NORTH ATLANTIC ADS WAYPOINT REPORTING TRIALS. John Coulson NATS Infrastructure Services

NAV CANADA & NATS commenced trial 15 July 1999 in Gander & Shanwick OCAs using centralised ADS (CADS) system located at ARINC, Annapolis. When aircraft logs on, CADS system initiates: - Waypoint event ADS contract - Periodic ADS contract for Met data (selected a/c) CADS system converts ADS reports from aircraft, converts these to AFTN POS reports and sends to ScOACC, Prestwick via AFTN. POS reports received at ScOACC analysed and compared with HF voice originated reports. INTRODUCTION

SYSTEM DIAGRAM

AIM OF TRIALS To accommodate FANS-1/A equipped aircraft by enabling them to replace existing position reporting using HF voice by datalinked reports. No separation reductions planned as a result of trials but potential benefits include: - Reduction of HF voice congestion. - Reduction of flight crew workload. - Improve safety by early identification of potential Gross Navigation Errors (GNE).

Number of flights/day (Shanwick)

FANS TRANSMISSION DELAYS

HF VOICE TRANSMISSION DELAYS

DATA ANALYSIS Comparison of FANS & HF time delay performance: - Mean HF delay3.7 mins - Mean FANS/1 delay 0.15 mins - Mean difference3.1 mins (between equivalent FANS & HF reports) % of FANS reports faster than HF Investigation of AFTN delays. - 95% of messages within 1 min BUT occasional delays & message losses seen. Comparison of POS report content of FANS & HF messages.

DIFFERENCE IN ARRIVAL TIMES BETWEEN FANS & HF VOICE REPORTS

AFTN DELAYS FOR FANS REPORTS (CACC time - CADS time) AFTN Delay (mins )

NUMBER OF FANS REPORTS/DAY WITH AFTN DELAY OF >10 MINS (15/7/99 to 21/8/00)

MAXIMUM AFTN DELAY BY DAY FOR ALL FANS REPORTS (15/7/99 to 21/8/00)

FANS SUMMARY STATISTICS (1) Issue/Observation Register No. (for weeks beginning 6/10/99 to 16/8/00)

FANS SUMMARY STATISTICS (2) Issue/Observation Register No. (for weeks beginning 6/10/99 to 16/8/00)

NON-MATCHING CALLSIGNS Following CADS software upgrade on 30/6/00, callsigns as entered on flight deck are included in ADS reports. ATC requires callsign exactly as in filed flight plan (3 letter ICAO airline ID + flight number eg BAW 123) Significant variations have been seen: - No airline ID (eg 86) - 2 letter IATA airline ID (eg UA928) - Leading zero in FANS flight number (eg AAL047) - Two leading zeroes in FANS flight number (eg SVA 0055) - Leading zero in HF voice flight number (eg SIA024)

NON-MATCHING CALLSIGNS Reflects previous NATS trials experience (also mentioned in Eurocontrol Petal- II report). Not been critical to date since callsign has not been used outside aircraft avionics but now need to standardise. Correct callsign entry will be vital when CPDLC introduced (if incorrect, aircraft will not be able to log on).

SUMMARY & CONCLUSIONS (1) FANS-1/A time delay performance superior to HF voice. HF exhibits higher error rate than FANS-1/A (probably due to transcription errors). Some problems remain: - CADS filtering changes required to remove unwanted reports. - Occasional AFTN delays (Ground network changes reqd). - Differences between FANS-1/A & HF reports (more minor). - Non-ATC waypoints. - ADS Met report errors from B777 aircraft. - Non-matching callsigns. NAV CANADA analyses have shown similar results.

SUMMARY & CONCLUSIONS (2) NATSPG FANS Implementation Group (FIG) agreed one month of “problem free” traffic required before any transition to operational status. Current estimates indicate system operational later in 2000.

TRIALS DEVELOPMENTS (1) Use of FANS-1/A Controller/Pilot Data Link Comms (CPDLC). Phased implementation proposed to permit: - Flight crew requests for speed & altitude changes (response via HF voice). - Advising domestic VHF frequencies (eastbound flights). - Flight crew requests for speed & altitude changes (response via datalink - CPDLC). (NB: NATSPG has stated that SARPs compliant systems using the ATN remain the “end goal” for the NAT region. It is intended to ensure that the transition to SARPs compliant CPDLC will be seamless to users)

TRIALS DEVELOPMENTS (2) Proposed trial of FMC based position reporting (non-ADS). Proposed trial of HFDL.

THE FUTURE NATS sees the introduction of Datalink on the North Atlantic as a key move to increase efficiency in this region. ADS WPR continues to build NATS expertise in use of ADS (complements the previous ADS Europe trials). ADS & Controller/Pilot Data Link Comms ( CPDLC) are the enablers for future benefits on the NAT (eg increased capacity).