Track deviation develops when C172 pilot fails to correct gyro compass precession.

Attributes
ACN	736582
Time
Date	200704
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : adw.airport
State Reference	MD
Altitude	msl single value : 3000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : pct.tracon
Operator	other
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : military
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : multi engine pilot : private pilot : atp pilot : commercial
Experience	flight time last 90 days : 25 flight time total : 6000 flight time type : 180
ASRS Report	736582
Person 2
Affiliation	government : faa
Function	controller : approach
Events
Anomaly	aircraft equipment problem : critical non adherence : clearance non adherence : published procedure other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued advisory flight crew : returned to intended or assigned course flight crew : overcame equipment problem flight crew : became reoriented
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Flight Crew Human Performance

Narrative:

Given clearance to takeoff on runway 1R at adw; climb 3000 ft; right turn 180 degrees. Tower passed me off to potomac approach. After approximately 5 mins with potomac; the controller queried me on my heading. I replied that I was maintaining 180 degrees. He informed me that my actual heading was 240 degrees. I then checked my gyro compass with my whiskey compass; and confirmed that my gyro was 60 degrees off. I have been flying mostly aircraft with synchronized gyros. With this aircraft; the gyro had precessed 60 degrees; and I had never crosschecked the heading prior to takeoff. Regardless of system; I need to develop habit of checking aircraft heading when lined up for takeoff.

Original NASA ASRS Text

Title: TRACK DEVIATION DEVELOPS WHEN C172 PLT FAILS TO CORRECT GYRO COMPASS PRECESSION.

Narrative: GIVEN CLRNC TO TKOF ON RWY 1R AT ADW; CLB 3000 FT; R TURN 180 DEGS. TWR PASSED ME OFF TO POTOMAC APCH. AFTER APPROX 5 MINS WITH POTOMAC; THE CTLR QUERIED ME ON MY HDG. I REPLIED THAT I WAS MAINTAINING 180 DEGS. HE INFORMED ME THAT MY ACTUAL HDG WAS 240 DEGS. I THEN CHKED MY GYRO COMPASS WITH MY WHISKEY COMPASS; AND CONFIRMED THAT MY GYRO WAS 60 DEGS OFF. I HAVE BEEN FLYING MOSTLY ACFT WITH SYNCHRONIZED GYROS. WITH THIS ACFT; THE GYRO HAD PRECESSED 60 DEGS; AND I HAD NEVER XCHKED THE HDG PRIOR TO TKOF. REGARDLESS OF SYS; I NEED TO DEVELOP HABIT OF CHKING ACFT HDG WHEN LINED UP FOR TKOF.

Data retrieved from NASA's ASRS site as of January 2009 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.