Narrative:

On 5/90 company operated an heavy transport on a mac charter, kwri, bgsf, bgtl, kwri. I am a company check pilot, long range navigation instrument/check airman. I was on the heavy transport aircraft to qualify the operating crew into bgsk. On the northbound ldg, kwri-bgsf, when the captain made his 65000 ft.060000W progress report, cygn octa informed him of this situation and did an ADF/radar pilot and determined that at this time we were in fact 3-5 mi north of track. On arrival at bgsf the omega error was 2.6 mi left and .4 mi long track error on #1 omega. The #2 omega was 38 mi right and 22 mi short on track. We proceeded bgsf-bgtl on organized arwys. On arrival at bgtl the errors were noted (#1 O.1L.--meeting=-1.5) (#2 was 12.3 right--2.9+ on meeting.) with this information in mind I decided that I would operate the aircraft bgtl-kwri. Our clearance was kwri-SID-dir 70N 060 west dir 65 north 060 west 60N. 60W. Dir ho (hopedale coast in point) dir. Alman dir. Pqi J564 J55 ene. J581 put. J225/J42 rbv. Dir kwri, expect FL310, squawk XXXX. As the aircraft was approaching 70N 060 west I noticed that the aircraft was in a left turn (aircraft autoplt was in the heading select mode, the omega was not steering the aircraft). The heading system were slowly precessing to the right. The standby compass was turning to the left. I disconnected the autoplt and head a visibility heading. As both omegas were in the dr mode and to my consternation the #1 omega was reading 135.6 right. The #2 omega was 94.0L. I had the hb (holsteingsborg) NDB was tuned into both ADF's. I contacted thule radio and declared 'my long range navigation system appear to be unreliable, and I would like a clearance from present position to hb dir st (sukkertoppen) dir ki (kook island) dir 60 north 060 west dir ho (hopedale), then as filed.' I was so cleared by iceland control. I forwarded the appropriate estimates. Overhead ho the #1 omega were .3 right xtrack and +5.7 ltrack. It must be noted that #2 omega was us. The signal strength for #1 was very degradated. The signal strength was station 1 (norway) 16, station 4, (nd) was 88 and #6 (argentina) was 42. These with LF stations 1, 3, 5 and 7 were also very weak. When we reached the us both omega antennas were changed. They were both 'full of water,' thus not reliable. The company is presently checking into #3 generator, which would clear the compass excursion problem. My recommendations are as follows: 1) rechk the antenna locations, does water run into them if on bottom. 2) put these antennas on a cycle check. 3) the use of better quality, state of the art sealants around the antennas.

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Original NASA ASRS Text

Title: CHARTER HVT TRACK HEADING DEVIATION ON EXTENDED OVERWATER OPERATION.

Narrative: ON 5/90 COMPANY OPERATED AN HVT ON A MAC CHARTER, KWRI, BGSF, BGTL, KWRI. I AM A COMPANY CHK PLT, LONG RANGE NAV INSTR/CHK AIRMAN. I WAS ON THE HVT ACFT TO QUALIFY THE OPERATING CREW INTO BGSK. ON THE NBOUND LDG, KWRI-BGSF, WHEN THE CAPT MADE HIS 65000 FT.060000W PROGRESS RPT, CYGN OCTA INFORMED HIM OF THIS SIT AND DID AN ADF/RADAR PLT AND DETERMINED THAT AT THIS TIME WE WERE IN FACT 3-5 MI N OF TRACK. ON ARR AT BGSF THE OMEGA ERROR WAS 2.6 MI L AND .4 MI LONG TRACK ERROR ON #1 OMEGA. THE #2 OMEGA WAS 38 MI R AND 22 MI SHORT ON TRACK. WE PROCEEDED BGSF-BGTL ON ORGANIZED ARWYS. ON ARR AT BGTL THE ERRORS WERE NOTED (#1 O.1L.--MEETING=-1.5) (#2 WAS 12.3 RIGHT--2.9+ ON MEETING.) WITH THIS INFO IN MIND I DECIDED THAT I WOULD OPERATE THE ACFT BGTL-KWRI. OUR CLRNC WAS KWRI-SID-DIR 70N 060 W DIR 65 N 060 W 60N. 60W. DIR HO (HOPEDALE COAST IN POINT) DIR. ALMAN DIR. PQI J564 J55 ENE. J581 PUT. J225/J42 RBV. DIR KWRI, EXPECT FL310, SQUAWK XXXX. AS THE ACFT WAS APCHING 70N 060 W I NOTICED THAT THE ACFT WAS IN A L TURN (ACFT AUTOPLT WAS IN THE HDG SELECT MODE, THE OMEGA WAS NOT STEERING THE ACFT). THE HDG SYS WERE SLOWLY PRECESSING TO THE R. THE STANDBY COMPASS WAS TURNING TO THE L. I DISCONNECTED THE AUTOPLT AND HEAD A VIS HDG. AS BOTH OMEGAS WERE IN THE DR MODE AND TO MY CONSTERNATION THE #1 OMEGA WAS READING 135.6 R. THE #2 OMEGA WAS 94.0L. I HAD THE HB (HOLSTEINGSBORG) NDB WAS TUNED INTO BOTH ADF'S. I CONTACTED THULE RADIO AND DECLARED 'MY LONG RANGE NAV SYS APPEAR TO BE UNRELIABLE, AND I WOULD LIKE A CLRNC FROM PRESENT POS TO HB DIR ST (SUKKERTOPPEN) DIR KI (KOOK ISLAND) DIR 60 N 060 W DIR HO (HOPEDALE), THEN AS FILED.' I WAS SO CLRED BY ICELAND CTL. I FORWARDED THE APPROPRIATE ESTIMATES. OVERHEAD HO THE #1 OMEGA WERE .3 R XTRACK AND +5.7 LTRACK. IT MUST BE NOTED THAT #2 OMEGA WAS US. THE SIGNAL STRENGTH FOR #1 WAS VERY DEGRADATED. THE SIGNAL STRENGTH WAS STATION 1 (NORWAY) 16, STATION 4, (ND) WAS 88 AND #6 (ARGENTINA) WAS 42. THESE WITH LF STATIONS 1, 3, 5 AND 7 WERE ALSO VERY WEAK. WHEN WE REACHED THE U.S. BOTH OMEGA ANTENNAS WERE CHANGED. THEY WERE BOTH 'FULL OF WATER,' THUS NOT RELIABLE. THE COMPANY IS PRESENTLY CHKING INTO #3 GENERATOR, WHICH WOULD CLR THE COMPASS EXCURSION PROB. MY RECOMMENDATIONS ARE AS FOLLOWS: 1) RECHK THE ANTENNA LOCATIONS, DOES WATER RUN INTO THEM IF ON BOTTOM. 2) PUT THESE ANTENNAS ON A CYCLE CHK. 3) THE USE OF BETTER QUALITY, STATE OF THE ART SEALANTS AROUND THE ANTENNAS.

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.