Narrative:

We were cleared for the visual approach. When we were on a 2 mi final; tower told us that a helicopter was crossing the runway at about 1000 ft from the threshold. We could see a blackhawk helicopter at about 100 ft AGL cross the runway over the 1000 ft runway aiming point marking. Neither me nor my first officer gave the helicopter a second thought. As we crossed the runway threshold and prior to the 1000 ft fixed distance marker; the airplane suddenly dropped and we slammed onto the runway. Up until that point we were on a stabilized approach. I had not made any confign; pitch; or thrust changes up to that point. Our airspeed was constant with a steady wind that was right down the runway at about 15 KTS. I then realized that we had hit the wake of the blackhawk helicopter. I have never experienced wake from a helicopter before and this caught me completely off guard. It happened so fast I was not able to react in time to prevent the aircraft from slamming onto the runway. To prevent this from happening in the future; ATC should not be permitted to cross helicopters at low altitudes over the touchdown zone of the landing runway.

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Original NASA ASRS Text

Title: EMB135 FLIGHT CREW EXPERIENCES A HARD LANDING AFTER ENCOUNTERING UNFORESEEN BLACKHAWK HELICOPTER'S WAKE TURBULENCE.

Narrative: WE WERE CLRED FOR THE VISUAL APCH. WHEN WE WERE ON A 2 MI FINAL; TWR TOLD US THAT A HELI WAS XING THE RWY AT ABOUT 1000 FT FROM THE THRESHOLD. WE COULD SEE A BLACKHAWK HELI AT ABOUT 100 FT AGL CROSS THE RWY OVER THE 1000 FT RWY AIMING POINT MARKING. NEITHER ME NOR MY FO GAVE THE HELI A SECOND THOUGHT. AS WE CROSSED THE RWY THRESHOLD AND PRIOR TO THE 1000 FT FIXED DISTANCE MARKER; THE AIRPLANE SUDDENLY DROPPED AND WE SLAMMED ONTO THE RWY. UP UNTIL THAT POINT WE WERE ON A STABILIZED APCH. I HAD NOT MADE ANY CONFIGN; PITCH; OR THRUST CHANGES UP TO THAT POINT. OUR AIRSPD WAS CONSTANT WITH A STEADY WIND THAT WAS RIGHT DOWN THE RWY AT ABOUT 15 KTS. I THEN REALIZED THAT WE HAD HIT THE WAKE OF THE BLACKHAWK HELI. I HAVE NEVER EXPERIENCED WAKE FROM A HELI BEFORE AND THIS CAUGHT ME COMPLETELY OFF GUARD. IT HAPPENED SO FAST I WAS NOT ABLE TO REACT IN TIME TO PREVENT THE ACFT FROM SLAMMING ONTO THE RWY. TO PREVENT THIS FROM HAPPENING IN THE FUTURE; ATC SHOULD NOT BE PERMITTED TO CROSS HELIS AT LOW ALTS OVER THE TOUCHDOWN ZONE OF THE LNDG RWY.

Data retrieved from NASA's ASRS site as of May 2009 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.