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DC9 flight crew responded to another aircraft's clearance with a similar call sign by descending from assigned altitude.
| Attributes | |
| ACN | 531138 |
| Time | |
| Date | 200111 |
| Day | Tue |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | navaid : har.vortac |
| State Reference | PA |
| Altitude | msl single value : 9000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | tracon : mdt.tracon |
| Operator | common carrier : air carrier |
| Make Model Name | DC-9 30 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other vortac |
| Flight Phase | descent : intermediate altitude descent : approach |
| Route In Use | arrival : on vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | tracon : mdt.tracon |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent : approach |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : multi engine pilot : instrument pilot : commercial pilot : atp |
| Experience | flight time last 90 days : 60 flight time total : 6500 flight time type : 2500 |
| ASRS Report | 531138 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 70 flight time total : 5068 flight time type : 2867 |
| ASRS Report | 531137 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other |
| Independent Detector | atc equipment other atc equipment : radar other controllera other flight crewa |
| Resolutory Action | controller : issued alert controller : issued new clearance flight crew : returned to assigned altitude |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance ATC Human Performance |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
We had been level at 9000 ft MSL and accepted what we thought was a clearance for us to descend to 4000 ft MSL. Another aircraft, known as 'aircraft Y', voiced a concern to ATC that we may have inadvertently accepted their clearance to 4000 ft MSL. The controller then gave us a new altitude to descend to, that being 6000 ft. We had been at 8600 ft MSL (out of 9000 ft MSL) when aircraft Y voiced concern, at which point we ceased our descent, and returned to 9000 ft. When ATC clarified our new assigned altitude of 6000 ft MSL, we descended to that altitude. There was confusion on my part due to another aircraft on same frequency with a similar call sign. There was no advisory to us that such a flight existed, which may have made me more attentive. I was trying to identify, aurally, the localizer for the captain, who was flying this leg. Also I was going to identify navigation 2, which had recently been tuned to harrisburg VOR. I also feel that fatigue may have contributed to this situation, as I had slept approximately 5 1/2 hours, prior to this duty period.
Original NASA ASRS Text
Title: DC9 FLC RESPONDED TO ANOTHER ACFT'S CLRNC WITH A SIMILAR CALL SIGN BY DSNDING FROM ASSIGNED ALT.
Narrative: WE HAD BEEN LEVEL AT 9000 FT MSL AND ACCEPTED WHAT WE THOUGHT WAS A CLRNC FOR US TO DSND TO 4000 FT MSL. ANOTHER ACFT, KNOWN AS 'ACFT Y', VOICED A CONCERN TO ATC THAT WE MAY HAVE INADVERTENTLY ACCEPTED THEIR CLRNC TO 4000 FT MSL. THE CTLR THEN GAVE US A NEW ALT TO DSND TO, THAT BEING 6000 FT. WE HAD BEEN AT 8600 FT MSL (OUT OF 9000 FT MSL) WHEN ACFT Y VOICED CONCERN, AT WHICH POINT WE CEASED OUR DSCNT, AND RETURNED TO 9000 FT. WHEN ATC CLARIFIED OUR NEW ASSIGNED ALT OF 6000 FT MSL, WE DSNDED TO THAT ALT. THERE WAS CONFUSION ON MY PART DUE TO ANOTHER ACFT ON SAME FREQ WITH A SIMILAR CALL SIGN. THERE WAS NO ADVISORY TO US THAT SUCH A FLT EXISTED, WHICH MAY HAVE MADE ME MORE ATTENTIVE. I WAS TRYING TO IDENT, AURALLY, THE LOC FOR THE CAPT, WHO WAS FLYING THIS LEG. ALSO I WAS GOING TO IDENT NAV 2, WHICH HAD RECENTLY BEEN TUNED TO HARRISBURG VOR. I ALSO FEEL THAT FATIGUE MAY HAVE CONTRIBUTED TO THIS SIT, AS I HAD SLEPT APPROX 5 1/2 HRS, PRIOR TO THIS DUTY PERIOD.
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.