Non use of transponder mode C when required.

Attributes
ACN	123537
Time
Date	198909
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : dca
State Reference	DC
Altitude	msl bound lower : 1500 msl bound upper : 3500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : dca
Operator	general aviation : personal
Make Model Name	Small Aircraft
Flight Phase	cruise other cruise other
Flight Plan	None
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : flight engineer pilot : cfi pilot : atp pilot : instrument
Experience	flight time last 90 days : 200 flight time total : 10000 flight time type : 65
ASRS Report	123537
Events
Anomaly	inflight encounter : weather non adherence : far
Independent Detector	other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Commenced VFR solo x-country flight from summer base (wwd) to home airport (west 10). Afternoon of 9/tue/89, after passing easton, md, WX deteriorated and impending darkness forced flight to return to easton and ron. Next morning of 9/wed/89, flight departed easton for manassas, va (west 10). WX deteriorated as flight progressed west (as forecast), and in vicinity of clifton, md, aqua land airport course was reversed and flight returned to easton for refueling and then back to cope may (wwd) to await a fairer day (and passing of hugo). As per pilot's custom and background, while not in vicinity of congested airspace or vicinity of arwys and IFR routes, transponder was left in standby. Flight was planned and operated well clear of washington TCA. Subsequent inspection of newly purchased TCA chart disclosed 30 NM arc around dca airport annotated for mode C per far 91.24/aim! Flight operated within 30 NM arc on 9/wed/89, and perhaps on 9/tue/89, with transponder in standby!! Review of far 91.24 was enlightening, but also confusing. 91.24C (my interpretation) makes it sound as if transponder and mode C must be on for all flts 'in controled airspace,' ie, virtually all the time. A call to local FSDO was less than enlightening.

Original NASA ASRS Text

Title: NON USE OF TRANSPONDER MODE C WHEN REQUIRED.

Narrative: COMMENCED VFR SOLO X-COUNTRY FLT FROM SUMMER BASE (WWD) TO HOME ARPT (W 10). AFTERNOON OF 9/TUE/89, AFTER PASSING EASTON, MD, WX DETERIORATED AND IMPENDING DARKNESS FORCED FLT TO RETURN TO EASTON AND RON. NEXT MORNING OF 9/WED/89, FLT DEPARTED EASTON FOR MANASSAS, VA (W 10). WX DETERIORATED AS FLT PROGRESSED W (AS FORECAST), AND IN VICINITY OF CLIFTON, MD, AQUA LAND ARPT COURSE WAS REVERSED AND FLT RETURNED TO EASTON FOR REFUELING AND THEN BACK TO COPE MAY (WWD) TO AWAIT A FAIRER DAY (AND PASSING OF HUGO). AS PER PLT'S CUSTOM AND BACKGROUND, WHILE NOT IN VICINITY OF CONGESTED AIRSPACE OR VICINITY OF ARWYS AND IFR ROUTES, XPONDER WAS LEFT IN STANDBY. FLT WAS PLANNED AND OPERATED WELL CLR OF WASHINGTON TCA. SUBSEQUENT INSPECTION OF NEWLY PURCHASED TCA CHART DISCLOSED 30 NM ARC AROUND DCA ARPT ANNOTATED FOR MODE C PER FAR 91.24/AIM! FLT OPERATED WITHIN 30 NM ARC ON 9/WED/89, AND PERHAPS ON 9/TUE/89, WITH XPONDER IN STANDBY!! REVIEW OF FAR 91.24 WAS ENLIGHTENING, BUT ALSO CONFUSING. 91.24C (MY INTERP) MAKES IT SOUND AS IF XPONDER AND MODE C MUST BE ON FOR ALL FLTS 'IN CTLED AIRSPACE,' IE, VIRTUALLY ALL THE TIME. A CALL TO LCL FSDO WAS LESS THAN ENLIGHTENING.

Data retrieved from NASA's ASRS site as of August 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.