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A TCASII RA is issued on traffic for a B777 that had descended towards the wrong altitude without a clearance acknowledgement by the flight crew after passing bittr intersection, mi.
| Attributes | |
| ACN | 599208 |
| Time | |
| Date | 200311 |
| Day | Mon |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | intersection : bittr |
| State Reference | MI |
| Altitude | msl bound lower : 23000 msl bound upper : 26000 |
| Environment | |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zau.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B777 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other other |
| Flight Phase | descent : intermediate altitude |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | artcc : zau.artcc |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| ASRS Report | 599208 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Events | |
| Anomaly | altitude deviation : overshoot conflict : airborne critical non adherence : clearance non adherence : published procedure non adherence : required legal separation other anomaly other |
| Independent Detector | atc equipment : conflict alert aircraft equipment : tcas other controllera |
| Resolutory Action | controller : issued new clearance controller : separated traffic flight crew : returned to assigned altitude |
| Consequence | faa : investigated faa : reviewed incident with flight crew |
| Supplementary | |
| Problem Areas | Environmental Factor Airspace Structure Flight Crew Human Performance ATC Human Performance |
| Primary Problem | Ambiguous |
| Air Traffic Incident | Pilot Deviation Operational Error |
Narrative:
Location: bittr intersection, and began descent. Captain was on PA did not hear clearance. Relief pilot was involved with other duties, but thinks clearance was indeed to FL240. Passing FL247 controller said we were supposed to be at FL260. Captain asked whether to climb back to FL260. Controller said climb now, climb to FL250, then said, descend to FL230. Meanwhile TCASII RA annunciated climb, but controller emphasized descent, as visual contact was established. Decision to continue descent was made without further incident. Contacted ATC upon arrival. Their internal investigation suggested the scenario where clearance was issued, but not acknowledged resulting in temporary loss of separation. Pilot procedure may have broken down, but cannot pinpoint cause for not hearing revised clearance, if it was issued, as we were all engaged in separate duties at the critical moment. Follow up call from ATC manager that flight crew not at fault. No further action to result from this incident.
Original NASA ASRS Text
Title: A TCASII RA IS ISSUED ON TFC FOR A B777 THAT HAD DSNDED TOWARDS THE WRONG ALT WITHOUT A CLRNC ACKNOWLEDGEMENT BY THE FLT CREW AFTER PASSING BITTR INTXN, MI.
Narrative: LOCATION: BITTR INTXN, AND BEGAN DSCNT. CAPT WAS ON PA DID NOT HEAR CLRNC. RELIEF PLT WAS INVOLVED WITH OTHER DUTIES, BUT THINKS CLRNC WAS INDEED TO FL240. PASSING FL247 CTLR SAID WE WERE SUPPOSED TO BE AT FL260. CAPT ASKED WHETHER TO CLB BACK TO FL260. CTLR SAID CLB NOW, CLB TO FL250, THEN SAID, DSND TO FL230. MEANWHILE TCASII RA ANNUNCIATED CLB, BUT CTLR EMPHASIZED DSCNT, AS VISUAL CONTACT WAS ESTABLISHED. DECISION TO CONTINUE DSCNT WAS MADE WITHOUT FURTHER INCIDENT. CONTACTED ATC UPON ARR. THEIR INTERNAL INVESTIGATION SUGGESTED THE SCENARIO WHERE CLRNC WAS ISSUED, BUT NOT ACKNOWLEDGED RESULTING IN TEMPORARY LOSS OF SEPARATION. PLT PROC MAY HAVE BROKEN DOWN, BUT CANNOT PINPOINT CAUSE FOR NOT HEARING REVISED CLRNC, IF IT WAS ISSUED, AS WE WERE ALL ENGAGED IN SEPARATE DUTIES AT THE CRITICAL MOMENT. FOLLOW UP CALL FROM ATC MGR THAT FLT CREW NOT AT FAULT. NO FURTHER ACTION TO RESULT FROM THIS INCIDENT.
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.