HDG TRACK AND POS DEV AFTER ACFT EQUIP PROBLEM DEVELOPS IN NAV EQUIP.

Narrative

AT APPROX 30 MI S OF KRAFT ON AMBER 300 FROM SJU TO JFK; WHILE USING OMEGA NAV THE ACFT MADE A 20 DEG BANK AND L TURN ON A DIRECT COURSE TO DRAFT. WE RECEIVED A WARNING LIGHT; AN AMBIGUITY LIGHT AND DEAD RECKONING LIGHT. WE CHKED THE MALFUNCTION CODE AND CONSULTED THE BOOK; AND WARNINGS INDICATED AN INTERNAL SYS FAILURE. THE SYS WAS UNUSABLE; SO WE USED THE COMPUTER FLT PLAN FOR HDG INFO AND FLEW WITH THE ADF HEAD ON 176 DEGS; INFORMED NY RADIO ON HIGH FREQ THAT WE HAD LOST OUR OMEGA AND WE WERE DEAD RECKONING ON A-300 TO JFK AND REMINDED THEM OF THAT AT EVERY POS RPT. WE HAD BERMUDA ON ONE NAV AND STATIONS OFF THE E COAST ON THE OTHER RADIO. OUR TCASII ON THE 40 MI SCALE TO WATCH FOR OTHER ACFT. WE BEGAN TO RECEIVE ORF AND ATTEMPTED TO CALL NY CTR TO INFORM THEM WE WERE W OF COURSE. WHEN WE MADE CONTACT; THEY INFORMED US THAT THE MIL RADAR HAD US IN CONTACT AND THEY KNEW WHERE WE WERE. THEY GAVE US A HDG FOR JFK AND WE LANDED. I THINK ONE OF THE NEW HAND-HELD GNS SYS WOULD BE A HANDY MACHINE TO KEEP IN YOUR BAG JUST IN CASE IT HAPPENS AGAIN.