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A potential conflict occurred between a level SF340 at 6000 ft and a cruising C172 at 5500 ft, with the TCASII in the SF340 calling for a 'descend,' 10 NM southeast of TTT VORTAC, dfw, tx.
| Attributes | |
| ACN | 560691 |
| Time | |
| Date | 200209 |
| Day | Mon |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | navaid : ttt.vor |
| State Reference | TX |
| Altitude | msl bound lower : 5500 msl bound upper : 6000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : d10.tracon |
| Operator | common carrier : air carrier |
| Make Model Name | SF 340A |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent : intermediate altitude descent : approach |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | tracon : d10.tracon |
| Operator | general aviation : personal |
| Make Model Name | Skyhawk 172/Cutlass 172 |
| Operating Under FAR Part | Part 91 |
| Flight Phase | cruise : level |
| Flight Plan | VFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : multi engine pilot : flight engineer pilot : cfi pilot : atp |
| Experience | flight time last 90 days : 75 flight time total : 6000 flight time type : 1700 |
| ASRS Report | 560691 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Events | |
| Anomaly | aircraft equipment problem : critical conflict : airborne critical non adherence : required legal separation non adherence : published procedure other anomaly other |
| Independent Detector | aircraft equipment : tcas other flight crewa other flight crewb |
| Resolutory Action | flight crew : took evasive action flight crew : returned to assigned altitude other |
| Consequence | faa : reviewed incident with flight crew |
| Miss Distance | vertical : 500 |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance Airspace Structure Aircraft ATC Human Performance |
| Primary Problem | Aircraft |
| Air Traffic Incident | Operational Error |
Narrative:
Our TCASII issued a traffic alert. 1 O'clock position, +500 ft. Then it issued a 'descend' RA. We disengaged the autoplt and began a descent. After several seconds, we made visual contact with the intruder aircraft which was actually 500 ft below us! Had we not seen the intruder aircraft, the RA would have caused a midair or at least a near miss. We asked the controller to verify the intruder aircraft altitude. He did verify that his mode C indicated '500 ft below us and also stated that there was no aircraft above us for several mi.
Original NASA ASRS Text
Title: A POTENTIAL CONFLICT OCCURRED BTWN A LEVEL SF340 AT 6000 FT AND A CRUISING C172 AT 5500 FT, WITH THE TCASII IN THE SF340 CALLING FOR A 'DSND,' 10 NM SE OF TTT VORTAC, DFW, TX.
Narrative: OUR TCASII ISSUED A TFC ALERT. 1 O'CLOCK POS, +500 FT. THEN IT ISSUED A 'DSND' RA. WE DISENGAGED THE AUTOPLT AND BEGAN A DSCNT. AFTER SEVERAL SECONDS, WE MADE VISUAL CONTACT WITH THE INTRUDER ACFT WHICH WAS ACTUALLY 500 FT BELOW US! HAD WE NOT SEEN THE INTRUDER ACFT, THE RA WOULD HAVE CAUSED A MIDAIR OR AT LEAST A NEAR MISS. WE ASKED THE CTLR TO VERIFY THE INTRUDER ACFT ALT. HE DID VERIFY THAT HIS MODE C INDICATED '500 FT BELOW US AND ALSO STATED THAT THERE WAS NO ACFT ABOVE US FOR SEVERAL MI.
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.