Large transport flight crew responds to wrong call sign. 2 aircraft on runway for takeoff.

Attributes
ACN	251057
Time
Date	199309
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : msp
State Reference	MN
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	ground : holding
Flight Plan	IFR
Aircraft 2
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Flight Phase	climbout : takeoff ground : holding
Person 1
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : flight engineer pilot : commercial pilot : atp pilot : instrument
Experience	flight time last 90 days : 215 flight time total : 10300 flight time type : 3600
ASRS Report	251057
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : ground less severe incursion : runway non adherence : clearance other anomaly other
Independent Detector	other flight crewa
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Cleared onto hold, runway 29L at msp. Aircraft moved onto runway and stopped in position, then cleared for immediate takeoff. Clearance acknowledged and roll initiated. Aircraft had begun to move when light twin was observed rolling onto runway at midfield and commencing a rolling takeoff. We stopped and questioned tower about clearance. Suspect we had acknowledged twin's takeoff clearance at the same time he did, cutting each other out. No real conflict, but potential for a real problem was there.

Original NASA ASRS Text

Title: LGT FLC RESPONDS TO WRONG CALL SIGN. 2 ACFT ON RWY FOR TKOF.

Narrative: CLRED ONTO HOLD, RWY 29L AT MSP. ACFT MOVED ONTO RWY AND STOPPED IN POS, THEN CLRED FOR IMMEDIATE TKOF. CLRNC ACKNOWLEDGED AND ROLL INITIATED. ACFT HAD BEGUN TO MOVE WHEN LIGHT TWIN WAS OBSERVED ROLLING ONTO RWY AT MIDFIELD AND COMMENCING A ROLLING TKOF. WE STOPPED AND QUESTIONED TWR ABOUT CLRNC. SUSPECT WE HAD ACKNOWLEDGED TWIN'S TKOF CLRNC AT THE SAME TIME HE DID, CUTTING EACH OTHER OUT. NO REAL CONFLICT, BUT POTENTIAL FOR A REAL PROB WAS THERE.

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.