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Visual separation in descent from same direction traffic. In proximity of traffic and TCASII did not provide an RA.
| Attributes | |
| ACN | 251533 |
| Time | |
| Date | 199309 |
| Day | Sat |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : cxr |
| State Reference | OH |
| Altitude | msl bound lower : 8800 msl bound upper : 9000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zob tower : den |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Flight Phase | descent other |
| Route In Use | approach : visual enroute : direct |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Light Transport, Low Wing, 2 Turboprop Eng |
| Navigation In Use | Other Other |
| Flight Phase | cruise other cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp pilot : flight engineer |
| Experience | flight time last 90 days : 170 flight time total : 5500 flight time type : 170 |
| ASRS Report | 251533 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | aircraft equipment problem : less severe other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other controllera |
| Resolutory Action | none taken : anomaly accepted |
| Consequence | faa : reviewed incident with flight crew |
| Miss Distance | horizontal : 12000 vertical : 200 |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Our next clearance was a vector of 090 degrees and descent to 6000 ft, just before the descent to 6000 ft, ZOB asked us if we had an light transport in sight at 2 O'clock at 9000 ft MSL. I acknowledged visual contact with the light transport and ZOB then said 'he will be climbing' and cleared us down to 6000 ft MSL, telling us to maintain visual separation with the light transport which we did. As we watched the light transport, it did not appear to be climbing. As we descended through 8800 ft MSL a TCASII display showed a green diamond with plus 200 above it at the edge of the 2 mi TCASII ring at 2 O'clock. We watched closely and saw no danger of collision since we were descending at 1000-1500 FPM. We wondered aloud why we did not get an RA and concluded that the TCASII computed no danger of conflict. After he had passed over and behind us, ZOB came on frequency and apologized to us, saying the light transport had told them they would be climbing and apparently did not do what the controller expected them to do. ZOB continued to vector us towards cle and apologized again. I am writing this report from very sparse notes 4 days after the incident so the desired precision and accuracy will not be what you would want. My major concern is that the controller's control techniques were flawed (he did not get confirmation that the light transport was climbing) and we were complacent and did not point out the light transport's apparent altitude sooner. We are looking into the TCASII manual and flight manual to see why the TCASII did not give us an RA in this situation.
Original NASA ASRS Text
Title: VISUAL SEPARATION IN DSCNT FROM SAME DIRECTION TFC. IN PROX OF TFC AND TCASII DID NOT PROVIDE AN RA.
Narrative: OUR NEXT CLRNC WAS A VECTOR OF 090 DEGS AND DSCNT TO 6000 FT, JUST BEFORE THE DSCNT TO 6000 FT, ZOB ASKED US IF WE HAD AN LTT IN SIGHT AT 2 O'CLOCK AT 9000 FT MSL. I ACKNOWLEDGED VISUAL CONTACT WITH THE LTT AND ZOB THEN SAID 'HE WILL BE CLBING' AND CLRED US DOWN TO 6000 FT MSL, TELLING US TO MAINTAIN VISUAL SEPARATION WITH THE LTT WHICH WE DID. AS WE WATCHED THE LTT, IT DID NOT APPEAR TO BE CLBING. AS WE DSNDED THROUGH 8800 FT MSL A TCASII DISPLAY SHOWED A GREEN DIAMOND WITH PLUS 200 ABOVE IT AT THE EDGE OF THE 2 MI TCASII RING AT 2 O'CLOCK. WE WATCHED CLOSELY AND SAW NO DANGER OF COLLISION SINCE WE WERE DSNDING AT 1000-1500 FPM. WE WONDERED ALOUD WHY WE DID NOT GET AN RA AND CONCLUDED THAT THE TCASII COMPUTED NO DANGER OF CONFLICT. AFTER HE HAD PASSED OVER AND BEHIND US, ZOB CAME ON FREQ AND APOLOGIZED TO US, SAYING THE LTT HAD TOLD THEM THEY WOULD BE CLBING AND APPARENTLY DID NOT DO WHAT THE CTLR EXPECTED THEM TO DO. ZOB CONTINUED TO VECTOR US TOWARDS CLE AND APOLOGIZED AGAIN. I AM WRITING THIS RPT FROM VERY SPARSE NOTES 4 DAYS AFTER THE INCIDENT SO THE DESIRED PRECISION AND ACCURACY WILL NOT BE WHAT YOU WOULD WANT. MY MAJOR CONCERN IS THAT THE CTLR'S CTL TECHNIQUES WERE FLAWED (HE DID NOT GET CONFIRMATION THAT THE LTT WAS CLBING) AND WE WERE COMPLACENT AND DID NOT POINT OUT THE LTT'S APPARENT ALT SOONER. WE ARE LOOKING INTO THE TCASII MANUAL AND FLT MANUAL TO SEE WHY THE TCASII DID NOT GIVE US AN RA IN THIS SIT.
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.