Pilot of an aero commander 500 experienced an altitude deviation while being vectored for approach.

Attributes
ACN	834293
Time
Date	200905
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Make Model Name	Aero Commander 500 Series
Operating Under FAR Part	Part 135
Flight Phase	Descent Initial Approach Final Approach
Route In Use	Vectors
Flight Plan	IFR
Component
Aircraft Component	Positional / Directional Sensing
Person 1
Function	Pilot Not Flying Captain
Qualification	Flight Crew Multiengine Flight Crew Instrument Flight Crew Commercial Flight Crew Flight Instructor
Experience	Flight Crew Last 90 Days 280 Flight Crew Total 2200 Flight Crew Type 900
Events
Anomaly	Deviation - Altitude Overshoot Deviation - Procedural Clearance Deviation - Track / Heading All Types

Narrative:

At approximately 10 NM from the airport; was given an intercept vector of 210 and cleared for the approach with an altitude restriction of 2600 ft MSL until established on the localizer. While rolling through approximately 260 degrees; the controller realized that the aircraft would pass through the localizer and amended the heading to 160 degrees. In the process of turning; the directional gyro precessed approximately 20 degrees. This caused the aircraft to roll out on a 140 degree heading on the magnetic compass. As the aircraft passed through the localizer again; correction was made to re-intercept the localizer. In the process of this maneuvering; the aircraft descended to 2400 ft MSL; 200 ft below the glideslope intercept. At this point the aircraft was in VMC and the runway was in sight. The controller queried as to if the aircraft was established on the localizer. I responded with 'no; but we have the runway in sight.' he then confirmed if we had the runway in sight and I responded in the affirmative. He then handed us off to tower.

Original NASA ASRS Text

Title: Pilot of an Aero Commander 500 experienced an altitude deviation while being vectored for approach.

Narrative: At approximately 10 NM from the airport; was given an intercept vector of 210 and cleared for the approach with an altitude restriction of 2600 FT MSL until established on the localizer. While rolling through approximately 260 degrees; the controller realized that the aircraft would pass through the localizer and amended the heading to 160 degrees. In the process of turning; the directional gyro precessed approximately 20 degrees. This caused the aircraft to roll out on a 140 degree heading on the magnetic compass. As the aircraft passed through the localizer again; correction was made to re-intercept the localizer. In the process of this maneuvering; the aircraft descended to 2400 FT MSL; 200 FT below the glideslope intercept. At this point the aircraft was in VMC and the runway was in sight. The Controller queried as to if the aircraft was established on the localizer. I responded with 'No; but we have the runway in sight.' He then confirmed if we had the runway in sight and I responded in the affirmative. He then handed us off to tower.

Data retrieved from NASA's ASRS site as of April 2012 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.