FLC MISINTERPRETS PDC AND FLIES WRONG RTE OVER ATLANTIC.

Date: 1993-07 · Aircraft: Widebody; Low Wing; 3 Turbojet Eng

Anomalies: deviation-track-heading-all-types|deviation-discrepancy-procedural-clearance

Synopsis

FLC MISINTERPRETS PDC AND FLIES WRONG RTE OVER ATLANTIC.

Narrative

ENRTE TO CDG WE HAD FILED FOR OCEANIC XING ON NAT TRACK 'VICTOR' AND WERE AWAITING CLRNC ON OUR ACARS; A RELATIVELY NEW PROC FOR OUR AIRLINE. NEAR GANDER; NEW FOUNDLAND; WHILE UNDER CTL OF ATC (RADAR CONTACT) OCEANIC CLRNC WAS INDEED RECEIVED ON ACARS AS FOLLOWS: 'ACR FLT CLRED TO LFPG VIA BANCS; RTE 45/50; 48/40; 50/30; 50/20; 50/15; KENAK; EXPECT FL310; MACH 0830.' PLEASE TAKE NOTE THAT 'BANCS' WAS A POINT ON OUR REQUESTED TRACK 'VICTOR' AND THE SUBSEQUENT POINTS WERE PART OF ANOTHER TRACK 'WHISKEY.' NOTE ALSO THAT THERE WAS NO CUE OR FLAG TO BRING ATTN THAT THIS WAS A MAJOR CHANGE (RERTE) TO OUR EXPECTED CLRNC. THE WORD 'VIA' USED WITH 'BANCS' FURTHER REINFORCED OUR MISTAKEN COMPREHENSION THAT TRACK VICTOR WAS THE INTENDED ROUTING. READBACK (VOICE) WAS GIVEN ON 134.9 STATING THAT CLRNC HAD BEEN RECEIVED AND READ AS FOLLOWS: 'CLRED VICTOR (!); BANCS; 45/50; 48/40; 50/30; 50/20; 50/15; KENAK....' GANDER OCEANIC DID NOT NOTICE THE ERROR IN THE READBACK 'VICTOR' AND RETURNED US TO DOMESTIC RADIO CTL. THE MISUNDERSTANDING WAS THAT WE WERE TO CONTINUE ON TRACK VICTOR; IN ITS ENTIRETY; AFTER THE FIRST CHKPOINT 'BANCS' AND WE WERE FURTHER MISTAKEN IN ASSUMING THAT THE COORDINATES OF THE ACARS SCREEN WERE THOSE OF TRACK 'VICTOR' AND THUS OUR INS PROGRAMMED ROUTING; WHEN IN FACT THEY WERE THOSE OF TRACK 'WHISKEY.' WE WERE THEN CLRED TO 45N/50W (UNDER RADAR CONTACT) AND THUS WE PROCEEDED DIRECTLY TOWARD OUR NEXT INS CHKPOINT AS LOADED (46N/50W). AGAIN AS NO MENTION WAS EVER MADE OF A ROUTING CHANGE OR A RERTE; WE ASSUMED THAT WE WOULD BE CONTINUING ON TRACK 'VICTOR.' ADMITTEDLY; THE 45N/50W WAS CHKED AGAINST THE ACARS SCREEN BUT NOT THE TRACK MESSAGE -- AT LEAST IMMEDIATELY AND ONLY IN OUR DELAYED PROCEDURAL CHK OF CLRNC AGAINST FLT PLAN ALONG WITH ALMOST SIMULTANEOUS QUERY BY ATC TO VERIFY OUR INTENTIONS; DID WE DISCOVER AND CORRECT THE ERROR (E.G.; PROCEEDING DIRECT BUT UNDER RADAR CONTACT TO THE WRONG POINT). DUE TO THE BENEFITS OF OPERATING 'RADAR CONTACT' BY ATC AND BY INCLUDING SEVERAL PEOPLE 'IN THE LOOP' (ATC; CREW; DISPATCH) ANY HAZARD TO OUR FLT WAS MINIMIZED AND CORRECTED BEFORE A LARGER PROB OCCURRED SUCH AS OFF- COURSE EXCURSION; TFC SEPARATION; ETC. HOWEVER; THIS PROB COULD HAVE BEEN AVOIDED ALTOGETHER BY EMPHASIZING AND INDEED INSISTING ON A PROC TO 'FLAG' OR 'HIGHLIGHT' OR BRING ATTN IN ANY OTHERWISE MANNER TO A CLRNC WHICH INVOLVES A MAJOR CHANGE SUCH AS A RERTE. TRACK NAMES; WHETHER ALPHA; NUMERIC; OR RANDOM; SHOULD BE MANDATORY IF APPLICABLE. PERHAPS SINCE FREQ CHANGES AS WELL AS DIFFERENT CTLRS ARE INVOLVED IN THE OCEANIC CLRNC PROCESS; VERIFICATION OF SOME SORT COULD BE USEFUL IN DETERMINING THE INTENTIONS OF ACFT/CREW.

Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.