Runway Visual Range (RVR), Flight Crew Procedures and Low Visibility Taxi
Runway Visual Range (RVR)
CAT II/III operations require rapidly updated and reliable reports of visibility conditions, which a pilot may expect to encounter in touchdown zone and along a runway.
RVR measurements are provided by a system of calibrated transmissometers and account for effects of ambient background light and intensity of runway lights. Transmissometers systems are strategically located to provide RVR measurements associated with three basic portions of the runway:
For CAT II/III Approach TDZ RVR is controlling. TDZ RVR may be temporarily replaced with MID RVR if approved by the state of the aerodrome. RVR may be reported by human observation. If MID RVR is reported and relevant, it shall indicate not less than 75 m (125 m if manual rollout). If END RVR is reported and relevant, it shall indicate not less than 75 m.
On contaminated runways, automatic landing with manual rollout is allowed only if all relevant RVR parts indicate not less than 200 m (and minimum DH 50 feet). Automatic landing with automatic rollout is not allowed on contaminated runways.
RVR is not the Slant Visual Range (SVR). SVR is the range over which a pilot of an aircraft in the final stages of approach or landing can see the markings or the lights as described in RVR definition.
The minimum RVR for particular precision approach CAT II is governed by the DH, aeroplane approach category and the approach lighting and runway lighting/marking available. Unless stated otherwise, OM Part C (approach charts) shows adequate minimum RVR information to the flight crew.
The minimum RVR for particular precision approach CAT III is governed by the DH, aeroplane approach category and the approach lighting and runway lighting/marking available, when applicable. Beside general RVR requirements for CAT III operation, the flight crew shall always check current CAT III minima valid for specific state authorities.
Flight Crew Procedures
Flight Preparation
In addition to normal flight preparation, the following planning and preparation must be performed when LVO are predicted.
Check weather condition on departure aerodrome. If it is below the landing minima, a takeoff alternate should be nominated equal to or better than CAT I minima.
Review NOTAMS to make sure that the destination airport meets visual or non-visual CAT II/III requirements:
Weather information: check that the weather forecast at destination is within airline and crew operating minima. If the forecast is below CAT I minima, verify that alternate weather forecasts are appropriate to the available approach means and at least equal or better than CAT I minima.
Check whether approach can be conducted within the aircraft performance limitations. The higher of Company, Crew Qualification, State or Aircraft certified minima shall be applied.
Fuel planning: additional extra fuel should be considered for possible approach delays.
Low Visibility Taxi
Aircraft Status
Check the aircraft system STATUS page that the required landing capability is available. Although it is not required to check equipment that is not monitored by the system, if any of this equipment is seen inoperative (flag), the landing capability may be reduced.
Weather
Check weather conditions at destination and at alternates. Required RVR values must be available for CAT II/III approach. The selected alternate must have weather conditions equal to or better than CAT I.
Approach Ban
If the reported RVRs are below the applicable minima prior to reaching the OM or equivalent DME distance, then the approach is to be discontinued. If the reported RVRs become lower than the applicable minima after passing the OM or equivalent DME distance, the approach may be continued.
ATC Clearance
Unless LVP are reported active by ATIS or ATC, clearance to carry out CAT II/III approach must be requested from ATC, who will check the status of the ILS and lighting and protect the sensitive areas from incursion by aircraft or vehicles. Such an approach may not be undertaken until the clearance has been received. Before the outer marker or 1000ft (as applicable), the required RVR values should be transmitted by the controller.
Seat Position
Seat position and consequent eye position is very important during low visibility approach and landing. A too low seat adjustment may greatly reduce visual segment. When an eye reference position is lower than intended, already short visual segment is further reduced by cut-off angle of glare shield or nose. Seat shall be correctly adjusted as defined in OM Part B.
Use of Landing Lights
At night in low visibility conditions, landing lights can be detrimental to acquisition of visual references. Reflected light from water droplets or snow may actually reduce visibility. Landing lights should therefore not normally be used in actual CAT ll/III weather conditions.
CAT II/III Approach Briefing
In addition to normal approach briefing items, the following subjects should be covered prior to approach:
CAT II/III operations require rapidly updated and reliable reports of visibility conditions, which a pilot may expect to encounter in touchdown zone and along a runway.
RVR measurements are provided by a system of calibrated transmissometers and account for effects of ambient background light and intensity of runway lights. Transmissometers systems are strategically located to provide RVR measurements associated with three basic portions of the runway:
- Touchdown Zone (TDZ),
- Mid-runway Zone (MID), and
- Rollout (or Stop-end) Zone (END).
For CAT II/III Approach TDZ RVR is controlling. TDZ RVR may be temporarily replaced with MID RVR if approved by the state of the aerodrome. RVR may be reported by human observation. If MID RVR is reported and relevant, it shall indicate not less than 75 m (125 m if manual rollout). If END RVR is reported and relevant, it shall indicate not less than 75 m.
On contaminated runways, automatic landing with manual rollout is allowed only if all relevant RVR parts indicate not less than 200 m (and minimum DH 50 feet). Automatic landing with automatic rollout is not allowed on contaminated runways.
RVR is not the Slant Visual Range (SVR). SVR is the range over which a pilot of an aircraft in the final stages of approach or landing can see the markings or the lights as described in RVR definition.
The minimum RVR for particular precision approach CAT II is governed by the DH, aeroplane approach category and the approach lighting and runway lighting/marking available. Unless stated otherwise, OM Part C (approach charts) shows adequate minimum RVR information to the flight crew.
The minimum RVR for particular precision approach CAT III is governed by the DH, aeroplane approach category and the approach lighting and runway lighting/marking available, when applicable. Beside general RVR requirements for CAT III operation, the flight crew shall always check current CAT III minima valid for specific state authorities.
Flight Crew Procedures
Flight Preparation
In addition to normal flight preparation, the following planning and preparation must be performed when LVO are predicted.
Check weather condition on departure aerodrome. If it is below the landing minima, a takeoff alternate should be nominated equal to or better than CAT I minima.
Review NOTAMS to make sure that the destination airport meets visual or non-visual CAT II/III requirements:
- Runway and approach lighting,
- Radio navaid availability,
- RVR equipment availability, etc.
Weather information: check that the weather forecast at destination is within airline and crew operating minima. If the forecast is below CAT I minima, verify that alternate weather forecasts are appropriate to the available approach means and at least equal or better than CAT I minima.
Check whether approach can be conducted within the aircraft performance limitations. The higher of Company, Crew Qualification, State or Aircraft certified minima shall be applied.
Fuel planning: additional extra fuel should be considered for possible approach delays.
Low Visibility Taxi
- Before taxiing for take-off in low visibility conditions, both pilots should be familiar with CAT II/III holding points for take-off runway, any taxiway routing that may be used and possible Hot Spots (Areas of possible error/conflict with other traffic).
- Close attention should be paid to taxi speed (max 10 pts) and taxi routes. Both pilots should give their undivided attention to taxi phase (“both heads up”).
- Any checklist, clearance or action (i.e. Flight Controls check) should only be done while aeroplane is not moving. •If uncertain about position, stop the aeroplane immediately and ask for ATC assistance or Follow Me.
- Remember that ground equipment, aeroplane wingtips and tails may not be as readily seen as taxiway lights, therefore taxi with utmost caution.
- Surface markings shall be strictly followed. Lighted stop bars must not be crossed. CAT II/III holding points must not be crossed until cleared to enter the runway.
- On entering runway and lining up for take-off, double check runway heading reference and make sure that aeroplane is on runway centreline. This could be verified by markings on runway centreline and/or ILS localiser (if runway is ILS equipped).
Aircraft Status
Check the aircraft system STATUS page that the required landing capability is available. Although it is not required to check equipment that is not monitored by the system, if any of this equipment is seen inoperative (flag), the landing capability may be reduced.
Weather
Check weather conditions at destination and at alternates. Required RVR values must be available for CAT II/III approach. The selected alternate must have weather conditions equal to or better than CAT I.
Approach Ban
If the reported RVRs are below the applicable minima prior to reaching the OM or equivalent DME distance, then the approach is to be discontinued. If the reported RVRs become lower than the applicable minima after passing the OM or equivalent DME distance, the approach may be continued.
ATC Clearance
Unless LVP are reported active by ATIS or ATC, clearance to carry out CAT II/III approach must be requested from ATC, who will check the status of the ILS and lighting and protect the sensitive areas from incursion by aircraft or vehicles. Such an approach may not be undertaken until the clearance has been received. Before the outer marker or 1000ft (as applicable), the required RVR values should be transmitted by the controller.
Seat Position
Seat position and consequent eye position is very important during low visibility approach and landing. A too low seat adjustment may greatly reduce visual segment. When an eye reference position is lower than intended, already short visual segment is further reduced by cut-off angle of glare shield or nose. Seat shall be correctly adjusted as defined in OM Part B.
Use of Landing Lights
At night in low visibility conditions, landing lights can be detrimental to acquisition of visual references. Reflected light from water droplets or snow may actually reduce visibility. Landing lights should therefore not normally be used in actual CAT ll/III weather conditions.
CAT II/III Approach Briefing
In addition to normal approach briefing items, the following subjects should be covered prior to approach:
- Destination and Alternate weather,
- Aeroplane technical status (landing capability),
- Crew LVO operational status,
- State LVO approvals, aerodrome LVO status and restricting effect (if applicable),
- Determination and insertion of DH (or NO DH),
- Brief review of task sharing and callouts,
- Downgrading possibilities above 1000 ft AGL,
- Procedure in case of malfunctions below 1000 ft AGL,
- Go-around procedure, ATC calls,
- Optimum seat position and reminder to set cockpit lights when appropriate,
- Use of Auto brake as required.
Runway Visual Range (RVR), Flight Crew Procedures and Low Visibility Taxi
Reviewed by Aviation Lesson
on
9:27 PM
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Reviewed by Aviation Lesson
on
9:27 PM
Rating:
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