On 7 mi final at iad, B777-200 flight crew experienced a windshear, 60 KT airspeed gain, resulting i...

Attributes
ACN	600402
Time
Date	200311
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : iad.airport
State Reference	VA
Altitude	msl single value : 2800
Environment
Weather Elements	Windshear
Light	Dusk
Aircraft 1
Controlling Facilities	tracon : pct.tracon tower : iad.tower
Operator	common carrier : air carrier
Make Model Name	B777-200
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer & glide slope : 1l
Flight Phase	descent : intermediate altitude descent : approach landing : go around
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 240 flight time total : 6800 flight time type : 1750
ASRS Report	600402
Person 2
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 80 flight time total : 7000 flight time type : 250
ASRS Report	600403
Events
Anomaly	inflight encounter : weather maintenance problem : improper documentation
Independent Detector	other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : executed go around flight crew : exited adverse environment
Supplementary
Problem Areas	ATC Human Performance Weather
Primary Problem	Weather

Narrative:

On final just after GS intercept at 2800 ft MSL, encountered 60 KT change (gain) in airspeed. We were at 180 KTS with flaps 5 degrees. The airspeed went to 250 KTS and the aircraft climbed to 3200 ft MSL in the span of 5 seconds. The winds at altitude were 150 degrees at 38 KTS, while tower was calling 320 degrees at 28 KTS gusting to 38 KTS. After the speed was returned to normal, the aircraft was inside of skins and too high to land. A go around was performed and a second approach and landing were made without further incident. Approximately 10 seconds before the flap overspd, approach informed us that an aircraft was doing a go around due to turbulence, but no mention was made of windshear or airspeed gain or loss. Supplemental information from acn 600403: we experienced a severe windshear with an increase of 60 KTS of airspeed to 250 KIAS for 5 seconds. This was an overspd of the flaps by 30 KTS. The winds had died down by the time of the second approach.

Original NASA ASRS Text

Title: ON 7 MI FINAL AT IAD, B777-200 FLT CREW EXPERIENCED A WINDSHEAR, 60 KT AIRSPD GAIN, RESULTING IN A GAR.

Narrative: ON FINAL JUST AFTER GS INTERCEPT AT 2800 FT MSL, ENCOUNTERED 60 KT CHANGE (GAIN) IN AIRSPD. WE WERE AT 180 KTS WITH FLAPS 5 DEGS. THE AIRSPD WENT TO 250 KTS AND THE ACFT CLBED TO 3200 FT MSL IN THE SPAN OF 5 SECONDS. THE WINDS AT ALT WERE 150 DEGS AT 38 KTS, WHILE TWR WAS CALLING 320 DEGS AT 28 KTS GUSTING TO 38 KTS. AFTER THE SPD WAS RETURNED TO NORMAL, THE ACFT WAS INSIDE OF SKINS AND TOO HIGH TO LAND. A GAR WAS PERFORMED AND A SECOND APCH AND LNDG WERE MADE WITHOUT FURTHER INCIDENT. APPROX 10 SECONDS BEFORE THE FLAP OVERSPD, APCH INFORMED US THAT AN ACFT WAS DOING A GAR DUE TO TURB, BUT NO MENTION WAS MADE OF WINDSHEAR OR AIRSPD GAIN OR LOSS. SUPPLEMENTAL INFO FROM ACN 600403: WE EXPERIENCED A SEVERE WINDSHEAR WITH AN INCREASE OF 60 KTS OF AIRSPD TO 250 KIAS FOR 5 SECONDS. THIS WAS AN OVERSPD OF THE FLAPS BY 30 KTS. THE WINDS HAD DIED DOWN BY THE TIME OF THE SECOND 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.

On 7 mi final at iad, B777-200 flight crew experienced a windshear, 60 KT airspeed gain, resulting in a go around.