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IFR aircraft was allowed to descend below minimum vector altitude and flew 600' above ground obstruction antenna. Operational error.
| Attributes | |
| ACN | 85769 |
| Time | |
| Date | 198804 |
| Day | Tue |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : fsd |
| State Reference | SD |
| Altitude | msl bound lower : 4000 msl bound upper : 4400 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : fsd |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Flight Phase | cruise other descent : approach descent other |
| Route In Use | enroute : on vectors enroute airway : fsd |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : approach |
| Qualification | controller : radar |
| Experience | controller non radar : 1 controller radar : 5 |
| ASRS Report | 85769 |
| Person 2 | |
| Function | flight crew : single pilot |
| Qualification | pilot : instrument |
| Events | |
| Anomaly | altitude deviation : overshoot other anomaly other other spatial deviation |
| Independent Detector | other controllera |
| Resolutory Action | none taken : detected after the fact |
| Consequence | faa : investigated |
| Miss Distance | horizontal : 0 vertical : 600 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
While working approach control (combined with departure and handoff/flight data), I descended an arrival IFR aircraft to 4400' at pilot's discretion from 6000'. I thought the pilot read back 4400', but instead he read back 4000'. Center had had a computer failure, and all IFR flts, both active and inactive, were having to be re-entered to the computer and verified, making an extra workload and distraction for all. This aircraft was the third I received a handoff on that I did not have any flight progress strip on. I was also working 7 other aircraft at the time, both VFR and IFR. The aircraft descended to 4000', which was 400' below the MVA over an antenna. The WX was not a factor, with scattered cirrus and visibility 15 mi. Lesson, don't allow other factors to distract from primary responsibility of controling, and listen to readbacks.
Original NASA ASRS Text
Title: IFR ACFT WAS ALLOWED TO DESCEND BELOW MINIMUM VECTOR ALT AND FLEW 600' ABOVE GND OBSTRUCTION ANTENNA. OPERATIONAL ERROR.
Narrative: WHILE WORKING APCH CTL (COMBINED WITH DEP AND HDOF/FLT DATA), I DSNDED AN ARR IFR ACFT TO 4400' AT PLT'S DISCRETION FROM 6000'. I THOUGHT THE PLT READ BACK 4400', BUT INSTEAD HE READ BACK 4000'. CENTER HAD HAD A COMPUTER FAILURE, AND ALL IFR FLTS, BOTH ACTIVE AND INACTIVE, WERE HAVING TO BE RE-ENTERED TO THE COMPUTER AND VERIFIED, MAKING AN EXTRA WORKLOAD AND DISTR FOR ALL. THIS ACFT WAS THE THIRD I RECEIVED A HDOF ON THAT I DID NOT HAVE ANY FLT PROGRESS STRIP ON. I WAS ALSO WORKING 7 OTHER ACFT AT THE TIME, BOTH VFR AND IFR. THE ACFT DSNDED TO 4000', WHICH WAS 400' BELOW THE MVA OVER AN ANTENNA. THE WX WAS NOT A FACTOR, WITH SCATTERED CIRRUS AND VIS 15 MI. LESSON, DON'T ALLOW OTHER FACTORS TO DISTRACT FROM PRIMARY RESPONSIBILITY OF CTLING, AND LISTEN TO READBACKS.
Data retrieved from NASA's ASRS site as of August 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.