MD11 freighter cleared for bay visual approach at sea, to follow a B757. Flight crew interpretation of clearance was that they could provide their own in trail separation from B757 ahead. Controller asked when they were going to turn.

Home

Browse by month

Random

Latest

About

Contact

Attributes
ACN	364920
Time
Date	199703
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : sea
State Reference	WA
Altitude	msl bound lower : 3000 msl bound upper : 3000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sea
Operator	common carrier : air carrier
Make Model Name	MD-11
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other descent : approach
Route In Use	approach : visual arrival other enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent : approach
Route In Use	approach : visual arrival other enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 150 flight time total : 13000 flight time type : 450
ASRS Report	364920
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 65 flight time total : 4700 flight time type : 300
ASRS Report	364917
Events
Anomaly	non adherence : published procedure non adherence : clearance other anomaly other other spatial deviation
Independent Detector	other controllera other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Cleared for the bay visual runway 16R at seatac airport. We were following a B757. While watching this aircraft and keeping spacing for wake turbulence we deviated from the visual procedure and overflew part of town. We should have remained over the bay. We were safe and at a high altitude so safety was not a concern. Supplemental information from acn 364917: I queried the controller on the type of aircraft we were following and it was a B757. Shortly after, approach control asked us if we had the airport and traffic at 1 O'clock, which we had. We were then cleared for the bay visual approach for runway 16R. Because the reputation of the B757, we extended our downwind/dogleg turn north of elliott bay and ATC asked us when we were going to turn. Our modified base/dogleg intercepted the final approach course approximately 2 mi outside parkk/LOM. Our perception to the issuance of a visual approach clearance behind traffic put the responsibility on us to adequately space our aircraft so we don't encounter the B757's highly notorious wake turbulence.

Original NASA ASRS Text

Title: MD11 FREIGHTER CLRED FOR BAY VISUAL APCH AT SEA, TO FOLLOW A B757. FLC INTERP OF CLRNC WAS THAT THEY COULD PROVIDE THEIR OWN IN TRAIL SEPARATION FROM B757 AHEAD. CTLR ASKED WHEN THEY WERE GOING TO TURN.

Narrative: CLRED FOR THE BAY VISUAL RWY 16R AT SEATAC ARPT. WE WERE FOLLOWING A B757. WHILE WATCHING THIS ACFT AND KEEPING SPACING FOR WAKE TURB WE DEVIATED FROM THE VISUAL PROC AND OVERFLEW PART OF TOWN. WE SHOULD HAVE REMAINED OVER THE BAY. WE WERE SAFE AND AT A HIGH ALT SO SAFETY WAS NOT A CONCERN. SUPPLEMENTAL INFO FROM ACN 364917: I QUERIED THE CTLR ON THE TYPE OF ACFT WE WERE FOLLOWING AND IT WAS A B757. SHORTLY AFTER, APCH CTL ASKED US IF WE HAD THE ARPT AND TFC AT 1 O'CLOCK, WHICH WE HAD. WE WERE THEN CLRED FOR THE BAY VISUAL APCH FOR RWY 16R. BECAUSE THE REPUTATION OF THE B757, WE EXTENDED OUR DOWNWIND/DOGLEG TURN N OF ELLIOTT BAY AND ATC ASKED US WHEN WE WERE GOING TO TURN. OUR MODIFIED BASE/DOGLEG INTERCEPTED THE FINAL APCH COURSE APPROX 2 MI OUTSIDE PARKK/LOM. OUR PERCEPTION TO THE ISSUANCE OF A VISUAL APCH CLRNC BEHIND TFC PUT THE RESPONSIBILITY ON US TO ADEQUATELY SPACE OUR ACFT SO WE DON'T ENCOUNTER THE B757'S HIGHLY NOTORIOUS WAKE TURB.

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.