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Validation of enhanced approach procedures

Photograph aerial view at Yulara, Northern Territory
On-site validation at Yulara, Northern Territory | © Civil Aviation Safety Authority

In January 2020, CASA finalised a significant three-year program to implement instrument approach procedures throughout Australia, to enhance aviation safety.

The International Civil Aviation Organization (ICAO) has identified the introduction of approach to landing procedures with vertical guidance as an internationally significant measure to reduce accidents involving controlled flight into terrain.


Barometric Vertical Navigation (Baro-VNAV) is one means of achieving approach procedures with vertical guidance. A Baro-VNAV approach provides lateral and vertical guidance to assist pilots during the final approach to an airport or aerodrome.

Australia’s Baro-VNAV implementation program commenced in 2016 as a result of ICAO Resolution A37-11, which called for implementation of approach procedures with vertical guidance for all instrument runway ends, either as the primary approach or as a back-up for precision approach procedures.

Flight validation of procedures by CASA is required by Civil Aviation Safety Regulations (CASR) Part 173 and ICAO Doc 9906; it is one of the final quality assurance steps in the instrument approach design process prior to the approach’s publication and use.

From the commencement of the Baro-VNAV validation program through to June 2020, CASA validated approximately 270 procedures at around 150 aerodromes. CASA will continue to validate new Baro-VNAV procedures as part of normal business, recovering the costs from
the procedure design organisation.

Other procedures

In addition to Baro-VNAV, CASA validated an additional 50 procedures, including the required navigation performance-authorisation approaches and the new approach and departure procedures for new runways at Brisbane Airport and Sunshine Coast Airport. The next flight validation program will involve validation of new procedures making use of Australia’s satellite-based augmentation system, which is planned to be commissioned in 2024.

Validation method

Although ICAO published guidelines for validation of approach procedures with vertical guidance, there was very little practical guidance on how to manage the validation efficiently, safely and cost-effectively.

In 2016, CASA developed a paper, CASA’s Methodology for Validation of Baro-VNAV Instrument Approaches, which was endorsed by ICAO’s Asia and Pacific Regions Flight Procedures Programme Steering Committee.

Procedures were validated in an aircraft simulator, using a B737 simulator and a custom-coded navigation database. The simulator validation component focuses on the navigation data and flyability of the procedures.

Different procedure coding methods were trialled to test different aircraft and flight management systems.

To implement the initial high-priority procedures in major regional areas, onsite validations were completed during standalone trips. The other onsite validations were included in CASA’s revalidation schedule. The onsite validation component focuses on ensuring a safe physical environment.

Added value

The simulator validation exercises add value for industry by providing excellent learning opportunities for CASA’s flight validation team, flying operations inspectors and procedure designers.

The flying operations inspectors were able to gain valuable experience flying new procedure types and to pass their experiences on to colleagues and industry. Procedure designers were able to increase their practical understanding by experiencing the procedures being flown in realistic simulations.