A B747 landing at jfk, ny, deviates from initial approach altitude due to turbulence in the area.

Attributes
ACN	394240
Time
Date	199802
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : jfk
State Reference	NY
Altitude	msl bound lower : 1800 msl bound upper : 2000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	tower : jfk
Operator	common carrier : air carrier
Make Model Name	B747 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 30 flight time total : 15000
ASRS Report	394240
Person 2
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 0 flight time total : 8000 flight time type : 0
ASRS Report	394390
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter other non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Weather
Air Traffic Incident	Pilot Deviation

Narrative:

During an ILS approach to runway 13L at jfk on feb/xa/98 at approximately PM40, heavy turbulence was encountered. The aircraft was cleared to 2000 ft and cleared for the ILS approach. Heavy downdrafts were encountered which caused the aircraft to descend to approximately 1800 ft before control was re-established and 2000 ft was maintained until GS interception, and a successful ILS landing was completed. Some altimeter discrepancies were noted during the approach.

Original NASA ASRS Text

Title: A B747 LNDG AT JFK, NY, DEVIATES FROM INITIAL APCH ALT DUE TO TURB IN THE AREA.

Narrative: DURING AN ILS APCH TO RWY 13L AT JFK ON FEB/XA/98 AT APPROX PM40, HVY TURB WAS ENCOUNTERED. THE ACFT WAS CLRED TO 2000 FT AND CLRED FOR THE ILS APCH. HVY DOWNDRAFTS WERE ENCOUNTERED WHICH CAUSED THE ACFT TO DSND TO APPROX 1800 FT BEFORE CTL WAS RE-ESTABLISHED AND 2000 FT WAS MAINTAINED UNTIL GS INTERCEPTION, AND A SUCCESSFUL ILS LNDG WAS COMPLETED. SOME ALTIMETER DISCREPANCIES WERE NOTED DURING THE APCH.

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.