How to assess and report the runway in GRF.

Oct 7, 2020 | Blog

In the previous post , we discussed the Global Reporting Format (GRF). GRF is a standardized language reporting format for runways surface conditions around the globe. In GRF regulations, runway condition code assessment should be based upon trained inspectors’ judgment about the airplane performance in specific conditions. This means that runway inspectors should be aware and deeply understand the runway condition and the aircraft performance. In this post, we go into the runway condition assessment and reporting in GRF.

How to assess runway conditions in GRF?

In GRF regulations, the inspector has to take into account several inputs when he/she is assessing the overall condition of the runway. The five different input channels in runway assessment are described below.

Visual Observation: The visual inspection and the visual observation of the runway.
Shoe Tactile Test: The tactile test by stopping the inspection vehicles and opening the door to be able to test how slippery the runway is.
Car Behaviour: To feel the real physics between the tire and the runway by switching off ABS and all vehicle electronics control. However, GRF regulations do not set any specific requirements regarding the car equipment, e.g. the automatic braking system or vehicle control electronics.
Airplane Behaviour: To assess how the aircraft behaves by taking into account the pilot reports, the special air report called AIREP, in the global reporting format. It is quite clear that runway inspector is unable to assess how the aircraft behaves, that is the pilots’ job. However, the inspector should take into account the report in the global reporting format.
Friction Measurement: The friction measurement as the only objective measurement regarding the slipperiness of the runway.

All these five channels should be considered in the runway assessment. Depending on the total assessment, the inspector should use the Runway condition assessment matrix (RCAM) and make a conclusion that which of the runway surface description boxes of RCAM would be selected. You can read more about RCAM here. For each runway surface description, there is a respective figure in the table, a one-digit number describing how slippery the runway is. This number is called the runway condition code. The pilot’s reports are then assessed or included in the same RCAM table. This table states for the pilot how should they convert an aircraft behaviour in a certain runway condition code number. The runway inspector can use this same aircraft behaviour column in the RCAM table as guidance to test the “Car behaviour” on the runway.
These five input channels combined with the RCAM table are called the global reporting format. This is the system to assess and report runways condition in the future.

How is the flow of runway condition assessment report from inspector to air traffic controllers and pilots?

When runway inspection is done and the friction is measured, this information is passed on through Aeronautical Fixed Telecommunication Network (AFTN). AFTN is a dedicated aviation network, where NOTAM-, SNOWTAM- and ATIS messages are passed for pilots and air traffic control. When a runway condition report is done and the report is published in the AFTN, SNOWTAM and ATIS are passed on through the network, and they will be available in the briefing, in the tower control, and for the pilots.

In GRF, dry and wet runway conditions are the responsibility of the air traffic controller, and conditions worse than wet runway should be published in SNOWTAM. Nevertheless, it is never wrong to publish a SNOWTAM on a wet runway or even a dry runway. When pilots are doing the pre-flight briefing and planning the flight, they are able to see the SNOWTAM message. It is crucial to know that when the runway condition report is done and published in the AFTN network, the SNOWTAM will be in force in the AFTN network for 8 hours. After 8 hours the SNOWTAM will be automatically deleted and it is no longer available for the air traffic controllers or the pilots. If the pilots do not have SNOWTAM available, the pilots will assume that the runway condition will be wet or dry depending on the prevailing weather conditions on the departing airport or at the destination airport. This assumption is made by the pilots also during winter seasons. It is important to point out that the GRF is a year-round system, so SNOWTAM can be and should be published in certain conditions also during the summer season. You can read more about this in future blog posts.

How important is the inspector’s responsibility in GRF?

GRF aims to avoid or decrease accidents related to slipperiness. However, the implementation of GRF heavily depends on trained runway inspectors. When the runway inspector is making the decision to select which box on the RCAM table, the assessment is in principal done based on the contaminant type, its depth, temperature, and coverage percentage. The runway condition code range is from zero which represents no operation to six which represents dry runway. The runway inspector’s responsibility in GRF reporting is significantly increasing compared to the previous reporting since runway condition code zero represents runway conditions where traffic will be suspended on the respective runway. In conclusion, it is up to the runway inspector to decide whether the runway is in use or not.

Check here if you have done all the necessary preparations for GRF.

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