<< >> NASA ASRS Report 753795, September 2007

A B737-800 crew reports a possible wake vortex encounter at FL370 and 240 KTS. A 300 ft climb was followed by a 500 ft descent.

Attributes
ACN	753795
Time
Date	200709
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : zfw.artcc
State Reference	TX
Altitude	msl single value : 37000
Environment
Flight Conditions	VMC
Aircraft 1
Controlling Facilities	artcc : zfw.artcc
Operator	common carrier : air carrier
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 210 flight time total : 11000 flight time type : 800
ASRS Report	753795
Events
Anomaly	inflight encounter : wake turbulence other anomaly
Independent Detector	other flight crewa
Resolutory Action	flight crew : regained aircraft control
Supplementary
Problem Areas	Aircraft Environmental Factor
Primary Problem	Environmental Factor

Narrative:

We were departing holding at phils on the glen rose eight into dfw. We were proceeding to a second hold at brownwood on the same arrival at FL370. Our airspeed was ten knots above best hold speed approximately 230 KTS. We encountered what I believe was wake turbulence. The event began with moderate shudder followed immediately by an abrupt 300 ft climb. The autoplt followed with a 500 ft descent before returning to FL370. ZFW called and requested that we remain at FL370. Flight conditions prior to and during the event were clear. The flight had been smooth up until the event. Our flight was completed without further incident.

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Original NASA ASRS Text

Title: A B737-800 CREW RPTS A POSSIBLE WAKE VORTEX ENCOUNTER AT FL370 AND 240 KTS. A 300 FT CLB WAS FOLLOWED BY A 500 FT DSCNT.

Narrative: WE WERE DEPARTING HOLDING AT PHILS ON THE GLEN ROSE EIGHT INTO DFW. WE WERE PROCEEDING TO A SECOND HOLD AT BROWNWOOD ON THE SAME ARR AT FL370. OUR AIRSPD WAS TEN KNOTS ABOVE BEST HOLD SPEED APPROX 230 KTS. WE ENCOUNTERED WHAT I BELIEVE WAS WAKE TURB. THE EVENT BEGAN WITH MODERATE SHUDDER FOLLOWED IMMEDIATELY BY AN ABRUPT 300 FT CLB. THE AUTOPLT FOLLOWED WITH A 500 FT DESCENT BEFORE RETURNING TO FL370. ZFW CALLED AND REQUESTED THAT WE REMAIN AT FL370. FLT CONDITIONS PRIOR TO AND DURING THE EVENT WERE CLEAR. THE FLT HAD BEEN SMOOTH UP UNTIL THE EVENT. OUR FLT WAS COMPLETED WITHOUT FURTHER INCIDENT.

Data retrieved from NASA's ASRS site as of January 2009 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.