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Flight crew of a B737 at cruise has a problem with an 'left' VOR not giving them accurate indications on the cleared route. ATC advises they are 6 DME off course.
| Attributes | |
| ACN | 429611 |
| Time | |
| Date | 199903 |
| Day | Tue |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | navaid : esl.vortac |
| State Reference | WV |
| Altitude | msl single value : 14000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdc.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other vortac |
| Flight Phase | cruise : level |
| Route In Use | enroute : direct enroute airway : v377.airway |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 210 flight time total : 23000 flight time type : 5000 |
| ASRS Report | 429611 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : flight engineer pilot : atp |
| Experience | flight time last 90 days : 200 flight time total : 14000 flight time type : 8000 |
| ASRS Report | 429887 |
| Events | |
| Anomaly | other anomaly other other spatial deviation |
| Independent Detector | atc equipment other atc equipment : radar other controllera other flight crewa |
| Resolutory Action | controller : issued advisory flight crew : became reoriented |
| Supplementary | |
| Problem Areas | Airspace Structure |
| Primary Problem | Airspace Structure |
Narrative:
We were cleared direct esl VOR. We had to ask center for a heading because the VOR is so weak. After esl VOR, we were cleared V377 to hgr VOR and on to har VOR. Around tomac intersection we lost DME off esl VOR and hgr VOR needle was swinging back and forth. Center told us we were 6 DME northwest of hgr VOR. We told him the problems we were having, identing tomac intersection to make the turn on the airway. I don't think center should issue a direct to a VOR that is an 'left' class VOR, when you are too far away to receive the signal. Both our VOR needles were unreliable on hgr VOR so I don't believe it was our equipment. If they (ATC) want us to navigation, we need a reliable station to do it properly. There was no incident involved. Supplemental information from acn 429887: factors affecting our navigation include: 1) distances and terrain influences of the use of low power vors, including altitudes, for flight planning purposes. 2) strong inclination of interference of an onboard electronic device being used by a passenger (phone, laptop computer, video games). I have seen this same type of interference before with electronic devices.
Original NASA ASRS Text
Title: FLC OF A B737 AT CRUISE HAS A PROB WITH AN 'L' VOR NOT GIVING THEM ACCURATE INDICATIONS ON THE CLRED RTE. ATC ADVISES THEY ARE 6 DME OFF COURSE.
Narrative: WE WERE CLRED DIRECT ESL VOR. WE HAD TO ASK CTR FOR A HDG BECAUSE THE VOR IS SO WEAK. AFTER ESL VOR, WE WERE CLRED V377 TO HGR VOR AND ON TO HAR VOR. AROUND TOMAC INTXN WE LOST DME OFF ESL VOR AND HGR VOR NEEDLE WAS SWINGING BACK AND FORTH. CTR TOLD US WE WERE 6 DME NW OF HGR VOR. WE TOLD HIM THE PROBS WE WERE HAVING, IDENTING TOMAC INTXN TO MAKE THE TURN ON THE AIRWAY. I DON'T THINK CTR SHOULD ISSUE A DIRECT TO A VOR THAT IS AN 'L' CLASS VOR, WHEN YOU ARE TOO FAR AWAY TO RECEIVE THE SIGNAL. BOTH OUR VOR NEEDLES WERE UNRELIABLE ON HGR VOR SO I DON'T BELIEVE IT WAS OUR EQUIP. IF THEY (ATC) WANT US TO NAV, WE NEED A RELIABLE STATION TO DO IT PROPERLY. THERE WAS NO INCIDENT INVOLVED. SUPPLEMENTAL INFO FROM ACN 429887: FACTORS AFFECTING OUR NAV INCLUDE: 1) DISTANCES AND TERRAIN INFLUENCES OF THE USE OF LOW PWR VORS, INCLUDING ALTS, FOR FLT PLANNING PURPOSES. 2) STRONG INCLINATION OF INTERFERENCE OF AN ONBOARD ELECTRONIC DEVICE BEING USED BY A PAX (PHONE, LAPTOP COMPUTER, VIDEO GAMES). I HAVE SEEN THIS SAME TYPE OF INTERFERENCE BEFORE WITH ELECTRONIC DEVICES.
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.