Narrative:

On flight from ft lauderdale international airport (fll) to long island mac arthur (isp) we requested a direct route to calverton VORTAC (CCC, 117.20 MHZ) from ZDC. The controller then asked our position and to verify our assigned routing. We responded with, 'J174 then J121 CCC etc, to isp.' he remarked on our present position and requested a turn to rejoin J121. Having flown FAA flight check previously for 3 yrs, (we) I felt a major contributor in this discrepancy is the unreliability of snow hill VORTAC (swl, 112.40 MHZ). We noted our position as slightly east of J121 (no more than 4 mi), however, we complied with the controller's instructions. The periodicity for VOR flight checks has over the yrs increased from 365 days to 1086 days. This allows a facility the opportunity to become less than adequate for navigation over a greater period of time. User complaints on this facility are/have been unaddressed according to our ATC query. In view of this perhaps a joint effort between pilots (of manual/traditional navigation aircraft) and ATC controllers, for vigilance as to centerline/on-course verification would thwart any possible off-course, navigation error problems from occurring. Supplemental information from acn 563101: I think the majority of contribution lies with the ever present unreliability of swl as a NAVAID. Winds had shifted significantly to the west from the previous evening's travels as well, and were unusually strong. Crew and controller vigilance are also areas which leave room for improvement, as always, especially were navigation off of swl with traditional non GPS, non FMS aircraft are concerned. Callback conversation with ARTCC specialist on acn 563100: a conversation with an ARTCC specialist revealed that the 'snow hill' VORTAC does indeed express navigation wavering 3-5 mi east of the projected airway. Maintenance on the facility, planned during nov of 2002, has been rescheduled for jan of 2003.

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Original NASA ASRS Text

Title: A B737 CREW, IN CRUISE AT FL330, WERE QUERIED BY ATC AS TO THEIR POS RELATIVE TO SWL VORTAC, THEN ISSUED A HEADING TO REJOIN THE FILED AIRWAY.

Narrative: ON FLT FROM FT LAUDERDALE INTL ARPT (FLL) TO LONG ISLAND MAC ARTHUR (ISP) WE REQUESTED A DIRECT RTE TO CALVERTON VORTAC (CCC, 117.20 MHZ) FROM ZDC. THE CTLR THEN ASKED OUR POS AND TO VERIFY OUR ASSIGNED ROUTING. WE RESPONDED WITH, 'J174 THEN J121 CCC ETC, TO ISP.' HE REMARKED ON OUR PRESENT POS AND REQUESTED A TURN TO REJOIN J121. HAVING FLOWN FAA FLT CHK PREVIOUSLY FOR 3 YRS, (WE) I FELT A MAJOR CONTRIBUTOR IN THIS DISCREPANCY IS THE UNRELIABILITY OF SNOW HILL VORTAC (SWL, 112.40 MHZ). WE NOTED OUR POS AS SLIGHTLY E OF J121 (NO MORE THAN 4 MI), HOWEVER, WE COMPLIED WITH THE CTLR'S INSTRUCTIONS. THE PERIODICITY FOR VOR FLT CHKS HAS OVER THE YRS INCREASED FROM 365 DAYS TO 1086 DAYS. THIS ALLOWS A FACILITY THE OPPORTUNITY TO BECOME LESS THAN ADEQUATE FOR NAV OVER A GREATER PERIOD OF TIME. USER COMPLAINTS ON THIS FACILITY ARE/HAVE BEEN UNADDRESSED ACCORDING TO OUR ATC QUERY. IN VIEW OF THIS PERHAPS A JOINT EFFORT BTWN PLTS (OF MANUAL/TRADITIONAL NAV ACFT) AND ATC CTLRS, FOR VIGILANCE AS TO CTRLINE/ON-COURSE VERIFICATION WOULD THWART ANY POSSIBLE OFF-COURSE, NAV ERROR PROBS FROM OCCURRING. SUPPLEMENTAL INFO FROM ACN 563101: I THINK THE MAJORITY OF CONTRIBUTION LIES WITH THE EVER PRESENT UNRELIABILITY OF SWL AS A NAVAID. WINDS HAD SHIFTED SIGNIFICANTLY TO THE W FROM THE PREVIOUS EVENING'S TRAVELS AS WELL, AND WERE UNUSUALLY STRONG. CREW AND CTLR VIGILANCE ARE ALSO AREAS WHICH LEAVE ROOM FOR IMPROVEMENT, AS ALWAYS, ESPECIALLY WERE NAV OFF OF SWL WITH TRADITIONAL NON GPS, NON FMS ACFT ARE CONCERNED. CALLBACK CONVERSATION WITH ARTCC SPECIALIST ON ACN 563100: A CONVERSATION WITH AN ARTCC SPECIALIST REVEALED THAT THE 'SNOW HILL' VORTAC DOES INDEED EXPRESS NAV WAVERING 3-5 MI E OF THE PROJECTED AIRWAY. MAINT ON THE FACILITY, PLANNED DURING NOV OF 2002, HAS BEEN RESCHEDULED FOR JAN OF 2003.

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.