NTSB Identification: IAD02FA026.
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Accident occurred Friday, January 18, 2002 in CLEVELAND, OH
Probable Cause Approval Date: 05/13/2003
Aircraft: MBB BK-117 A-3, registration: N626MB
Injuries: 2 Fatal,1 Serious.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
The medevac helicopter lifted off the hospital's roof-top helipad at night. The pilot made a right pedal turn to the northwest, facing a building that extended above the height of the helipad by approximately 10-feet. The paramedic said that when the helicopter was about 20-feet above the helipad, and while he was programming the GPS receiver, a "sudden gust" of wind push the helicopter from directly behind. He was not alerted to anything unusual until he looked up and noticed the helicopter's close proximity to a 16-floor brick building, located at the northern corner of the heliport, which extended above the height of the helipad by 4 floors. The paramedic yelled, "building, building, building!" to alert the pilot. The pilot then made a rapid right cyclic input to avoid hitting the building, but the helicopter struck the building, and fell about 13 floors to ground level. The paramedic did not see or hear any warning lights, horns or unusual noises, and was not aware of any mechanical problems with the helicopter. A police officer who flew two missions in the local area prior to the accident said the wind speed at 500 feet agl was at least 25 knots and gusting from the south/southwest. He stood on the primary helipad after the accident and said mechanical turbulence from the building was evident. An FAA inspector who also stood on the rooftop helipad after the accident said the wind gusts were about 20-30 knots from the southwest and they swirled around the heliport. Review of the helicopter flight manual revealed, "Directional controllability during take-off and landing is assured for flight condition with crosswind components up to 17 [knots].
The National Transportation Safety Board determines the probable cause(s) of this accident to be: pilot's failure to maintain directional control of the helicopter while hovering, which resulted in its collision with a building. Factors were the confined area, tail wind, and wind gusts. Full narrative available
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