FANS ADS-WPR

By Kjell Sandberg, SAS

"ADS-WPR" means Automatic Dependant Surveillance – Waypoint Position Report. In other words, an automatically generated waypoint position report transmitted via datalink.

When flying in oceanic airspace where there is no radar coverage, the pilot must report to ATC the exact time the waypoints along the flight path are passed. The reports are traditionally made via voice HF-radio when there is no VHF-coverage. The HF voice reports are transcribed by a radio operator and sent to the ATC center as a telex.

HF voice frequences on the North Atlantic are often congested making it difficult for pilots to send their position reports at the right time. Poor HF transmission conditions mean that the reports may have to be re-transmitted or relayed by other aircraft. This consumes time and effort by pilots, radio operators and controllers, and increase the risk for errors.

SAS Airbus A340 and A330 aircraft are equipped with the Airbus "FANS-A" package. As from 2002 the aircraft send Waypoint Position Reports automatically and directly to ATC on North Atlantic routes via datalink (Acars VHF or SATCOM). ATC centers receive an indication that the aircraft is ADS-capable and activate waypoint position reporting from the aircraft.

The risk for mishearing or misunderstanding is almost eliminated and thus safety is enhanced. The WPRs are delivered to ATC in near-real time and with higher reliability than on via voice.

Currently Reykjavik, Gander and Shanwick FIRs in NAT have operational trials ongoing. Bodö FIR will start operational trial during 2003.

"FANS" stands for Future Air Navigation System. It is a set of applications for Air Traffic Control based on modern technologies such as datalink communication and satellite navigation. In this context FANS is a set of ATS datalink applications that allow the aircraft to communicate direct with ATC centers on ground. The two main applications in FANS are ADS-WPR and CPDLC.

FANS ADS report displayed on a SAS' Airbus 330 DCDU.
Picture by K. Sandberg, SAS

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