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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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After being instructed to descend and maintain visual separation from a carj aircraft at 12000 ft by a ZOB radar controller, a B737 crew lost sight of the aircraft and received a TCASII alert.
| Attributes | |
| ACN | 609617 |
| Time | |
| Date | 200402 |
| Day | Sat |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : zob.artcc |
| State Reference | OH |
| Altitude | msl bound lower : 12000 msl bound upper : 13000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Dusk |
| Aircraft 1 | |
| Controlling Facilities | artcc : zob.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent : intermediate altitude descent : vacating altitude |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | artcc : zob.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | Regional Jet CL65, Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise : level |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Experience | flight time last 90 days : 200 flight time total : 12000 flight time type : 4000 |
| ASRS Report | 609617 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Events | |
| Anomaly | conflict : airborne critical non adherence : required legal separation non adherence : clearance |
| Independent Detector | atc equipment other atc equipment : radar mode c aircraft equipment : tcas other controllera other flight crewa other flight crewb other other : 3 |
| Resolutory Action | flight crew : took evasive action |
| Supplementary | |
| Problem Areas | ATC Human Performance Flight Crew Human Performance |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Level at 13000 ft, ATC reported traffic at 1 O'clock position below us at 12000 ft, I believe. It was a small regional jet. Captain reported traffic and then I saw the traffic. Captain told ATC we could maintain visual separation. ATC gave us a clearance to 10000 ft and to maintain visual separation. I believed I could descend quickly through the altitude of the traffic. I entered 'level change' mode but the aircraft did not respond quickly enough. I took my eyes off the traffic to enter 'vertical speed' mode which gives a much faster descent rate. I then lost track of the traffic. Shortly thereafter TCASII gave us a traffic alert followed fairly quickly by an RA. I quickly followed the command prompts to climb and in short order we were clear of the traffic. Moral of the story: never accept an en route clearance to maintain visual separation unless you are on an obvious divergent track.
Original NASA ASRS Text
Title: AFTER BEING INSTRUCTED TO DSND AND MAINTAIN VISUAL SEPARATION FROM A CARJ ACFT AT 12000 FT BY A ZOB RADAR CTLR, A B737 CREW LOST SIGHT OF THE ACFT AND RECEIVED A TCASII ALERT.
Narrative: LEVEL AT 13000 FT, ATC RPTED TFC AT 1 O'CLOCK POS BELOW US AT 12000 FT, I BELIEVE. IT WAS A SMALL REGIONAL JET. CAPT RPTED TFC AND THEN I SAW THE TFC. CAPT TOLD ATC WE COULD MAINTAIN VISUAL SEPARATION. ATC GAVE US A CLRNC TO 10000 FT AND TO MAINTAIN VISUAL SEPARATION. I BELIEVED I COULD DSND QUICKLY THROUGH THE ALT OF THE TFC. I ENTERED 'LEVEL CHANGE' MODE BUT THE ACFT DID NOT RESPOND QUICKLY ENOUGH. I TOOK MY EYES OFF THE TFC TO ENTER 'VERT SPD' MODE WHICH GIVES A MUCH FASTER DSCNT RATE. I THEN LOST TRACK OF THE TFC. SHORTLY THEREAFTER TCASII GAVE US A TFC ALERT FOLLOWED FAIRLY QUICKLY BY AN RA. I QUICKLY FOLLOWED THE COMMAND PROMPTS TO CLB AND IN SHORT ORDER WE WERE CLR OF THE TFC. MORAL OF THE STORY: NEVER ACCEPT AN ENRTE CLRNC TO MAINTAIN VISUAL SEPARATION UNLESS YOU ARE ON AN OBVIOUS DIVERGENT TRACK.
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.