Runway safety, and runway excursions specifically, remain among the International Civil Aviation Organization’s top air navigation safety concerns. But it is continuing to address the associated challenges, as ICAO’s technical officer for aerodromes Joseph Cheong explains to Airside International
According to the Flight Safety Foundation, the third-most common landing excursion risk factor is ineffective braking due to runway contamination. Imperfect runway assessment and reporting methods have contributed to the problem, despite several decades of efforts by states to resolve a long-standing issue: the harmonisation of various friction measuring devices and their linkage to aircraft performance.
Explains Cheong: “ICAO has been faced with the challenge of linking runway surface friction information directly to aircraft performance. While this (data) was helpful for runway maintenance purposes, it could also be misleading to pilots depending on weather conditions and other surface contamination factors. Additionally, many ad hoc initiatives by states, research institutions, regional and international organisations used reporting methods that suffered from accuracy and timeliness shortfalls.”
ICAO’s new globally harmonised Global Reporting Format (GRF) represents a major leap forward in answer to the problem, Cheong considers. Drawing from existing international best practices, it is designed to enable runway surface conditions to be reported in a standardised manner, such that flight crew are able to accurately determine aircraft take-off and landing performance no matter the conditions under which the assessments are generated. The GRF incorporates the potential to communicate actual runway surface conditions to flight crew in real time, and in terms that directly relate to aircraft performance data.
In Spring 2015 the GRF proposal was sent for review and feedback to ICAO’s 191 member states and recognised international organisations – including industry groups representing aircraft manufacturers, airports, airlines, pilots and air traffic control (ATC) associations. The majority of replies received indicated broad support and several states as well as Airports Council International (ACI) applauded the initiative for resolving a long-standing safety issue. They feel the GRF will significantly improve runway safety around the world, Cheong recalls.
Thus, the ICAO Council, at its 207th session in February 2016, adopted a comprehensive package of amendment proposals related to the GRF. First, the Standards and Recommended Practices (SARPs) in Annex 14, Volume I, were amended. These determine that when runways are operational, aerodrome operators will be required to undertake on-site assessments of runway surface conditions whenever water, snow, slush, ice or frost are present.
Operators will then report a Runway Condition Code (known as a RWYCC, ranging from 0 to 6) and a description of the runway surface on the basis of the assessment and with reference to the universally accepted terms and definitions for runway contaminants. The code is based on the effect of the runway conditions on aircraft braking performance.
The report, together with the type, depth and coverage of contaminants, will be considered to be the aerodrome operator’s best assessment of the runway surface condition; however, all other pertinent information may also be taken into consideration.
The RWYCC forms part of a Runway Condition Assessment Matrix (RCAM). The matrix gives flight crews the information they need to assess aircraft take-off and landing performance. The GRF also permits friction measurements to be used as part of the overall runway surface assessment on compacted snow- or ice-covered surfaces, provided that the friction-measuring device meets the standard set or agreed by the state.
Due to drag effects of loose contaminants on friction-measuring devices’ measurement wheels, reporting measurements taken from runway surfaces with contaminants other than compacted snow or ice will not be recommended by ICAO, Cheong informs.
There are detailed provisions in the Procedures for Air Navigation Services – Aerodromes (PANS-Aerodromes) Doc 9981 that supplement the SARPs in Annex 14. They contain procedures on the assignment of the RWYCC in accordance with the RCAM.
To determine if an aircraft can safely land in the conditions present at the airport, flight operators will be governed by international provisions in ICAO Annex 6 Parts I and II, and can use both the matrix information supplied by the airport and the associated manufacturer-provided performance data.
With new and updated Annex 15 provisions associated with the new GRF, varying levels of automation in transmitting runway condition information can be provided by NOTAM (a Notice to Airmen). The methodology requires the use of the specialised SNOWTAM format (which notifies the presence or removal of hazardous conditions such as snow, ice and slush) as opposed to alternative NOTAM formats, and its implementation will require any changes to the automated SNOWTAM templates (used to distribute the information on the NOTAM system) to be timed in concurrence with the information originating from aerodromes using the GRF.
Adequate prior notice must also be provided to NOTAM addressees in order to ensure the updating of automation used to filter and communicate information.
Finally, as part of the comprehensive package of amendments, the ICAO PANS-ATM Doc 4444 will contain provisions that ensure that the implementation of the RWYCC and RCAM concepts are supported by the alignment and addition of air-ground radiotelephony phraseologies, as per the use of the associated terms proposed in Annex 14, Volume I, and other documents.
The amendments become applicable on 5 November 2020 and ICAO states have been encouraged to draw attention to the need for every stakeholder to make the necessary adjustments in their management and operational procedures, including provision of the necessary training programmes prior to implementation.
The establishment of a GRF Implementation Team is also being encouraged by ICAO in order to ensure proper planning and co-ordination at the state and/or regional level, Cheong notes. Suitable guidance will be made available by the association and it has scheduled a number of regional workshops to facilitate implementation.
Further plans
As part of its future efforts, ICAO will continue to monitor emerging technologies and advances that are currently being trialled, Cheong confirms. This will include friction measurement by, and correlation with, aircraft equipment. In addition, with the introduction of new technologies, relevant information will be transmitted instantaneously to flight crews, ATC organisations, airport operators and other relevant parties.
Weaknesses in both the ATIS and ATC systems with respect to transmitting safety-critical information also need to be reviewed in the light of the ICAO Global Aviation Safety Plan (GASP) and Global Air Navigation Plan (GANP), he concludes.
