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High precession of directional gyro at high rate causes small aircraft making NDB approach in IMC to go off track and do missed approach.
| Attributes | |
| ACN | 151307 |
| Time | |
| Date | 199007 |
| Day | Wed |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : cle |
| State Reference | OH |
| Altitude | msl bound lower : 3000 msl bound upper : 3000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : cle |
| Operator | general aviation : personal |
| Make Model Name | Small Aircraft, High Wing, 1 Eng, Fixed Gear |
| Flight Phase | descent : approach landing : missed approach |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | Other |
| Function | flight crew : single pilot |
| Qualification | pilot : atp pilot : instrument pilot : cfi |
| Experience | flight time last 90 days : 15 flight time total : 7950 flight time type : 5000 |
| ASRS Report | 151307 |
| Person 2 | |
| Affiliation | government : faa |
| Function | controller : approach |
| Qualification | controller : radar |
| Events | |
| Anomaly | aircraft equipment problem : critical non adherence : clearance other spatial deviation |
| Independent Detector | other controllera |
| Resolutory Action | none taken : detected after the fact other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
On the NDB 23R approach, my instruments showed I was established outbnd from the beacon on the 237 degree right to the runway. The approach controller stated I was right of course and proceeded to vector me around for another approach. I followed all instructions the controller gave me. Just prior to being cleared for the approach, I had reset my directional gyro with the compass; after being pulled off the approach I found my directional gyro in error of more than 30 degrees, this error occurred in less than 5 mins. I had to keep resetting the gyro approximately every 2 min for it was processing more than 10 degrees in that short amount of time. Once on the ground I reported the excessive amount of error in the directional gyro to the operator of the aircraft. He had the instrument removed and overhauled before the next flight. I recommend gyroscope instruments have a mandatory overhaul schedule if used for instrument flying.
Original NASA ASRS Text
Title: HIGH PRECESSION OF DIRECTIONAL GYRO AT HIGH RATE CAUSES SMA MAKING NDB APCH IN IMC TO GO OFF TRACK AND DO MISSED APCH.
Narrative: ON THE NDB 23R APCH, MY INSTRUMENTS SHOWED I WAS ESTABLISHED OUTBND FROM THE BEACON ON THE 237 DEG R TO THE RWY. THE APCH CTLR STATED I WAS R OF COURSE AND PROCEEDED TO VECTOR ME AROUND FOR ANOTHER APCH. I FOLLOWED ALL INSTRUCTIONS THE CTLR GAVE ME. JUST PRIOR TO BEING CLRED FOR THE APCH, I HAD RESET MY DIRECTIONAL GYRO WITH THE COMPASS; AFTER BEING PULLED OFF THE APCH I FOUND MY DIRECTIONAL GYRO IN ERROR OF MORE THAN 30 DEGS, THIS ERROR OCCURRED IN LESS THAN 5 MINS. I HAD TO KEEP RESETTING THE GYRO APPROX EVERY 2 MIN FOR IT WAS PROCESSING MORE THAN 10 DEGS IN THAT SHORT AMOUNT OF TIME. ONCE ON THE GND I RPTED THE EXCESSIVE AMOUNT OF ERROR IN THE DIRECTIONAL GYRO TO THE OPERATOR OF THE ACFT. HE HAD THE INSTRUMENT REMOVED AND OVERHAULED BEFORE THE NEXT FLT. I RECOMMEND GYROSCOPE INSTRUMENTS HAVE A MANDATORY OVERHAUL SCHEDULE IF USED FOR INSTRUMENT FLYING.
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.