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.

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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.