Momentary loss of aircraft control.

Attributes
ACN	131966
Time
Date	198912
Day	Sat
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : jfk
State Reference	NY
Altitude	msl bound lower : 2700 msl bound upper : 3000
Environment
Flight Conditions	Mixed
Light	Night
Aircraft 1
Controlling Facilities	tracon : n90
Operator	common carrier : air carrier
Make Model Name	Small Transport, Low Wing, 2 Turboprop Eng
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 : 200 flight time total : 5000 flight time type : 1500
ASRS Report	131966
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	inflight encounter other other anomaly other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : regained aircraft control none taken : unable
Consequence	Other
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	other

Narrative:

Sequence of event during approach for ILS 04R jfk: 1) +/-20 DME, altitude 3000', we were cleared to intercept the localizer 04R, jfk. 2) once established, we are cleared for the approach, ILS 04R, jfk. We then initiated a slow descent at 15.5 DME (narro) to intercept the G/south as published, when suddenly at +/-2700' the left wind dropped violently (+/-30 degrees). I immediately corrected with opp ailerons, then a brisk moment later, dropped again. This time passed the 70-80 degree position to the left. I pulled the aircraft up to the nearest horizon (on instruments) and initiated a climb to 3000'. (The rate of roll was similar to the one of a jet fighter.) I ordered the copilot to explain this was to ATC while I was trying to pacify 8 screaming passenger (no injuries) and approach control vectored us out in a right-hand pattern for a second attempt. Another aircraft was heard behind to report severe turbulence in the same area (+/-20 DME). ATC told us that a heavy jumbo was 5 1/2 mi ahead of us during out approach. How do we avoid this scary experience in the future? Should there be more sep between commuters and heavy jets?

Original NASA ASRS Text

Title: MOMENTARY LOSS OF ACFT CTL.

Narrative: SEQUENCE OF EVENT DURING APCH FOR ILS 04R JFK: 1) +/-20 DME, ALT 3000', WE WERE CLRED TO INTERCEPT THE LOC 04R, JFK. 2) ONCE ESTABLISHED, WE ARE CLRED FOR THE APCH, ILS 04R, JFK. WE THEN INITIATED A SLOW DSCNT AT 15.5 DME (NARRO) TO INTERCEPT THE G/S AS PUBLISHED, WHEN SUDDENLY AT +/-2700' THE LEFT WIND DROPPED VIOLENTLY (+/-30 DEGS). I IMMEDIATELY CORRECTED WITH OPP AILERONS, THEN A BRISK MOMENT LATER, DROPPED AGAIN. THIS TIME PASSED THE 70-80 DEG POS TO THE LEFT. I PULLED THE ACFT UP TO THE NEAREST HORIZON (ON INSTRUMENTS) AND INITIATED A CLB TO 3000'. (THE RATE OF ROLL WAS SIMILAR TO THE ONE OF A JET FIGHTER.) I ORDERED THE COPLT TO EXPLAIN THIS WAS TO ATC WHILE I WAS TRYING TO PACIFY 8 SCREAMING PAX (NO INJURIES) AND APCH CTL VECTORED US OUT IN A RIGHT-HAND PATTERN FOR A SECOND ATTEMPT. ANOTHER ACFT WAS HEARD BEHIND TO RPT SEVERE TURB IN THE SAME AREA (+/-20 DME). ATC TOLD US THAT A HVY JUMBO WAS 5 1/2 MI AHEAD OF US DURING OUT APCH. HOW DO WE AVOID THIS SCARY EXPERIENCE IN THE FUTURE? SHOULD THERE BE MORE SEP BTWN COMMUTERS AND HVY JETS?

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.