GA small aircraft altitude deviation started descent from cruise altitude without clearance.

Attributes
ACN	115557
Time
Date	198906
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : abq airport : 4ac
State Reference	NM
Altitude	msl bound lower : 11500 msl bound upper : 12000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : personal
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Fixed Gear
Flight Phase	cruise other
Route In Use	enroute airway : v187
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : private
Experience	flight time last 90 days : 18 flight time total : 700 flight time type : 400
ASRS Report	115557
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued new clearance other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On final phase of cruise climb on an IFR flight to salt lake city, cleared to 12K, detected oil on windshield. No immediate visibility problems. Prior to takeoff during fuel-up, had suspicion oil cap was not replaced properly. Oil accumulation on windshield, no drop in oil pressure, no increase in cylinder temperature. Corrective action: on detecting problem advised ATC (ZAB) we needed to return to coronado a/P (4AC). Was asked if we had problem and indicated we had under control. Started to set up for slow descent at 15' mp, but did not request descent from assigned altitude. After descent set up ATC requested why I was descending without clearance. Advised we had oil leak and needed slow descent but declined to declare an emergency. We were then advised to descend VFR at pilot's discretion to coronado a/P. Perceptions, judgements, decisions: after advising of need to return to departure a/P, I did not think to request to go back down after just completing climb (I was thinking of the oil leak and how to minimize problem with reduced RPM's/mp, return and land). Actions taken: upon return found oil cap off, added 2 qts of oil, cleaned engine and resumed flight uneventful.

Original NASA ASRS Text

Title: GA SMA ALT DEVIATION STARTED DESCENT FROM CRUISE ALT WITHOUT CLRNC.

Narrative: ON FINAL PHASE OF CRUISE CLIMB ON AN IFR FLT TO SALT LAKE CITY, CLRED TO 12K, DETECTED OIL ON WINDSHIELD. NO IMMEDIATE VISIBILITY PROBLEMS. PRIOR TO TKOF DURING FUEL-UP, HAD SUSPICION OIL CAP WAS NOT REPLACED PROPERLY. OIL ACCUMULATION ON WINDSHIELD, NO DROP IN OIL PRESSURE, NO INCREASE IN CYLINDER TEMPERATURE. CORRECTIVE ACTION: ON DETECTING PROBLEM ADVISED ATC (ZAB) WE NEEDED TO RETURN TO CORONADO A/P (4AC). WAS ASKED IF WE HAD PROBLEM AND INDICATED WE HAD UNDER CONTROL. STARTED TO SET UP FOR SLOW DSCNT AT 15' MP, BUT DID NOT REQUEST DSCNT FROM ASSIGNED ALT. AFTER DSCNT SET UP ATC REQUESTED WHY I WAS DESCENDING WITHOUT CLRNC. ADVISED WE HAD OIL LEAK AND NEEDED SLOW DSCNT BUT DECLINED TO DECLARE AN EMER. WE WERE THEN ADVISED TO DSND VFR AT PLT'S DISCRETION TO CORONADO A/P. PERCEPTIONS, JUDGEMENTS, DECISIONS: AFTER ADVISING OF NEED TO RETURN TO DEP A/P, I DID NOT THINK TO REQUEST TO GO BACK DOWN AFTER JUST COMPLETING CLIMB (I WAS THINKING OF THE OIL LEAK AND HOW TO MINIMIZE PROBLEM WITH REDUCED RPM'S/MP, RETURN AND LAND). ACTIONS TAKEN: UPON RETURN FOUND OIL CAP OFF, ADDED 2 QTS OF OIL, CLEANED ENGINE AND RESUMED FLT UNEVENTFUL.

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.