<< >> NASA ASRS Report 303925, May 1995

An initial call sign mix-up may have contributed to an incorrect clearance copy. Flight crew's readback went uncorrected, and air carrier overshot altitude in descent. Loss of separation resulted.

Attributes
ACN	303925
Time
Date	199505
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : clt
State Reference	NC
Altitude	msl bound lower : 10400 msl bound upper : 11000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : ztl
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	descent other
Route In Use	arrival other arrival star : star enroute airway : ztl
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Dash 8 Series Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent 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 : instrument pilot : flight engineer pilot : commercial pilot : atp
Experience	flight time last 90 days : 200 flight time total : 12000 flight time type : 3100
ASRS Report	303925
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : overshoot conflict : airborne less severe non adherence : required legal separation non adherence : clearance other anomaly other
Independent Detector	other flight crewa
Resolutory Action	other
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 9000 vertical : 500
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Initial call sign mix-up between same company xyz and zyx. Descent clearance was read back to ZTL as 10000 ft, 250 KTS at fix. At 11000 ft we saw dash 8 commuter off left wing 1-2 mi and slightly below. We rechked altitude alert setting as 10000 ft and leveled at 10400 ft to 10500 ft above and right of dash 8. It became obvious (ZTL called us) that the commuter was level at 10000 ft and we were below the altitude that ATC thought they issued 11000 ft. We called a visual and continued with 500 ft separation. After the flight the tapes were checked and although ZTL issued a clearance to 11000 ft we read back 10000 ft, 250 KTS, and were never corrected. We both pointed to the set altitude prior to the descent and followed all other required procedures. The initial call sign mix-up may have contributed to the error. Captain was flying and first officer was on the radios.

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Original NASA ASRS Text

Title: AN INITIAL CALL SIGN MIX-UP MAY HAVE CONTRIBUTED TO AN INCORRECT CLRNC COPY. FLC'S READBACK WENT UNCORRECTED, AND ACR OVERSHOT ALT IN DSCNT. LOSS OF SEPARATION RESULTED.

Narrative: INITIAL CALL SIGN MIX-UP BTWN SAME COMPANY XYZ AND ZYX. DSCNT CLRNC WAS READ BACK TO ZTL AS 10000 FT, 250 KTS AT FIX. AT 11000 FT WE SAW DASH 8 COMMUTER OFF L WING 1-2 MI AND SLIGHTLY BELOW. WE RECHKED ALT ALERT SETTING AS 10000 FT AND LEVELED AT 10400 FT TO 10500 FT ABOVE AND R OF DASH 8. IT BECAME OBVIOUS (ZTL CALLED US) THAT THE COMMUTER WAS LEVEL AT 10000 FT AND WE WERE BELOW THE ALT THAT ATC THOUGHT THEY ISSUED 11000 FT. WE CALLED A VISUAL AND CONTINUED WITH 500 FT SEPARATION. AFTER THE FLT THE TAPES WERE CHKED AND ALTHOUGH ZTL ISSUED A CLRNC TO 11000 FT WE READ BACK 10000 FT, 250 KTS, AND WERE NEVER CORRECTED. WE BOTH POINTED TO THE SET ALT PRIOR TO THE DSCNT AND FOLLOWED ALL OTHER REQUIRED PROCS. THE INITIAL CALL SIGN MIX-UP MAY HAVE CONTRIBUTED TO THE ERROR. CAPT WAS FLYING AND FO WAS ON THE RADIOS.

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.