Aircraft flew into ADIZ squawking wrong transponder code.

Attributes
ACN	274022
Time
Date	199406
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : eyw
State Reference	FL
Altitude	msl bound lower : 5500 msl bound upper : 5500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zma tracon : nqx
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 135
Flight Phase	cruise other
Flight Plan	VFR
Aircraft 2
Operator	other
Make Model Name	Fighter
Operating Under FAR Part	other : other
Flight Phase	cruise other
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 7000 flight time type : 180
ASRS Report	274022
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : less severe non adherence : published procedure non adherence : far
Independent Detector	other controllera other flight crewa
Resolutory Action	none taken : insufficient time
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

Transponder was emitting an incorrect squawk code than what was indicated on box. Aircraft flight departed with a xx squawk given from miami FSS to fort jefferson. Upon returning and crossing the ADIZ, xx was still squawking, but apparently was emitting xy. 2 fighters were dispatched and intercepted us. When we came within 12 mi of coast we contacted eyw tower and they asked why we were squawking xy when in fact we were squawking xx. The item was written up upon arrival and repaired with a waiver to return to fll maintenance base. This problem was difficult to pin down since the transponder did work properly on certain codes, however, in future I will call key west navy approach for verification of code.

Original NASA ASRS Text

Title: ACFT FLEW INTO ADIZ SQUAWKING WRONG XPONDER CODE.

Narrative: XPONDER WAS EMITTING AN INCORRECT SQUAWK CODE THAN WHAT WAS INDICATED ON BOX. ACFT FLT DEPARTED WITH A XX SQUAWK GIVEN FROM MIAMI FSS TO FORT JEFFERSON. UPON RETURNING AND XING THE ADIZ, XX WAS STILL SQUAWKING, BUT APPARENTLY WAS EMITTING XY. 2 FIGHTERS WERE DISPATCHED AND INTERCEPTED US. WHEN WE CAME WITHIN 12 MI OF COAST WE CONTACTED EYW TWR AND THEY ASKED WHY WE WERE SQUAWKING XY WHEN IN FACT WE WERE SQUAWKING XX. THE ITEM WAS WRITTEN UP UPON ARR AND REPAIRED WITH A WAIVER TO RETURN TO FLL MAINT BASE. THIS PROB WAS DIFFICULT TO PIN DOWN SINCE THE XPONDER DID WORK PROPERLY ON CERTAIN CODES, HOWEVER, IN FUTURE I WILL CALL KEY WEST NAVY APCH FOR VERIFICATION OF CODE.

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.