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Air carrier X descent to occupied altitude due to readback hearback error had less than standard separation from small aircraft Y. System error.
| Attributes | |
| ACN | 264523 |
| Time | |
| Date | 199402 |
| Day | Sun |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : sat |
| State Reference | TX |
| Altitude | msl bound lower : 5000 msl bound upper : 5000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : sat |
| Operator | common carrier : air carrier |
| Make Model Name | MD-88 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | cruise other descent other |
| Route In Use | enroute : direct |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | general aviation : personal |
| Make Model Name | Cheetah, Tiger, Traveler |
| Operating Under FAR Part | Part 91 |
| Flight Phase | climbout : intermediate altitude |
| Route In Use | enroute : direct |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : approach |
| Qualification | controller : radar |
| Experience | controller non radar : 3 controller radar : 7 |
| ASRS Report | 264523 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : overshoot conflict : airborne less severe non adherence : published procedure non adherence : clearance non adherence : required legal separation |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified |
| Resolutory Action | flight crew : took evasive action |
| Consequence | faa : investigated |
| Miss Distance | horizontal : 6000 vertical : 200 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
During readback of descent clearance, air carrier X MD88 read back incorrect altitude. Controller did not hear readback because of coordination blocking it out. MD88 descended to 5000 ft with small aircraft Y (AA5) climbing cut on converging course to 5000 ft. Approximately 2 mi and 300 ft apart, controller saw situation, turned the MD88 away from traffic and climbed to 6000 ft. At this time, MD88 advised receiving a TCASII alert and was making the turn and climbing. TCASII parameters should have alerted pilot earlier, but for some reason didn't. Controller was extremely busy, and because he missed the readback assumed the MD88 would level off at 6000 ft. Obviously, all concerned must pay extra diligence during readback/hearback exchanges to make sure what was said was heard.
Original NASA ASRS Text
Title: ACR X DSCNT TO OCCUPIED ALT DUE TO READBACK HEARBACK ERROR HAD LTSS FROM SMA Y. SYS ERROR.
Narrative: DURING READBACK OF DSCNT CLRNC, ACR X MD88 READ BACK INCORRECT ALT. CTLR DID NOT HEAR READBACK BECAUSE OF COORD BLOCKING IT OUT. MD88 DSNDED TO 5000 FT WITH SMA Y (AA5) CLBING CUT ON CONVERGING COURSE TO 5000 FT. APPROX 2 MI AND 300 FT APART, CTLR SAW SIT, TURNED THE MD88 AWAY FROM TFC AND CLBED TO 6000 FT. AT THIS TIME, MD88 ADVISED RECEIVING A TCASII ALERT AND WAS MAKING THE TURN AND CLBING. TCASII PARAMETERS SHOULD HAVE ALERTED PLT EARLIER, BUT FOR SOME REASON DIDN'T. CTLR WAS EXTREMELY BUSY, AND BECAUSE HE MISSED THE READBACK ASSUMED THE MD88 WOULD LEVEL OFF AT 6000 FT. OBVIOUSLY, ALL CONCERNED MUST PAY EXTRA DILIGENCE DURING READBACK/HEARBACK EXCHANGES TO MAKE SURE WHAT WAS SAID WAS HEARD.
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.