ADR.OPS.B.036 Operations on specially prepared winter runways

PROCEDURES FOR USE OF SAND OR GRIT The aerodrome operator, when using sand or grit, should:

(a)if the runway is contaminated with compacted snow:

(1)use sand or grit at an application rate appropriate to achieve the desired effect;

(2)use sand or grit where the grain passes through a 4.75 mm sieve; and

(3)remove as completely as possible any loose contaminants;

(b)if the runway is contaminated with ice:

(1)remove as completely as possible any loose contaminants;

(2)use sand or grit at an application rate appropriate to achieve the desired effect; when the air temperature is stable and the surface temperature is below freezing, consider using frozen sand or grit; and

(3)use sand or grit where the grain passes through a 4.75 mm sieve;

(c)ensure that sand or grit maintains the required specifications until application.

PROCEDURES FOR USE OF SAND OR GRIT The application rate depends on several parameters including temperature, wind speed, vehicle speed, the quality of the material, wear and tear from operations and local experience. Consideration needs to be given to the application rate in order to achieve the desired effect. Very low application rate may only tolerate a very limited number of operations or pass by the sweeping machines, whereas higher application rates may be detrimental to the effectiveness of the treatment. In order to ensure that the sand or grit is in contact with the aeroplane tyres during operations, the surface needs to be free of any loose contaminants. In practical terms, sand or grit is visible during operations. Light precipitation or drifting snow needs to be removed to ensure the effectiveness of the treatment. The need to ensure that the material maintains the required specification until application requires that actions be taken in order to ensure that no foreign objects are mixed with the sand or grit from origin to the dispenser vehicle, and storage is in a suitable environment to avoid the formation of frozen lumps.

METEOROLOGICAL PARAMETERS In order to ensure the effectiveness of the use of materials, the aerodrome operator should establish limitations and ranges for when the procedures may be applied using the following meteorological parameters:

(a)air temperature;

(b)surface temperature (when available);

(c)dew point; and

(d)wind speed and direction.

MANAGEMENT OF LOOSE SAND OR GRIT Excess sand or grit no longer adhering to the surface can reduce aircraft braking performance and could be ingested by engines. When using sand or grit, it is essential that the aerodrome operator monitors the situation and removes loose sand or grit from the operational surfaces as soon as possible. Excess sand or grit can be efficiently removed by mechanical sweeping and blowing.

ASSESSMENT OF ACHIEVED RESULTS

(a)The procedures should define the operational objectives for specially prepared winter runways.

(b)The aerodrome operator, when operating in accordance with the requirements for specially prepared winter runways, should monitor continuously and assess the achieved results.

(c)In case of deviations from operational objectives when materials are applied, the aerodrome operator should take mitigating actions to correct the achieved results and inform aeroplane operators as necessary.

ASSESSMENT OF ACHIEVED RESULTS The operational objectives are aligned with the need to establish a runway surface at least with friction characteristics commensurate with RWYCC 4. This could mean a need to apply materials (sand, grit or chemicals) and to assess whether frozen sand can be applied. If it is assessed that the treatment (frozen sand or other method) has not achieved the desired results (i.e. at least the equivalent of RWYCC 4), a specially prepared winter runway is reported with the appropriately downgraded RWYCC, and in the RCR free text field, the word ‘DOWNGRADED’ is used. Depending on the actual weather and traffic conditions, the continuous monitoring and assessment of the achieved results may be carried out by the same staff operating the equipment for surface treatment or by staff operating an independent vehicle in contact with the equipment operator.

AEROPLANE DATA The aeroplane data related to stopping performance should:

(a)include a timestamp for each flight and be related to the subject runway;

(b)contain all necessary parameters for the chosen method of analysis, recorded with an appropriate frequency; and

(c)permit the isolation of the effective braking action. If available, braking action information identified by a third party from aeroplane data may be used when it can be related to specific landings on the subject runway.

AEROPLANE DATA ANALYSIS The analysis of aeroplane performance data for the purpose of deducing available braking action usually implies the isolation of the total friction force. Either isolating the friction coefficient or comparing the actual stopping capability with a reference capability permits identification of a RWYCC experienced by the aeroplane. Typically, this requires a technical or simulation model of the aeroplane performance produced by the manufacturer. The analysis may be performed through a third party or through the resources of the aeroplane manufacturer. The aeroplane operator planning to perform operations on a specially prepared winter runway needs to set up the arrangement with the aeroplane manufacturer.

DEMONSTRATION OF CAPABILITY TO ESTABLISH THE RUNWAY SURFACE CONDITION IN ACCORDANCE WITH A GIVEN RUNWAY CONDITION CODE In order to demonstrate the capability to establish the runway surface condition in accordance with a given RWYCC, the aerodrome operator should demonstrate with a statistical level of confidence of 95 per cent that the actual braking action indicated by aeroplane data is consistently the same as or better than that expected for the reported RWYCC.

DEMONSTRATION OF CAPABILITY TO ESTABLISH THE RUNWAY SURFACE CONDITION IN ACCORDANCE WITH A GIVEN RUNWAY CONDITION CODE The statistical level of confidence is established by analysing data obtained from aeroplane operators and data from aerodrome operators. The analysis is done by the aerodrome operator. The experienced RWYCC is compared with the RWYCC reported by the aerodrome operator. An analysis is performed to calculate the statistical level of confidence for the number of landings when the reported RWYCC was deemed the same as or better than the experienced RWYCC. To obtain statistical significance, a representative number of landings on a winter-contaminated surface prepared such as intended to benefit from the improved braking action used in the demonstration should be as large as possible, but not less than 30.

MAINTENANCE PROGRAMME

(a)The maintenance programme should include at least the following equipment:

(1)sand spreaders including heating and pre-wetting equipment; and

(2)chemical spreaders.

(b)The maintenance programme should include regular verification of the accuracy of distribution rates and temperature measurements for material spreaders.

MONITORING PROGRAMME — PERFORMANCE INDICATORS The aerodrome operator should:

(a)establish a system of performance indicators to systematically monitor the effectiveness of the procedures which are applied to support operations on specially prepared winter runways;

(b)record the performance indicators on a monthly basis during the winter season for each runway and review them on an annual basis; and

(c)prepare and make available an annual report, which includes comparison with the performance indicators of at least the previous 3 years.

MONITORING PROGRAMME — PERFORMANCE INDICATORS The following performance indicators may be used in order to monitor the success in correctly assessing and reporting the runway surface condition:

(a)Proportion of landings on reported RWYCC 4 versus total number of landings on specially prepared winter runways. The indicator aims to measure the frequency of operations on specially prepared winter runways where no downgrade has been used;

(b)Proportion of landings identified under (a) where the braking action computed based on aeroplane data was one RWYCC worse than the RCRs issued by the aerodrome operator;

(c)Proportion of landings identified under (a) where the braking action computed based on aeroplane data was two RWYCCs worse than the RCRs issued by the aerodrome operator.

(d)Number of movements on a contaminated runway (RWYCC 1–4) per total number of movements. This number provides an indication of the exposure of the aerodrome to winter conditions. Information concerning the contamination of the runway can be derived from the RCRs. The indicators mentioned in (a), (b) and (c) provide information concerning the quality of the runway surface condition assessment. Performance indicators should be recorded on a monthly basis.