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Flight crew of mdt atx aircraft deviated from assigned track due to entry error in the aircraft flight navigation computer.
| Attributes | |
| ACN | 211249 |
| Time | |
| Date | 199205 |
| Day | Sun |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : sln |
| State Reference | KS |
| Altitude | msl bound lower : 35000 msl bound upper : 35000 |
| Environment | |
| Flight Conditions | IMC |
| Aircraft 1 | |
| Controlling Facilities | artcc : zkc |
| Operator | common carrier : air taxi |
| Make Model Name | Medium Transport |
| Navigation In Use | Other |
| Flight Phase | climbout : intermediate altitude cruise other descent other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air taxi |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : cfi pilot : atp |
| Experience | flight time last 90 days : 50 flight time total : 4300 flight time type : 300 |
| ASRS Report | 211249 |
| Person 2 | |
| Affiliation | company : air taxi |
| Function | flight crew : first officer |
| Qualification | pilot : instrument pilot : commercial |
| Events | |
| Anomaly | aircraft equipment problem : less severe non adherence : clearance other spatial deviation |
| Independent Detector | atc equipment other atc equipment : unspecified other controllera |
| Resolutory Action | flight crew : returned to intended course or assigned course flight crew : overcame equipment problem other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
On VOR approach to runway 17 required a significant side step after breaking out of the clouds. Tower asked if we had had trouble finding the runway. On the ground, both VOR systems checked normal, even with VLF selected off to avoid interface errors. After departure, we were cleared direct to medium large transport, and later told our track corrections, we found that the first officer had programmed the VLF's with incorrect initiation data. Once they were updated and corrected, navigation was normal for the balance of the trip to cvcr, and ATC did not need to correct any of our tracking. Separate problems, but in combination left us uncomfortable with the way we handled the trip. Lessons learned: discrepancies between #1 VOR-CDI and #2 VOR-CDI may not trigger the comparator warning. First officer must call out: in this case, #1 side was centered, #2 side was one DOT offset! Even over land, with VOR stations available, the VLF equipment should be programmed with challenge-response discipline. In this instance, the first officer set up the VLF's, while the captain checked the VOR's.
Original NASA ASRS Text
Title: FLC OF MDT ATX ACFT DEVIATED FROM ASSIGNED TRACK DUE TO ENTRY ERROR IN THE ACFT FLT NAV COMPUTER.
Narrative: ON VOR APCH TO RWY 17 REQUIRED A SIGNIFICANT SIDE STEP AFTER BREAKING OUT OF THE CLOUDS. TWR ASKED IF WE HAD HAD TROUBLE FINDING THE RWY. ON THE GND, BOTH VOR SYSTEMS CHKED NORMAL, EVEN WITH VLF SELECTED OFF TO AVOID INTERFACE ERRORS. AFTER DEP, WE WERE CLRED DIRECT TO MLG, AND LATER TOLD OUR TRACK CORRECTIONS, WE FOUND THAT THE FO HAD PROGRAMMED THE VLF'S WITH INCORRECT INITIATION DATA. ONCE THEY WERE UPDATED AND CORRECTED, NAV WAS NORMAL FOR THE BAL OF THE TRIP TO CVCR, AND ATC DID NOT NEED TO CORRECT ANY OF OUR TRACKING. SEPARATE PROBLEMS, BUT IN COMBINATION LEFT US UNCOMFORTABLE WITH THE WAY WE HANDLED THE TRIP. LESSONS LEARNED: DISCREPANCIES BTWN #1 VOR-CDI AND #2 VOR-CDI MAY NOT TRIGGER THE COMPARATOR WARNING. FO MUST CALL OUT: IN THIS CASE, #1 SIDE WAS CTRED, #2 SIDE WAS ONE DOT OFFSET! EVEN OVER LAND, WITH VOR STATIONS AVAILABLE, THE VLF EQUIP SHOULD BE PROGRAMMED WITH CHALLENGE-RESPONSE DISCIPLINE. IN THIS INSTANCE, THE FO SET UP THE VLF'S, WHILE THE CAPT CHKED THE VOR'S.
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.