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Temporary loss of aircraft control at 100 ft AGL when performing a landing on runway 9R. The flight crew of a B777 alleges a windshear problem created by the wake turbulence of a preceding aircraft landing at ord, il.
| Attributes | |
| ACN | 616357 |
| Time | |
| Date | 200405 |
| Day | Mon |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : ord.airport |
| State Reference | IL |
| Altitude | agl bound lower : 0 agl bound upper : 100 |
| Environment | |
| Weather Elements | Windshear |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tower : ord.tower |
| Operator | common carrier : air carrier |
| Make Model Name | B777 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent : approach |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | tower : ord.tower |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Flight Phase | descent : approach |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| ASRS Report | 616357 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Events | |
| Anomaly | inflight encounter : wake turbulence other anomaly other anomaly other anomaly other |
| Independent Detector | other flight crewa other flight crewb |
| Resolutory Action | flight crew : exited adverse environment flight crew : regained aircraft control |
| Supplementary | |
| Problem Areas | Weather ATC Human Performance Aircraft Environmental Factor Flight Crew Human Performance |
| Primary Problem | Environmental Factor |
Narrative:
First officer did an excellent job of saving a landing that got very ugly at 100 ft AGL. Landing runway 9R at ord, winds reported at 250 degrees at 9 KTS. I suspect that winds may have been greater than 9 KTS, but no one wants to turn the airport around due to delays. While the aircraft is certified up to 10 KTS tailwind, this is an aircraft limitation (high ground speed, float, reduced reverser effectiveness, etc). It says nothing about the effects of the wingtip vortices of the previous aircraft. The air was relatively smooth until 100 ft when gross changes came about that on a less massive aircraft or one with a smaller wing span could have been fatal. I am certain the vortices of the aircraft ahead of us were blown laterally back on the runway and forward into our landing zone. We need to examine the effects of multiple lndgs in a tailwind and rethink the inconvenience of changing runways. An accident really messes up schedules. We could have caught a wingtip if it had happened lower or was more severe. If windshear can knock a tail off, it can sure dip a wing too far close to the ground.
Original NASA ASRS Text
Title: TEMPORARY LOSS OF ACFT CTL AT 100 FT AGL WHEN PERFORMING A LNDG ON RWY 9R. THE FLT CREW OF A B777 ALLEGES A WINDSHEAR PROB CREATED BY THE WAKE TURB OF A PRECEDING ACFT LNDG AT ORD, IL.
Narrative: FO DID AN EXCELLENT JOB OF SAVING A LNDG THAT GOT VERY UGLY AT 100 FT AGL. LNDG RWY 9R AT ORD, WINDS RPTED AT 250 DEGS AT 9 KTS. I SUSPECT THAT WINDS MAY HAVE BEEN GREATER THAN 9 KTS, BUT NO ONE WANTS TO TURN THE ARPT AROUND DUE TO DELAYS. WHILE THE ACFT IS CERTIFIED UP TO 10 KTS TAILWIND, THIS IS AN ACFT LIMITATION (HIGH GND SPD, FLOAT, REDUCED REVERSER EFFECTIVENESS, ETC). IT SAYS NOTHING ABOUT THE EFFECTS OF THE WINGTIP VORTICES OF THE PREVIOUS ACFT. THE AIR WAS RELATIVELY SMOOTH UNTIL 100 FT WHEN GROSS CHANGES CAME ABOUT THAT ON A LESS MASSIVE ACFT OR ONE WITH A SMALLER WING SPAN COULD HAVE BEEN FATAL. I AM CERTAIN THE VORTICES OF THE ACFT AHEAD OF US WERE BLOWN LATERALLY BACK ON THE RWY AND FORWARD INTO OUR LNDG ZONE. WE NEED TO EXAMINE THE EFFECTS OF MULTIPLE LNDGS IN A TAILWIND AND RETHINK THE INCONVENIENCE OF CHANGING RWYS. AN ACCIDENT REALLY MESSES UP SCHEDULES. WE COULD HAVE CAUGHT A WINGTIP IF IT HAD HAPPENED LOWER OR WAS MORE SEVERE. IF WINDSHEAR CAN KNOCK A TAIL OFF, IT CAN SURE DIP A WING TOO FAR CLOSE TO THE GND.
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.