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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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DHC8 at temporary cruise altitude, TCASII RA to climb just as ATC cleared aircraft to descend. Flight crew followed TCASII to avoid intruder aircraft while advising ATC. Controller cleared aircraft to higher altitude shortly thereafter.
| Attributes | |
| ACN | 352410 |
| Time | |
| Date | 199611 |
| Day | Tue |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : yyz |
| State Reference | ON |
| Altitude | msl bound lower : 3000 msl bound upper : 3700 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : yyz |
| Operator | common carrier : air carrier |
| Make Model Name | Dash 8-100 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 250 flight time total : 25000 flight time type : 10000 |
| ASRS Report | 352410 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 240 flight time type : 3600 |
| ASRS Report | 353286 |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : required legal separation other anomaly other |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : took evasive action |
| Consequence | Other |
| Miss Distance | horizontal : 5000 vertical : 0 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
While level at 3000 ft on vectors, the following events occurred in rapid succession as follows: 1) TA, 12 O'clock, 100 ft below, inside TCASII inner ring. 2) my visual sighting of traffic at 12 O'clock at my altitude, crossing left to right. 3) RA 'climb, climb now.' 4) ATC instruction to descend to 2000 ft. As we had begun to comply with the RA 'climb' instruction, I continued the climb, after the ATC instructed to descend. I instructed my first officer to so inform ATC. After the TCASII announced 'clear of conflict,' I leveled at approximately 3700 ft, and queried ATC for further instructions, whereupon we were cleared to 5000 ft. This incident was a controller error, but it presented me with a dilemma, namely the conflicting mandates of the RA instruction and the ATC instruction. Given the same situation again I would react as I did, as it seemed the safest course.
Original NASA ASRS Text
Title: DHC8 AT TEMPORARY CRUISE ALT, TCASII RA TO CLB JUST AS ATC CLRED ACFT TO DSND. FLC FOLLOWED TCASII TO AVOID INTRUDER ACFT WHILE ADVISING ATC. CTLR CLRED ACFT TO HIGHER ALT SHORTLY THEREAFTER.
Narrative: WHILE LEVEL AT 3000 FT ON VECTORS, THE FOLLOWING EVENTS OCCURRED IN RAPID SUCCESSION AS FOLLOWS: 1) TA, 12 O'CLOCK, 100 FT BELOW, INSIDE TCASII INNER RING. 2) MY VISUAL SIGHTING OF TFC AT 12 O'CLOCK AT MY ALT, XING L TO R. 3) RA 'CLB, CLB NOW.' 4) ATC INSTRUCTION TO DSND TO 2000 FT. AS WE HAD BEGUN TO COMPLY WITH THE RA 'CLB' INSTRUCTION, I CONTINUED THE CLB, AFTER THE ATC INSTRUCTED TO DSND. I INSTRUCTED MY FO TO SO INFORM ATC. AFTER THE TCASII ANNOUNCED 'CLR OF CONFLICT,' I LEVELED AT APPROX 3700 FT, AND QUERIED ATC FOR FURTHER INSTRUCTIONS, WHEREUPON WE WERE CLRED TO 5000 FT. THIS INCIDENT WAS A CTLR ERROR, BUT IT PRESENTED ME WITH A DILEMMA, NAMELY THE CONFLICTING MANDATES OF THE RA INSTRUCTION AND THE ATC INSTRUCTION. GIVEN THE SAME SIT AGAIN I WOULD REACT AS I DID, AS IT SEEMED THE SAFEST COURSE.
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.