DC9 crew and ZMP controllers were confused by aircraft with similar call sign.

Attributes
ACN	491929
Time
Date	200011
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : eau.vortac
State Reference	WI
Altitude	msl bound lower : 11000 msl bound upper : 35000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zmp.artcc
Operator	common carrier : air carrier
Make Model Name	DC-9 Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	descent : vacating altitude
Route In Use	arrival star : eau clare 4
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zmp.artcc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude descent : vacating altitude
Route In Use	arrival star : eauclare 4
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 110 flight time total : 11000 flight time type : 7000
ASRS Report	491929
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : commercial pilot : instrument
Events
Anomaly	other anomaly other
Independent Detector	other controllera other controllerb other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance none taken : anomaly accepted
Supplementary
Problem Areas	FAA Flight Crew Human Performance Company ATC Human Performance
Primary Problem	Company
Air Traffic Incident	Pilot Deviation

Narrative:

Given clearance from 35000 ft to 24000 ft, pilot's discretion. Several other flts with similar call signs and a controller receiving training, by voice coming through telling him things to say. Our flight was #abcd, a ferry flight. We kept hearing a call to abce, bce, etc. Abce was giving clearance to cross twinz on eau clare four arrival at 11000 ft. We were pilot's discretion to 24000 ft. At eau VOR we were questioned on our altitude. Reply was 28000 ft and descending. At 27500 ft, 15 seconds later, asked again our altitude. Then given a turn north, east, south, then west to rejoin with descent clearance to 14000 ft, then finally 11000 ft at twinz. Several aircraft were using similar call signs, not only ours, but other airlines. We got caught up in the confusion without a clearance for our call sign. The controller never questioned us but just gave us vectors to get down. He had his hands full at this time, and either we missed his descent clearance by the call sign confusion or it was never issued to our call sign. At least we never heard one. Certain times of the day are worse than others, but I would think we could come up with a numbering system that would take away from the chances of this happening. Similar call signs are always going to be out there, but they should not be at the same airline.

Original NASA ASRS Text

Title: DC9 CREW AND ZMP CTLRS WERE CONFUSED BY ACFT WITH SIMILAR CALL SIGN.

Narrative: GIVEN CLRNC FROM 35000 FT TO 24000 FT, PLT'S DISCRETION. SEVERAL OTHER FLTS WITH SIMILAR CALL SIGNS AND A CTLR RECEIVING TRAINING, BY VOICE COMING THROUGH TELLING HIM THINGS TO SAY. OUR FLT WAS #ABCD, A FERRY FLT. WE KEPT HEARING A CALL TO ABCE, BCE, ETC. ABCE WAS GIVING CLRNC TO CROSS TWINZ ON EAU CLARE FOUR ARR AT 11000 FT. WE WERE PLT'S DISCRETION TO 24000 FT. AT EAU VOR WE WERE QUESTIONED ON OUR ALT. REPLY WAS 28000 FT AND DSNDING. AT 27500 FT, 15 SECONDS LATER, ASKED AGAIN OUR ALT. THEN GIVEN A TURN N, E, S, THEN W TO REJOIN WITH DSCNT CLRNC TO 14000 FT, THEN FINALLY 11000 FT AT TWINZ. SEVERAL ACFT WERE USING SIMILAR CALL SIGNS, NOT ONLY OURS, BUT OTHER AIRLINES. WE GOT CAUGHT UP IN THE CONFUSION WITHOUT A CLRNC FOR OUR CALL SIGN. THE CTLR NEVER QUESTIONED US BUT JUST GAVE US VECTORS TO GET DOWN. HE HAD HIS HANDS FULL AT THIS TIME, AND EITHER WE MISSED HIS DSCNT CLRNC BY THE CALL SIGN CONFUSION OR IT WAS NEVER ISSUED TO OUR CALL SIGN. AT LEAST WE NEVER HEARD ONE. CERTAIN TIMES OF THE DAY ARE WORSE THAN OTHERS, BUT I WOULD THINK WE COULD COME UP WITH A NUMBERING SYS THAT WOULD TAKE AWAY FROM THE CHANCES OF THIS HAPPENING. SIMILAR CALL SIGNS ARE ALWAYS GOING TO BE OUT THERE, BUT THEY SHOULD NOT BE AT THE SAME AIRLINE.

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.