Confusion at mco when B737 crew misset transponder and tag up with another company aircraft.

Attributes
ACN	494940
Time
Date	200012
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : mco.airport
State Reference	FL
Altitude	msl single value : 1500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : mco.tracon tower : mco.tower
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Flight Phase	climbout : initial
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 220 flight time total : 23700 flight time type : 20000
ASRS Report	494940
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : multi engine pilot : instrument
Events
Anomaly	non adherence : clearance non adherence : published procedure other anomaly other
Independent Detector	atc equipment other atc equipment : arts equip other controllerb
Resolutory Action	controller : issued new clearance none taken : detected after the fact
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

First officer set transponder to last digit of 4 versus correct number of 5. On departure, we tagged up as another company flight which blocked out at same time and had same initial route. Tower controller cleared us as correct call sign for takeoff. On departure, local used different call to direct us to contact departure. Challenge caused same result. Departure controller quickly sorted out problem and advised us of cause.

Original NASA ASRS Text

Title: CONFUSION AT MCO WHEN B737 CREW MISSET XPONDER AND TAG UP WITH ANOTHER COMPANY ACFT.

Narrative: FO SET XPONDER TO LAST DIGIT OF 4 VERSUS CORRECT NUMBER OF 5. ON DEP, WE TAGGED UP AS ANOTHER COMPANY FLT WHICH BLOCKED OUT AT SAME TIME AND HAD SAME INITIAL RTE. TWR CTLR CLRED US AS CORRECT CALL SIGN FOR TKOF. ON DEP, LCL USED DIFFERENT CALL TO DIRECT US TO CONTACT DEP. CHALLENGE CAUSED SAME RESULT. DEP CTLR QUICKLY SORTED OUT PROB AND ADVISED US OF CAUSE.

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.