An air carrier flight crew deviates from assigned altitude while in approach into isp.

Attributes
ACN	517800
Time
Date	200107
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	navaid : ccc.vor
State Reference	NY
Altitude	msl bound lower : 1650 msl bound upper : 2000
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Controlling Facilities	tower : zzz.tower
Operator	common carrier : air taxi
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air taxi
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 1200 flight time total : 3700 flight time type : 2500
ASRS Report	517800
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Resolutory Action	controller : issued advisory flight crew : returned to assigned altitude
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

First officer (copilot) flying ILS 24 approach to long island's islip airport (isp). While attempting to gain visual contact of the airport, the first officer failed to maintain last assigned altitude, 2000 ft MSL. Approach controller gave a verbal altitude alert, and crew realized the aircraft was approximately 300-350 ft below assigned altitude. Corrective action was taken immediately and approach control handed the aircraft over to tower. Approach and landing completed without incident.

Original NASA ASRS Text

Title: AN ACR FLT CREW DEVIATES FROM ASSIGNED ALT WHILE IN APCH INTO ISP.

Narrative: FO (COPLT) FLYING ILS 24 APCH TO LONG ISLAND'S ISLIP ARPT (ISP). WHILE ATTEMPTING TO GAIN VISUAL CONTACT OF THE ARPT, THE FO FAILED TO MAINTAIN LAST ASSIGNED ALT, 2000 FT MSL. APCH CTLR GAVE A VERBAL ALT ALERT, AND CREW REALIZED THE ACFT WAS APPROX 300-350 FT BELOW ASSIGNED ALT. CORRECTIVE ACTION WAS TAKEN IMMEDIATELY AND APCH CTL HANDED THE ACFT OVER TO TWR. APCH AND LNDG COMPLETED WITHOUT INCIDENT.

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