Q: What Australian requirements dictate that an airport has a programme in place to determine runway surface friction? A: All aerodrome operators are required to maintain runways with sealed, asphalt or concrete surfaces, in accordance with the surface texture standards specified in MOS 139. "An aerodrome technical inspection of runway surfaces is required to confirm that the texture standard is being met. Validation is best carried out by the use of approved Continuous Friction Measuring Equipment (CFME)." In addition, from January 2006, designated international aerodromes with runways serving Code 4 jet aeroplanes, conducting international air transport operations, are required to use an ICAO accepted continuous friction measuring device with self-wetting features to measure the friction level of the runway. "Runways must be evaluated when first constructed or after resurfacing to determine the wet runway surface friction characteristics. Friction measurements must be taken at intervals that will ensure identification of runways in need of maintenance or special surface treatment before the surface conditions deteriorate further. The time interval between measurements will depend on factors such as: aircraft type and frequency of usage, climatic conditions, pavement type, and maintenance requirements." The CFME used by panAero is approved by the FAA, CASA and ICAO and satisfies MOS 139 testing requirements. [Back to Top] 
Q: MOS 139 mandates friction testing at aerodromes serving Code 4 jet aircraft. What is a Code 4 jet aircraft? A: Simplistically, it applies to the Embraer 190 and all Airbus and Boeing aircraft on the Australian register (MOS 139 2.1.6). [Back to Top]
Q: As an airport authority, should we purchase our own approved friction testing equipment (CFME)? A: FAA AC 150/5320-12c gives the following guidance in regard to this question: "At airports where friction tests are performed less frequently than quarterly, and CFME is not used for winter operations, consideration should be given to hiring a qualified contractor to perform tests." [Back to Top]
Q: Please describe the technology utilised in your CFME? A: The panAero Continuous Friction Measuring Equipment (CFME) uses a friction test method operating with a fixed longitudinal slip of 12% on the measuring wheel (skiddometer principle). The advantage of slip measurement is that it can provide a continuous record of the friction value. The trailer axle has a third smaller wheel on an arm which is the measuring wheel. The tyre is of a material, shape and tread which closely resembles that of a normal aircraft tyre. This gives friction readings that correlate well with friction values obtained during normal aircraft operations. The critical vertical load on the measuring wheel is achieved by variable hydraulic pressure automatically controlled by a computer with inputs from a load transducer. The measuring wheel is connected to the rear axle by a chain transmission whose gear ratio provides a constant 12% slip. As the measuring wheel has a smaller diameter than the rear wheel, the chain is tensioned when the vehicle moves. This tension is proportional to runway friction. A torque transducer transforms the tension into analogue signals which are used by the computer to calculate friction values. The panAero CFME is equipped with a self wetting water system for calibration measurement of airport runways and taxiways. The system is adjusted to put out the regulated 1 mm strip water in front of the measuring wheel. [Back to Top]
Q: To what runway surface friction assessment standards do you test to? A: There are three accepted runway surface friction testing standards in use around the world; ICAO, FAA and that from the UK CAA. FAA methodology is the most commonly used however that outlined in the UK CAA CAP 683 is the most comprehensive and provides the best information to the airport authority on actual runway state. panAero normally tests to FAA criteria however we have the capability to test to CAP 683 if requested. [Back to Top]
Q: What is the advantage of testing to the UK CAP 683 standard? A: Testing to CAP 683 standard requires the determination of a continuous 100m rolling friction average which smooths results and potentially, avoids unnecessary runway maintenance. The other advantage is that the standard requires more runs on both sides of the runway than specified by FAA methodology which enables maintenance to be restricted to only those areas in need of rectification. [Back to Top]
Q: If we contract with panAero to do a runway surface friction assessment, what reports will we receive? A: Following initial analysis of the data, a preliminary report will be sent which will indicate that the runway either exceeds Design Objective, exceeds Maintenance Planning Level, falls below Maintenance Planning Level or falls below Minimum Friction Level. This initial document will be followed by a comprehensive report which gives a complete breakdown of actual friction values measured during the various runs along with associated recommendations. [Back to Top]
Q: How many runs are required for a runway surface friction assessment? A: This depends on which testing methodology is requested. FAA methodology requires four runs for runways serving narrow body aircraft and eight for runways serving both narrow and wide body aircraft. UK CAA methodology is more comprehensive with the number of runs depending only on runway width; eight for an 18m runway, 10 for a 23m runway, 10 for a 30m runway, 12 for a 45m runway and 14 for a 60m runway. In addition, we perform a dry check run before and after friction assessment to ensure valid and consistent testing data has been obtained. [Back to Top]
Q: Please explain you pricing structure? A: Pricing for friction testing is based on runway length and width as these have a direct impact on the number of runs required, the time taken to perform the assessment and the number of testing tyres consumed. Additional costs associated with transporting test equipment and personnel to your location will depend upon distance from our home base and if other airports in your area require testing. [Back to Top]
Q: Does panAero do operational or maintenance friction testing? A: We are capable of performing both however as Australia rarely has runways contaminated by ice or snow, operational testing is not normally necessary. [Back to Top]
Q: Can a friction assessment be performed during rain? A: No. Some runways have depressed areas which pond during periods of moderate to heavy rainfall. These areas may exceed the water depth used by the CFME self-wetting system and give erroneous results. This is a limitation of all ICAO approved friction measuring equipment. [Back to Top]
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