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Potential conflict avoided by a combination of TCASII RA and ARTCC radar controller's vigilance in problem with clearance interpretation by flight crew. Descending traffic.
| Attributes | |
| ACN | 251443 |
| Time | |
| Date | 199309 |
| Day | Sun |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : yqo |
| State Reference | ON |
| Altitude | msl bound lower : 30800 msl bound upper : 31000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : zob |
| Operator | common carrier : air carrier |
| Make Model Name | Large Transport, Low Wing, 3 Turbojet Eng |
| Flight Phase | descent other |
| Route In Use | enroute : direct |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 200 flight time total : 19000 flight time type : 6000 |
| ASRS Report | 251443 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : flight engineer pilot : instrument pilot : atp pilot : cfi |
| Experience | flight time last 90 days : 200 flight time total : 6500 flight time type : 200 |
| ASRS Report | 251455 |
| Events | |
| Anomaly | altitude deviation : overshoot non adherence : clearance other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other controllera |
| Resolutory Action | controller : issued new clearance flight crew : took evasive action other |
| Consequence | faa : reviewed incident with flight crew |
| Miss Distance | horizontal : 36000 vertical : 1800 |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Flight from jfk to dtw was cleared to cross aylmer (yqo) at FL280. Flight continued to cruise at FL390. ZOB made a hurried call for flight to descend to FL310 'now' for crossing traffic. Descent was started and at FL315, a TA was issued by TCASII and at FL308 an RA was issued by TCASII. Flight was leveled off immediately and a look at the TCASII situation showed another aircraft at 9-10 O'clock 6-7 mi away. There was a discussion with ZOB and it appeared the controller had forgotten the clearance to cross yqo at FL280. In discussions with quality assurance at FAA the following day, they stated that after reviewing the tapes it was determined to be a controller error, but that it was not an incident because the aircraft, which were on approximately parallel courses, never were within 5 NM of each other. This miscom could have been prevented by either restating or repeating the clearance to cross aylmer at FL280 at the time the 'start descent now' call was made.
Original NASA ASRS Text
Title: POTENTIAL CONFLICT AVOIDED BY A COMBINATION OF TCASII RA AND ARTCC RADAR CTLR'S VIGILANCE IN PROB WITH CLRNC INTERP BY FLC. DSNDING TFC.
Narrative: FLT FROM JFK TO DTW WAS CLRED TO CROSS AYLMER (YQO) AT FL280. FLT CONTINUED TO CRUISE AT FL390. ZOB MADE A HURRIED CALL FOR FLT TO DSND TO FL310 'NOW' FOR XING TFC. DSCNT WAS STARTED AND AT FL315, A TA WAS ISSUED BY TCASII AND AT FL308 AN RA WAS ISSUED BY TCASII. FLT WAS LEVELED OFF IMMEDIATELY AND A LOOK AT THE TCASII SIT SHOWED ANOTHER ACFT AT 9-10 O'CLOCK 6-7 MI AWAY. THERE WAS A DISCUSSION WITH ZOB AND IT APPEARED THE CTLR HAD FORGOTTEN THE CLRNC TO CROSS YQO AT FL280. IN DISCUSSIONS WITH QUALITY ASSURANCE AT FAA THE FOLLOWING DAY, THEY STATED THAT AFTER REVIEWING THE TAPES IT WAS DETERMINED TO BE A CTLR ERROR, BUT THAT IT WAS NOT AN INCIDENT BECAUSE THE ACFT, WHICH WERE ON APPROX PARALLEL COURSES, NEVER WERE WITHIN 5 NM OF EACH OTHER. THIS MISCOM COULD HAVE BEEN PREVENTED BY EITHER RESTATING OR REPEATING THE CLRNC TO CROSS AYLMER AT FL280 AT THE TIME THE 'START DSCNT NOW' CALL WAS MADE.
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.