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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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A saab-340B crew descended in response to a TCASII command causing loss of separation with an aircraft below. There may have been an aircraft equipment problem TCASII false alarm. Evasive action descend.
| Attributes | |
| ACN | 364922 |
| Time | |
| Date | 199703 |
| Day | Sat |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : ads airport : dfw |
| State Reference | TX |
| Altitude | msl bound lower : 4000 msl bound upper : 4500 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : dfw |
| Operator | common carrier : air carrier |
| Make Model Name | SF 340B |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | cruise other cruise other |
| Route In Use | arrival other arrival star : star |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : cfi pilot : commercial pilot : instrument pilot : atp |
| Experience | flight time last 90 days : 200 flight time total : 3700 flight time type : 1500 |
| ASRS Report | 364922 |
| 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 : required legal separation |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other controllera other flight crewa |
| Resolutory Action | flight crew : took evasive action |
| Consequence | faa : reviewed incident with flight crew |
| Supplementary | |
| Primary Problem | Ambiguous |
| Air Traffic Incident | Operational Error |
Narrative:
We were at 4000 ft. Approach called traffic below us. We did not see him and responded 'looking.' we got an RA to descend. We told the controller that we were responding to an RA. He said 'no, stay at 4000 ft.' we said 'unable, responding to an RA.' he said 'you're responding to an RA?' we then were clear of conflict. We said we could go back to 4000 ft. Then he cleared us for the visual. When we got on the ground, we were asked to call TRACON and they explained that their separation had been broken and he would have to fill out a report. Callback conversation with reporter revealed the following information: the reporter flies the saab-340B. In the conversation with a TRACON supervisor, the reporter learned that the report that had to be filled in was an internal FAA report. The supervisor admitted that responding to the RA compromised separation on the aircraft below. The reporter did not see this aircraft or the one that caused the descend command. The reporter agrees that the descend commands may have been a false warning.
Original NASA ASRS Text
Title: A SAAB-340B CREW DSNDED IN RESPONSE TO A TCASII COMMAND CAUSING LOSS OF SEPARATION WITH AN ACFT BELOW. THERE MAY HAVE BEEN AN ACFT EQUIP PROB TCASII FALSE ALARM. EVASIVE ACTION DSND.
Narrative: WE WERE AT 4000 FT. APCH CALLED TFC BELOW US. WE DID NOT SEE HIM AND RESPONDED 'LOOKING.' WE GOT AN RA TO DSND. WE TOLD THE CTLR THAT WE WERE RESPONDING TO AN RA. HE SAID 'NO, STAY AT 4000 FT.' WE SAID 'UNABLE, RESPONDING TO AN RA.' HE SAID 'YOU'RE RESPONDING TO AN RA?' WE THEN WERE CLR OF CONFLICT. WE SAID WE COULD GO BACK TO 4000 FT. THEN HE CLRED US FOR THE VISUAL. WHEN WE GOT ON THE GND, WE WERE ASKED TO CALL TRACON AND THEY EXPLAINED THAT THEIR SEPARATION HAD BEEN BROKEN AND HE WOULD HAVE TO FILL OUT A RPT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR FLIES THE SAAB-340B. IN THE CONVERSATION WITH A TRACON SUPVR, THE RPTR LEARNED THAT THE RPT THAT HAD TO BE FILLED IN WAS AN INTERNAL FAA RPT. THE SUPVR ADMITTED THAT RESPONDING TO THE RA COMPROMISED SEPARATION ON THE ACFT BELOW. THE RPTR DID NOT SEE THIS ACFT OR THE ONE THAT CAUSED THE DSND COMMAND. THE RPTR AGREES THAT THE DSND COMMANDS MAY HAVE BEEN A FALSE 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.