European Guidance Material On Aerodrome Operations Under Limited Visibility Conditions
- Note* ICAO Doc 7013 and Doc 9830 are both included in ICAO search: ICAO Doc Search