Pilot of C172 inadvertently pushes 'VFR' button on transponder while in dc ADIZ.

Attributes
ACN	612879
Time
Date	200403
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : jyo.airport
State Reference	VA
Altitude	msl single value : 2000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : pct.tracon
Operator	general aviation : personal
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	descent : intermediate altitude
Flight Plan	VFR
Aircraft 2
Controlling Facilities	tower : jyo.tower
Operator	general aviation : personal
Make Model Name	PA-24 Comanche
Route In Use	approach : traffic pattern
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : commercial pilot : cfi pilot : multi engine
Experience	flight time last 90 days : 60 flight time total : 840 flight time type : 720
ASRS Report	612879
Person 2
Function	flight crew : single pilot
Events
Anomaly	airspace violation : entry non adherence : clearance non adherence : far non adherence : published procedure
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Flight Crew Human Performance Airspace Structure Environmental Factor
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation
Situations
Airspace Structure	special use : dcadiz.othersua

Narrative:

I reported jyo in sight to potomac approach. They said 'aircraft calling potomac, radar service terminated, frequency change approved, remain on the beacon code until on the ground, maintain VFR.' as I was reading back what he said, I must have pressed the 'VFR' button on the transponder, which automatically squawks 1200. I had not realized this until I had completed my after landing checklist, when I turned the transponder to 'standby.' I had been told to contact potomac by a comanche in the traffic pattern and it was when I completed my after landing checklist when I realized what I did wrong. I have been flying almost every day in the ADIZ and I am very familiar with the procedures. In order to prevent this from recurring again would be to develop a mental or written checklist at the time of frequency change and radar service termination to include squawking 'altitude' with correct 'squawk code' in order to verify that the 'VFR' button was not pressed.

Original NASA ASRS Text

Title: PLT OF C172 INADVERTENTLY PUSHES 'VFR' BUTTON ON XPONDER WHILE IN DC ADIZ.

Narrative: I RPTED JYO IN SIGHT TO POTOMAC APCH. THEY SAID 'ACFT CALLING POTOMAC, RADAR SVC TERMINATED, FREQ CHANGE APPROVED, REMAIN ON THE BEACON CODE UNTIL ON THE GND, MAINTAIN VFR.' AS I WAS READING BACK WHAT HE SAID, I MUST HAVE PRESSED THE 'VFR' BUTTON ON THE XPONDER, WHICH AUTOMATICALLY SQUAWKS 1200. I HAD NOT REALIZED THIS UNTIL I HAD COMPLETED MY AFTER LNDG CHKLIST, WHEN I TURNED THE XPONDER TO 'STANDBY.' I HAD BEEN TOLD TO CONTACT POTOMAC BY A COMANCHE IN THE TFC PATTERN AND IT WAS WHEN I COMPLETED MY AFTER LNDG CHKLIST WHEN I REALIZED WHAT I DID WRONG. I HAVE BEEN FLYING ALMOST EVERY DAY IN THE ADIZ AND I AM VERY FAMILIAR WITH THE PROCS. IN ORDER TO PREVENT THIS FROM RECURRING AGAIN WOULD BE TO DEVELOP A MENTAL OR WRITTEN CHKLIST AT THE TIME OF FREQ CHANGE AND RADAR SVC TERMINATION TO INCLUDE SQUAWKING 'ALT' WITH CORRECT 'SQUAWK CODE' IN ORDER TO VERIFY THAT THE 'VFR' BUTTON WAS NOT PRESSED.

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.