An small aircraft pilot squawked the wrong transponder code, spawning a military intercept.

Attributes
ACN	531513
Time
Date	200111
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 1000
Environment
Light	Daylight
Aircraft 1
Operator	common carrier : air taxi
Make Model Name	Helicopter
Operating Under FAR Part	Part 135
Flight Phase	cruise : level
Flight Plan	VFR
Aircraft 2
Operator	other
Make Model Name	Fighter
Flight Phase	cruise : level
Person 1
Affiliation	company : air taxi
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial
Experience	flight time last 90 days : 1000 flight time total : 21000 flight time type : 500
ASRS Report	531513
Person 2
Affiliation	company : air taxi
Function	other personnel other
Events
Anomaly	non adherence : clearance non adherence : published procedure other anomaly other
Independent Detector	other other : intercept afct
Resolutory Action	flight crew : landed as precaution
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Flight Crew Human Performance FAA Airspace Structure
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I had been flying aircraft XXXX. It developed mechanical problems and was replaced by aircraft YYYY. I did not check the transponder code before takeoff. The wrong code was set in the transponder. I was approached by a military aircraft. I landed and set the correct code. My radio operator gave me a phone # to call and explain my actions. I called and spoke to mr X. I explained what had transpired. I asked if there was anything else I had to do and was told no. I received a call from mr Y. He needed to know what went on and I explained everything to him. I asked him if there was anything else I needed to do and he said no. My office, in ZZZ2, called and said I needed to send this copy to mr Z. What caused this problem was inattention to detail. It will not happen again.

Original NASA ASRS Text

Title: AN SMA PLT SQUAWKED THE WRONG XPONDER CODE, SPAWNING A MIL INTERCEPT.

Narrative: I HAD BEEN FLYING ACFT XXXX. IT DEVELOPED MECHANICAL PROBS AND WAS REPLACED BY ACFT YYYY. I DID NOT CHECK THE XPONDER CODE BEFORE TAKEOFF. THE WRONG CODE WAS SET IN THE XPONDER. I WAS APCHED BY A MIL ACFT. I LANDED AND SET THE CORRECT CODE. MY RADIO OPERATOR GAVE ME A PHONE # TO CALL AND EXPLAIN MY ACTIONS. I CALLED AND SPOKE TO MR X. I EXPLAINED WHAT HAD TRANSPIRED. I ASKED IF THERE WAS ANYTHING ELSE I HAD TO DO AND WAS TOLD NO. I RECEIVED A CALL FROM MR Y. HE NEEDED TO KNOW WHAT WENT ON AND I EXPLAINED EVERYTHING TO HIM. I ASKED HIM IF THERE WAS ANYTHING ELSE I NEEDED TO DO AND HE SAID NO. MY OFFICE, IN ZZZ2, CALLED AND SAID I NEEDED TO SEND THIS COPY TO MR Z. WHAT CAUSED THIS PROB WAS INATTENTION TO DETAIL. IT WILL NOT HAPPEN AGAIN.

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.