Wake encounter -- a commuter aircraft hits the wake of a B767-200 and recovers, but changes runways ...

Attributes
ACN	309589
Time
Date	199507
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : pit
State Reference	PA
Altitude	msl bound lower : 5000 msl bound upper : 5000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : pit
Operator	common carrier : air carrier
Make Model Name	Jetstream 31
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	B767-200
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : commercial pilot : cfi pilot : atp pilot : instrument
Experience	flight time last 90 days : 170 flight time total : 4500 flight time type : 1500
ASRS Report	309589
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	inflight encounter other other anomaly other
Independent Detector	other flight crewa
Resolutory Action	controller : issued new clearance other other
Consequence	faa : reviewed incident with flight crew
Supplementary
Air Traffic Incident	other

Narrative:

We were approaching the pittsburg area and advised that we were following a B767 5 mi ahead. The captain and I spotted the traffic ahead of us. At the time we were at 6000 ft and were questioning whether we were actually 5 mi behind the B767. Approach control then instructed us to slow to 180 KTS and descend to 4000 ft. I was hesitant to start a descent to an altitude below the B767. I started a descent, but the captain and I decided to level off at 5000 ft and start down again once I was a DOT above the GS. Unfortunately, I descended below the B767 and at about 10 mi out, we rolled to the left about 20-30 degrees. We landed without further incident on runway 28L. After reviewing the situation, I should not have accepted the descent clearance to 4000 ft. We did not have TCASII on board to confirm the 5 mi distance. Callback conversation with reporter revealed the following information: the reporter was flying a bae jetstream 31 and the preceding aircraft was a B767-200. The flight crew of the jetstream could see the preceding aircraft, but they could not tell its type because of a bright sunlight reflection from it in the morning sun. When the controller started the reporter down to 4000 ft the flight crew asked about the preceding type and then they decided to slow their descent rate in an attempt to stay above any possible wake. They were at 5000 ft by now and they hit the wake as they were discussing that possibility. The aircraft was only partially controllable and the first officer (flying) applied a large amount of right rudder and the captain added some right aileron and the aircraft, after some hesitation, slowly rolled wings level. The reporter said that the captain decided after the encounter to not follow the B767-200 and ordered a go around. As he advanced the power the captain informed the controller of his decision and the controller offered runway 28R to them and they accepted performing a visual approach.

Original NASA ASRS Text

Title: WAKE ENCOUNTER -- A COMMUTER ACFT HITS THE WAKE OF A B767-200 AND RECOVERS, BUT CHANGES RWYS TO AVOID ANY FURTHER ENCOUNTERS.

Narrative: WE WERE APCHING THE PITTSBURG AREA AND ADVISED THAT WE WERE FOLLOWING A B767 5 MI AHEAD. THE CAPT AND I SPOTTED THE TFC AHEAD OF US. AT THE TIME WE WERE AT 6000 FT AND WERE QUESTIONING WHETHER WE WERE ACTUALLY 5 MI BEHIND THE B767. APCH CTL THEN INSTRUCTED US TO SLOW TO 180 KTS AND DSND TO 4000 FT. I WAS HESITANT TO START A DSCNT TO AN ALT BELOW THE B767. I STARTED A DSCNT, BUT THE CAPT AND I DECIDED TO LEVEL OFF AT 5000 FT AND START DOWN AGAIN ONCE I WAS A DOT ABOVE THE GS. UNFORTUNATELY, I DSNDED BELOW THE B767 AND AT ABOUT 10 MI OUT, WE ROLLED TO THE L ABOUT 20-30 DEGS. WE LANDED WITHOUT FURTHER INCIDENT ON RWY 28L. AFTER REVIEWING THE SIT, I SHOULD NOT HAVE ACCEPTED THE DSCNT CLRNC TO 4000 FT. WE DID NOT HAVE TCASII ON BOARD TO CONFIRM THE 5 MI DISTANCE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR WAS FLYING A BAE JETSTREAM 31 AND THE PRECEDING ACFT WAS A B767-200. THE FLC OF THE JETSTREAM COULD SEE THE PRECEDING ACFT, BUT THEY COULD NOT TELL ITS TYPE BECAUSE OF A BRIGHT SUNLIGHT REFLECTION FROM IT IN THE MORNING SUN. WHEN THE CTLR STARTED THE RPTR DOWN TO 4000 FT THE FLC ASKED ABOUT THE PRECEDING TYPE AND THEN THEY DECIDED TO SLOW THEIR DSCNT RATE IN AN ATTEMPT TO STAY ABOVE ANY POSSIBLE WAKE. THEY WERE AT 5000 FT BY NOW AND THEY HIT THE WAKE AS THEY WERE DISCUSSING THAT POSSIBILITY. THE ACFT WAS ONLY PARTIALLY CONTROLLABLE AND THE FO (FLYING) APPLIED A LARGE AMOUNT OF R RUDDER AND THE CAPT ADDED SOME R AILERON AND THE ACFT, AFTER SOME HESITATION, SLOWLY ROLLED WINGS LEVEL. THE RPTR SAID THAT THE CAPT DECIDED AFTER THE ENCOUNTER TO NOT FOLLOW THE B767-200 AND ORDERED A GAR. AS HE ADVANCED THE PWR THE CAPT INFORMED THE CTLR OF HIS DECISION AND THE CTLR OFFERED RWY 28R TO THEM AND THEY ACCEPTED PERFORMING A VISUAL 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.

Wake encounter -- a commuter aircraft hits the wake of a B767-200 and recovers, but changes runways to avoid any further encounters.