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A CL65 on short approach to sfo runway 28L suffers a wake turbulence encounter from the preceding B777 ahead and to the right on short final to runway 28R. The CL65 performs a go around.
| Attributes | |
| ACN | 417635 |
| Time | |
| Date | 199810 |
| Day | Sun |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : sfo airport : sfo |
| State Reference | CA |
| Altitude | agl bound lower : 400 agl bound upper : 400 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tower : sfo |
| Operator | common carrier : air carrier |
| Make Model Name | Challenger CL604 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | descent : approach landing : go around |
| Route In Use | approach : visual arrival other |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | B777 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 |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp pilot : cfi |
| Experience | flight time last 90 days : 270 flight time total : 3500 flight time type : 425 |
| ASRS Report | 417635 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | inflight encounter other other anomaly other anomaly other |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : exited adverse environment flight crew : regained aircraft control other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Weather |
| Air Traffic Incident | other |
Narrative:
We were in the process of making a visual approach to runway 28L at sfo. ATC was setting up simultaneous visuals to both runways 28L and 28R. We had previously reported a B777 in sight on visual to runway 28R. On approximately 1/4 mi final at 400 ft AGL, we experienced turbulence and uncommanded roll. PF initiated a go around. I noted FMS computed winds 035 degrees at 10 KTS. Our second visual approach and landing were normal. Wind continued to be 035 degrees at 10 KTS and up to 17 KTS. Sfo tower did ask why the 'go around.' I explained to ground control the wind situation, and how we understood that the tower controller has no way of knowing about winds at that location. I suggest that ATC make 'winds aloft' requests from the numerous FMS equipped aircraft in the area. They should then parallel approaching aircraft and match speeds. Callback conversation with reporter revealed the following information: the reporter had nothing more to add than the information supplied for the wake turbulence report. Reporter felt that had the aircraft been abreast of each other the incident would not have occurred. Initial spacing is everything, along with parallel speeds for the approach.
Original NASA ASRS Text
Title: A CL65 ON SHORT APCH TO SFO RWY 28L SUFFERS A WAKE TURB ENCOUNTER FROM THE PRECEDING B777 AHEAD AND TO THE R ON SHORT FINAL TO RWY 28R. THE CL65 PERFORMS A GAR.
Narrative: WE WERE IN THE PROCESS OF MAKING A VISUAL APCH TO RWY 28L AT SFO. ATC WAS SETTING UP SIMULTANEOUS VISUALS TO BOTH RWYS 28L AND 28R. WE HAD PREVIOUSLY RPTED A B777 IN SIGHT ON VISUAL TO RWY 28R. ON APPROX 1/4 MI FINAL AT 400 FT AGL, WE EXPERIENCED TURB AND UNCOMMANDED ROLL. PF INITIATED A GAR. I NOTED FMS COMPUTED WINDS 035 DEGS AT 10 KTS. OUR SECOND VISUAL APCH AND LNDG WERE NORMAL. WIND CONTINUED TO BE 035 DEGS AT 10 KTS AND UP TO 17 KTS. SFO TWR DID ASK WHY THE 'GAR.' I EXPLAINED TO GND CTL THE WIND SIT, AND HOW WE UNDERSTOOD THAT THE TWR CTLR HAS NO WAY OF KNOWING ABOUT WINDS AT THAT LOCATION. I SUGGEST THAT ATC MAKE 'WINDS ALOFT' REQUESTS FROM THE NUMEROUS FMS EQUIPPED ACFT IN THE AREA. THEY SHOULD THEN PARALLEL APCHING ACFT AND MATCH SPDS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR HAD NOTHING MORE TO ADD THAN THE INFO SUPPLIED FOR THE WAKE TURB RPT. RPTR FELT THAT HAD THE ACFT BEEN ABREAST OF EACH OTHER THE INCIDENT WOULD NOT HAVE OCCURRED. INITIAL SPACING IS EVERYTHING, ALONG WITH PARALLEL SPDS FOR THE 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.