Altitude deviation. Excursion from assigned.

Attributes
ACN	114489
Time
Date	198906
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : hou
State Reference	TX
Altitude	msl bound lower : 900 msl bound upper : 2000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : iah
Operator	general aviation : personal
Make Model Name	Small Transport, Low Wing, 2 Recip Eng
Flight Phase	cruise other cruise other descent : approach
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : commercial pilot : instrument
Experience	flight time last 90 days : 35 flight time total : 1802
ASRS Report	114489
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance other spatial deviation
Independent Detector	other controllera
Resolutory Action	flight crew : became reoriented none taken : anomaly accepted other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Last cleared by approach control 'turn left 340 degree to join 30L localizer, maintain 2000' until established on localizer'. The aircraft was descending through 3000' at the time. I performed the pre-landing checklist, lowering flaps 15 degree and landing gear. The left engine was sounding rough. High boost was selected which aggravated the problem and resulted in a partial power loss. The aircraft was allowed to descend through 2000' to 900'. The controller asked 'do you have the airport in sight?' answer, 'yes'. Controller said 'what is your heading?' answer, '340 degree'. Controller asked 'what is your altitude?' answer, '900 ft.' a discussion from the controller ensued saying 'an immediate altitude correction is necessary'. I replied 'I will cancel now' and continued the approach VFR to a normal landing. The situation of the engine distrs during pre-landing checks resulted in a cockpit distraction of at least 1 min. The aircraft's airspeed was adequate to make the field and a landing, single engine if necessary. However, altitude was lost below the assigned altitude of 2000', possibly encroaching on the airspace of another airport (ellington field). Prevention of a recurrence will be up to the pilot to maintain altitude or clearance limits while involved with cockpit operations.

Original NASA ASRS Text

Title: ALT DEVIATION. EXCURSION FROM ASSIGNED.

Narrative: LAST CLRED BY APCH CTL 'TURN LEFT 340 DEG TO JOIN 30L LOC, MAINTAIN 2000' UNTIL ESTABLISHED ON LOC'. THE ACFT WAS DSNDING THROUGH 3000' AT THE TIME. I PERFORMED THE PRE-LNDG CHECKLIST, LOWERING FLAPS 15 DEG AND LNDG GEAR. THE LEFT ENGINE WAS SOUNDING ROUGH. HIGH BOOST WAS SELECTED WHICH AGGRAVATED THE PROBLEM AND RESULTED IN A PARTIAL POWER LOSS. THE ACFT WAS ALLOWED TO DSND THROUGH 2000' TO 900'. THE CTLR ASKED 'DO YOU HAVE THE ARPT IN SIGHT?' ANSWER, 'YES'. CTLR SAID 'WHAT IS YOUR HDG?' ANSWER, '340 DEG'. CTLR ASKED 'WHAT IS YOUR ALT?' ANSWER, '900 FT.' A DISCUSSION FROM THE CTLR ENSUED SAYING 'AN IMMEDIATE ALT CORRECTION IS NECESSARY'. I REPLIED 'I WILL CANCEL NOW' AND CONTINUED THE APCH VFR TO A NORMAL LNDG. THE SITUATION OF THE ENGINE DISTRS DURING PRE-LNDG CHECKS RESULTED IN A COCKPIT DISTR OF AT LEAST 1 MIN. THE ACFT'S AIRSPEED WAS ADEQUATE TO MAKE THE FIELD AND A LNDG, SINGLE ENGINE IF NECESSARY. HOWEVER, ALT WAS LOST BELOW THE ASSIGNED ALT OF 2000', POSSIBLY ENCROACHING ON THE AIRSPACE OF ANOTHER ARPT (ELLINGTON FIELD). PREVENTION OF A RECURRENCE WILL BE UP TO THE PLT TO MAINTAIN ALT OR CLRNC LIMITS WHILE INVOLVED WITH COCKPIT OPERATIONS.

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.