NORTH ATLANTIC ADS WAYPOINT REPORTING TRIALS.

John CoulsonNATS 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

AFT NCENT RAL ADS (CADS)

SYST EM

ARINCNET W O RK

ScO ACC,(PREST W ICK)

G ANDERO ACC

(ARINC, Annapolis)

A D S C ontrac t R equestsA D S reports

VHF

SAT CO M

PO S reports(AFTN format)

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)

0

200

400

600

800

1000

1200

1400

FANS HF

FANS TRANSMISSION DELAYS

0

10000

20000

30000

40000

50000

60000

70000

< -1 -1 0 1 2 3 4 5-9 10+

Transmission delay (minutes)

sample size 89171 mean 0.154 (mins)mode 0std. dev. 1.3195 %ile -195 %ile 2max 15min -60

HF VOICE TRANSMISSION DELAYS

0

50000

100000

150000

200000

250000

300000

< -1 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20+

Transmission delay (minutes)

sample size 1002353 mean 3.667 (mins)mode 2std. dev. 7.5945 %ile 195 %ile 9max 1209min -1372

DATA ANALYSIS

Comparison of FANS & HF time delay performance:

- Mean HF delay 3.7 mins- Mean FANS/1 delay 0.15 mins- Mean difference 3.1 mins (between equivalent

FANS & HF reports)- 89.6% 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

0

5000

10000

15000

20000

25000

<-5 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20+

Arrival time difference (minutes)

sample size 75722 mean 3.091 (mins)mode 2std. dev. 3.5075 %ile 095 %ile 8max 104min -119

FANS slower than HF HF slower than FANS

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

AFTN Delay (mins)

0

10000

20000

30000

40000

50000

60000

70000

80000

-2 -1 0 1 2 3 4 5-9 10+

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

0

10

20

30

40

50

60

70

80

90

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

-60

0

60

120

180

240

300

360

420

480

540

600

FANS SUMMARY STATISTICS (1)

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

0.00%

2.00%

4.00%

6.00%

8.00%

10.00%

12.00%

14.00%

16.00%

18.00%

24 6 3 4 A 7a 7b 9 21

Issue/Observation Register No.

24 Duplicate reports 6 Extra POS report 3 E'bnd Domestic Bdy report 4 W'bnd Pre bdy report A E'bnd East of domestic bdy report * 7a Blank Time field 7b Blank Time field (ATC reports only) 9 Next POS same as POS 21 Next POS non-ATC (ATC reports)

* Not applicable before 19/11/99

FANS SUMMARY STATISTICS (2)

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

0.00%

2.00%

4.00%

6.00%

8.00%

10.00%

12.00%

14.00%

10a 10b 14 10c 10d 11

Issue/Observation Register No.

10a Missing W'bnd 30W report 10b Missing W'bnd 20W report 14 Missing W'bnd domestic bdy report 10c Missing E'bnd 30W report 10d Missing E'bnd 20W report 11 Different Callsign from HF report

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).