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Close proximity air carrier-large transport GA-small aircraft after start of descent also flight crew reversed descent in response to TCASII RA.
| Attributes | |
| ACN | 191968 |
| Time | |
| Date | 199110 |
| Day | Tue |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : den |
| State Reference | CO |
| Altitude | msl bound lower : 16500 msl bound upper : 17000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdv |
| Operator | common carrier : air carrier |
| Make Model Name | Large Transport, Low Wing, 3 Turbojet Eng |
| Flight Phase | descent other |
| Route In Use | enroute airway : zdv |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Flight Phase | cruise other |
| Flight Plan | VFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp pilot : flight engineer |
| Experience | flight time last 90 days : 200 flight time total : 7000 flight time type : 1300 |
| ASRS Report | 191968 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified |
| Resolutory Action | flight crew : took evasive action |
| Consequence | Other |
| Miss Distance | horizontal : 2500 vertical : 100 |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | other |
Narrative:
Over kiowa VOR my flight was cleared from 17000 ft to maintain 11000 ft. We left 17000 ft and immediately received a TCASII TA, followed with 5 second by an RA. All indications were that we passed within 1/2 mi at the same altitude as the target aircraft. After the incident, center said it was a VFR aircraft at 16500 ft. We followed the TCASII RA and climbed to 17500 ft before we again descended into denver. I can only assume that the target mode C was off or intermittent which was why neither the controller nor the TCASII gave us an earlier warning.
Original NASA ASRS Text
Title: CLOSE PROX ACR-LGT GA-SMA AFTER START OF DSCNT ALSO FLC REVERSED DSCNT IN RESPONSE TO TCASII RA.
Narrative: OVER KIOWA VOR MY FLT WAS CLRED FROM 17000 FT TO MAINTAIN 11000 FT. WE LEFT 17000 FT AND IMMEDIATELY RECEIVED A TCASII TA, FOLLOWED WITH 5 SEC BY AN RA. ALL INDICATIONS WERE THAT WE PASSED WITHIN 1/2 MI AT THE SAME ALT AS THE TARGET ACFT. AFTER THE INCIDENT, CENTER SAID IT WAS A VFR ACFT AT 16500 FT. WE FOLLOWED THE TCASII RA AND CLBED TO 17500 FT BEFORE WE AGAIN DSNDED INTO DENVER. I CAN ONLY ASSUME THAT THE TARGET MODE C WAS OFF OR INTERMITTENT WHICH WAS WHY NEITHER THE CTLR NOR THE TCASII GAVE US AN EARLIER WARNING.
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.