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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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Approach controller inadvertently descended a B737 through the altitude of a VFR C210 who was opposite direction traffic. Due to other duties the controller did not give either aircraft TA's and the B737 responded to a TCASII RA to avoid the C210.
| Attributes | |
| ACN | 367521 |
| Time | |
| Date | 199704 |
| Day | Sun |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : bld airport : las |
| State Reference | NV |
| Altitude | msl bound lower : 10500 msl bound upper : 10700 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : las |
| Operator | common carrier : air carrier |
| Make Model Name | B737-200 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other |
| Flight Phase | descent other |
| Route In Use | arrival other arrival star : star enroute airway : las |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | general aviation : personal |
| Make Model Name | Cessna 210 Centurion / Turbo Centurion 210C, 210D |
| Operating Under FAR Part | Part 91 |
| Flight Phase | cruise other |
| Flight Plan | VFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : approach |
| Qualification | controller : radar |
| Experience | controller military : 4 controller radar : 19 |
| ASRS Report | 367521 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | conflict : nmac non adherence : published procedure other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | flight crew : took evasive action |
| Consequence | Other |
| Miss Distance | vertical : 490 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
Aircraft #1 was inbound on the creso arrival at 12000 ft. Aircraft #2 was VFR en route, opposite direction to aircraft #1, at 10500 ft. Distance between both aircraft was approximately 12 mi. Aircraft #1 was issued descent clearance to 11000 ft. Traffic was not exchanged due to higher priority duties. Approximately 2 mins later, aircraft #1 reported they were responding to a TCASII RA, and that an near midair collision had just occurred. After listening to the tape, I realized that I had in fact issued aircraft #1 a descent clearance to 10000 ft, and the pilot read back 10000 ft. Yet in my mind I was assured I had issued 11000 ft, due to the opposite direction traffic. Causal factors: 1) ineffective listening. 2) hearback versus readback. 3) additional duties workload (required pointouts to other sectors).
Original NASA ASRS Text
Title: APCH CTLR INADVERTENTLY DSNDED A B737 THROUGH THE ALT OF A VFR C210 WHO WAS OPPOSITE DIRECTION TFC. DUE TO OTHER DUTIES THE CTLR DID NOT GIVE EITHER ACFT TA'S AND THE B737 RESPONDED TO A TCASII RA TO AVOID THE C210.
Narrative: ACFT #1 WAS INBOUND ON THE CRESO ARR AT 12000 FT. ACFT #2 WAS VFR ENRTE, OPPOSITE DIRECTION TO ACFT #1, AT 10500 FT. DISTANCE BTWN BOTH ACFT WAS APPROX 12 MI. ACFT #1 WAS ISSUED DSCNT CLRNC TO 11000 FT. TFC WAS NOT EXCHANGED DUE TO HIGHER PRIORITY DUTIES. APPROX 2 MINS LATER, ACFT #1 RPTED THEY WERE RESPONDING TO A TCASII RA, AND THAT AN NMAC HAD JUST OCCURRED. AFTER LISTENING TO THE TAPE, I REALIZED THAT I HAD IN FACT ISSUED ACFT #1 A DSCNT CLRNC TO 10000 FT, AND THE PLT READ BACK 10000 FT. YET IN MY MIND I WAS ASSURED I HAD ISSUED 11000 FT, DUE TO THE OPPOSITE DIRECTION TFC. CAUSAL FACTORS: 1) INEFFECTIVE LISTENING. 2) HEARBACK VERSUS READBACK. 3) ADDITIONAL DUTIES WORKLOAD (REQUIRED POINTOUTS TO OTHER SECTORS).
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.