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A military medium large transport aircraft had problems with its TACAN mileage locking up while passing over a VORTAC. ATC noticed this and issued a vector clearance. Retuning the TACAN caused it to work properly.
| Attributes | |
| ACN | 208173 |
| Time | |
| Date | 199204 |
| Day | Mon |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : bld airport : lsv |
| State Reference | NV |
| Altitude | msl bound lower : 14000 msl bound upper : 14000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Operator | other |
| Make Model Name | Medium Transport, Low Wing, 2 Turbojet Eng |
| Navigation In Use | Other |
| Flight Phase | cruise other descent other |
| Route In Use | arrival other arrival star : star enroute : on vectors enroute airway : las |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : military |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : instrument pilot : flight engineer pilot : commercial pilot : atp |
| Experience | flight time last 90 days : 200 flight time total : 6000 flight time type : 450 |
| ASRS Report | 208173 |
| Person 2 | |
| Affiliation | government : military |
| Function | flight crew : first officer |
| Qualification | pilot : military |
| Events | |
| Anomaly | aircraft equipment problem : less severe non adherence : published procedure non adherence : clearance other spatial deviation |
| Independent Detector | other controllera other flight crewa |
| Resolutory Action | controller : issued new clearance flight crew : became reoriented flight crew : overcame equipment problem |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Our clearance was the fuzzy 3 arrival to las, landing at nellis AFB (landing runway 21). The clearance was to proceed direct nellis TACAN once passing boulder VORTAC. ATC gave us a turn to 070 degrees, and asked if we were proceeding to lsv, as we had been cleared. Our DME still showed about over boulder. When asked, ATC said they showed us 30 DME southeast of boulder. When we switched the vors to another frequency and back to boulder, they then indicated our position as 25-30 DME from boulder. We reported to ATC that apparently the DME had locked up over the station, so we had missed our turn direct lsv. ATC did not again refer to the event. Main lesson learned: keep in mind where you are, not just that the DME bearing pointer shows the station is behind you! We should obviously have been aware that it was taking too long (!!) to get to/away from boulder.
Original NASA ASRS Text
Title: A MIL MLG ACFT HAD PROBLEMS WITH ITS TACAN MILEAGE LOCKING UP WHILE PASSING OVER A VORTAC. ATC NOTICED THIS AND ISSUED A VECTOR CLRNC. RETUNING THE TACAN CAUSED IT TO WORK PROPERLY.
Narrative: OUR CLRNC WAS THE FUZZY 3 ARR TO LAS, LNDG AT NELLIS AFB (LNDG RWY 21). THE CLRNC WAS TO PROCEED DIRECT NELLIS TACAN ONCE PASSING BOULDER VORTAC. ATC GAVE US A TURN TO 070 DEGS, AND ASKED IF WE WERE PROCEEDING TO LSV, AS WE HAD BEEN CLRED. OUR DME STILL SHOWED ABOUT OVER BOULDER. WHEN ASKED, ATC SAID THEY SHOWED US 30 DME SE OF BOULDER. WHEN WE SWITCHED THE VORS TO ANOTHER FREQ AND BACK TO BOULDER, THEY THEN INDICATED OUR POS AS 25-30 DME FROM BOULDER. WE RPTED TO ATC THAT APPARENTLY THE DME HAD LOCKED UP OVER THE STATION, SO WE HAD MISSED OUR TURN DIRECT LSV. ATC DID NOT AGAIN REFER TO THE EVENT. MAIN LESSON LEARNED: KEEP IN MIND WHERE YOU ARE, NOT JUST THAT THE DME BEARING POINTER SHOWS THE STATION IS BEHIND YOU! WE SHOULD OBVIOUSLY HAVE BEEN AWARE THAT IT WAS TAKING TOO LONG (!!) TO GET TO/AWAY FROM BOULDER.
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.