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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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Air carrier descending to 10000 ft receives TCASII RA to continue descent. ATC issues traffic below climbing to 9000 ft. Air carrier pilot thinks TCASII is unsafe in visual conditions.
| Attributes | |
| ACN | 240081 |
| Time | |
| Date | 199304 |
| Day | Thu |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : lax |
| State Reference | CA |
| Altitude | msl bound lower : 9500 msl bound upper : 10000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : lax |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Flight Phase | descent other |
| Route In Use | arrival other enroute : on vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Flight Phase | climbout : initial |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 400 flight time total : 6000 flight time type : 2500 |
| ASRS Report | 240081 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : overshoot non adherence : clearance other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | flight crew : took evasive action |
| Consequence | Other |
| Miss Distance | horizontal : 0 vertical : 1000 |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation other |
Narrative:
On descent we were cleared to 10000 ft. When passing through about 10500 ft the TCASII began to insist on a descent, increase descent. Because of TCASII loud voice, first officer did not hear approach state that traffic would level 1000 ft below us, so he followed TCASII direction, flying through 10000 ft. Captain was talking to center when evasive action started. In the 5-10 seconds it took to discern what was happening, the aircraft had flown down to about 9500 ft. Immediate recovery was initiated. I will never follow TCASII instructions again in VMC, since a midair collision would have resulted from these TCASII advisories. The TCASII volume being far louder than ATC is a hazard, as it can (and just did) override ATC instructions.
Original NASA ASRS Text
Title: ACR DSNDING TO 10000 FT RECEIVES TCASII RA TO CONTINUE DSCNT. ATC ISSUES TFC BELOW CLBING TO 9000 FT. ACR PLT THINKS TCASII IS UNSAFE IN VISUAL CONDITIONS.
Narrative: ON DSCNT WE WERE CLRED TO 10000 FT. WHEN PASSING THROUGH ABOUT 10500 FT THE TCASII BEGAN TO INSIST ON A DSCNT, INCREASE DSCNT. BECAUSE OF TCASII LOUD VOICE, FO DID NOT HEAR APCH STATE THAT TFC WOULD LEVEL 1000 FT BELOW US, SO HE FOLLOWED TCASII DIRECTION, FLYING THROUGH 10000 FT. CAPT WAS TALKING TO CTR WHEN EVASIVE ACTION STARTED. IN THE 5-10 SECONDS IT TOOK TO DISCERN WHAT WAS HAPPENING, THE ACFT HAD FLOWN DOWN TO ABOUT 9500 FT. IMMEDIATE RECOVERY WAS INITIATED. I WILL NEVER FOLLOW TCASII INSTRUCTIONS AGAIN IN VMC, SINCE A MIDAIR COLLISION WOULD HAVE RESULTED FROM THESE TCASII ADVISORIES. THE TCASII VOLUME BEING FAR LOUDER THAN ATC IS A HAZARD, AS IT CAN (AND JUST DID) OVERRIDE ATC INSTRUCTIONS.
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.