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Session 5: GBAS Inspection, Operational Experience

Challenges with GBAS VDB Flight Inspection
Mike Spanner, NATS, United Kingdom
Location: Regency Ballroom
Date/Time: Tuesday, Apr. 17, 4:00 p.m.

Flight Inspection of GBAS presents many challenges compared to traditional navigation facilities. The VDB SARPS include not only minimum field strengths, but also include maximum figures in order to ensure the maximum data transmission loss rates are not exceeded. This, coupled to the use of multiple VDB transmitter locations supporting the same approach, leads to a complex set of flight inspection requirements and new measurement uncertainty evaluations to be performed. Along with this, it is noted that ICAO are currently examining the potential effect of ILS and VOR overflights which may affect the ability of the GBAS VDB receiver to perform correctly. This may lead to the necessity of performing measurements to evaluate potential adjacent-channel interference issues.
This paper examines practical flight inspection results and uses the measurements to highlight where improvements in measurements techniques and resultant uncertainty specification are required. Evaluation of the latest recommendations being discussed within ICAO that may affect flight inspection measurements are also presented.



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