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Giii is determined by radar to be 35 mi south of course even though the aircraft navigation gear showed the aircraft to be on course.
| Attributes | |
| ACN | 351729 |
| Time | |
| Date | 199610 |
| Day | Wed |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : yqx |
| State Reference | NF |
| Altitude | msl bound lower : 43000 msl bound upper : 43000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : czqx |
| Operator | general aviation : corporate |
| Make Model Name | Gulfstream III |
| Operating Under FAR Part | Part 91 |
| Navigation In Use | Other Other |
| Flight Phase | cruise other |
| Route In Use | enroute : other oceanic enroute : atlantic |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | Other |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 90 flight time total : 3250 flight time type : 680 |
| ASRS Report | 351729 |
| Person 2 | |
| Affiliation | Other |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 90 flight time total : 12500 flight time type : 1500 |
| ASRS Report | 351595 |
| Events | |
| Anomaly | non adherence : clearance non adherence : far other spatial deviation |
| Independent Detector | other controllera |
| Resolutory Action | none taken : detected after the fact |
| Consequence | faa : reviewed incident with flight crew Other |
| Supplementary | |
| Primary Problem | Ambiguous |
| Air Traffic Incident | other |
Narrative:
On a trans-atlantic flight from eggw to bgr, a giii was cleared via the flight plan along the nats. Nxxx has 3 long range navigation (lrn) system certified to use the nats: an FMS and 2 INS's. At our final latitude/longitude coordinate (N52 W050), we contacted first gander radio and then gander radar on VHF radio. After we gave our position report: 'nxxx 52050 at XA20, FL430, estimate dotty at XA50, topps next.' we were assigned a transponder code and cleared direct to bangor. We selected 'dto' on the FMS and proceeded direct to bgr. Shortly thereafter, gander radar said we were 40 mi south of 52050 and there appeared to be a gross navigation error. We immediately ran checks. I asked gander radar for a position fix and all 3 lrn's agreed with the coordinates they gave us (N5050, W5205). We checked the FMS data page 3/4 for the accuracy of the FMS sensor inputs. A subsequent check of the FMS data page 2/4 showed an FMS quality factor of 'Q01.' upon landing a bgr we checked the ramp coordinates with the 3 lrn's. A subsequent phone call to the gander radar shift manager confirmed their radar track showed nxxx was 35 NM south of 52050 at N51 12.59 W50 34.52 and they were filing a gross navigation error report to the nats coordinating committee and the canadian mot.
Original NASA ASRS Text
Title: GIII IS DETERMINED BY RADAR TO BE 35 MI S OF COURSE EVEN THOUGH THE ACFT NAV GEAR SHOWED THE ACFT TO BE ON COURSE.
Narrative: ON A TRANS-ATLANTIC FLT FROM EGGW TO BGR, A GIII WAS CLRED VIA THE FLT PLAN ALONG THE NATS. NXXX HAS 3 LONG RANGE NAV (LRN) SYS CERTIFIED TO USE THE NATS: AN FMS AND 2 INS'S. AT OUR FINAL LATITUDE/LONGITUDE COORDINATE (N52 W050), WE CONTACTED FIRST GANDER RADIO AND THEN GANDER RADAR ON VHF RADIO. AFTER WE GAVE OUR POS RPT: 'NXXX 52050 AT XA20, FL430, ESTIMATE DOTTY AT XA50, TOPPS NEXT.' WE WERE ASSIGNED A XPONDER CODE AND CLRED DIRECT TO BANGOR. WE SELECTED 'DTO' ON THE FMS AND PROCEEDED DIRECT TO BGR. SHORTLY THEREAFTER, GANDER RADAR SAID WE WERE 40 MI S OF 52050 AND THERE APPEARED TO BE A GROSS NAV ERROR. WE IMMEDIATELY RAN CHKS. I ASKED GANDER RADAR FOR A POS FIX AND ALL 3 LRN'S AGREED WITH THE COORDINATES THEY GAVE US (N5050, W5205). WE CHKED THE FMS DATA PAGE 3/4 FOR THE ACCURACY OF THE FMS SENSOR INPUTS. A SUBSEQUENT CHK OF THE FMS DATA PAGE 2/4 SHOWED AN FMS QUALITY FACTOR OF 'Q01.' UPON LNDG A BGR WE CHKED THE RAMP COORDINATES WITH THE 3 LRN'S. A SUBSEQUENT PHONE CALL TO THE GANDER RADAR SHIFT MGR CONFIRMED THEIR RADAR TRACK SHOWED NXXX WAS 35 NM S OF 52050 AT N51 12.59 W50 34.52 AND THEY WERE FILING A GROSS NAV ERROR RPT TO THE NATS COORDINATING COMMITTEE AND THE CANADIAN MOT.
Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.