ACR X 5 MI S OF AIRWAY CDI SHOWED CTRLINE OF AIRWAY. DPK 320 RADIAL UNRELIABLE AT LOWER ALT.

Narrative

THIS IS THE SECOND RPT I HAVE FILED CONCERNING NAV PROBS AROUND GAYEL INTXN. THE CAPT OPTED FOR A LOWER ALT TO AVOID SOME HEADWINDS. (NORMALLY WE OPERATE AT 14000-17000 IN THIS AREA). SOME 5-10 NM SE OF GAYEL (ACCORDING TO OUR VORS). THE CTLR ASKED IF WE WERE STILL ESTABLISHED ON THE DPK 320 DEG RADIAL. I REPLIED; 'AFFIRMATIVE;' AS 1 CDI SHOWED CTRING OF THE AIRWAY. (THE OTHER CDI WAS TUNED TO THE APCHING CPB 129 DEG RADIAL -- THE BEND IN THE AIRWAY AT GAYEL). I THEN QUESTIONED THE CTLR AS TO WHETHER HE CONCURRED WITH OUR POS. HE REPLIED THAT HE SHOWED US 4-5 MI S OF THE AIRWAY; APPEARING TO PARALLEL THE COURSE. NO VECTOR WAS GIVEN TO CORRECT; AND WE STILL SHOWED ON COURSE; PASSING GAYEL; NOW HDG TO CF8. A SHORT TIME LATER; WE WERE INSTRUCTED TO CLB TO 13000 FT AS 12000 FT WAS UNUSUAL (UNAVAILABLE) DUE TO TFC AT OUR 11-12 O'CLOCK AT 6 NM (TFC WAS IN SIGHT). WE COMPLIED AND AGAIN STATED THAT WE CONTINUED TO SHOW ON COURSE. THE CTLR MADE A PASSING STATEMENT THAT ; 'PERHAPS THAT RADAR IS UNUSABLE.' AS I HAVE STATED IN MY EARLIER RPT; THIS TYPE OF THING HAPPENS ABOUT 30-40 PERCENT OF THE TIME ON THIS RTE (IN MY PERSONAL EXPERIENCE).