Friday, July 1, 2005
Preparing for Confined-Area Ops
On Aug. 31, 2002, the pilot in command of a Sikorsky S-76 taking off from a hospital helipad became distracted by a large section of torn awning that was flapping in the wind due to rotor wash. The main rotors struck the top corner of the building and the helicopter began to settle.
The pilot said he lowered the collective and navigated between the building and the parking garage to the street below, applying full collective pitch to cushion the landing. The copilot stated that he was seated on the left side clearing for obstructions and heard a bump on the right side, followed by repetitive bumps, and saw pieces of the helicopter fly by. The copilot broke his arm when he tripped on a sidewalk while exiting. The pilot and two medical crewmembers received minor injuries.
The NTSB determined the probable cause of this accident was the flight crew's diverted attention, inadequate visual lookout and failure to ensure adequate main rotor clearance. Factors in the accident were the continued operation with known obstructions in the area and the failure of the FAA to initially certify the operation prior to its commencement.
Due to construction at the hospital, departure from this helipad required a maximum performance takeoff from a very confined area. Five days after the accident, the hospital contracted with a survey company to determine if the required obstacle clearances existed. After reviewing the results, it suspended operations for non-compliance.
The very nature of helicopters, especially in EMS operations, requires maneuvering in close proximity to objects. Not all landing sites have the benefit of a survey. Therefore, pilots must use their judgment to determine if adequate clearances and power available exists to safely land and take off. Despite the fact that a heliport doesn't meet all FAA requirements, when something goes wrong it is the pilot-in-command who bears the ultimate responsibility. The NTSB made that clear in this case. Fortunately, there were no serious injuries.
On Jan. 18, 2002, the pilot and flight nurse of a BK117 were not so lucky when their helicopter struck the hospital building at night during gusty wind conditions. The paramedic was the only survivor and said that when the helicopter was about 20 ft. above the helipad, he was programming the GPS receiver and felt a sudden gust of wind push the helicopter from 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 that extended above the height of the helipad by four floors. The paramedic yelled, "building, building, building!" to alert the pilot, who 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. The FAA inspector who examined the heliport environment a few hours after the accident stated one perimeter light on the southeast corner of the primary helipad was out of service, but sufficient lighting existed for takeoff and landing.
The U.S. National Transportation Safety Board determined the probable cause was the 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.
Lifting off from a confined area at night during gusty wind conditions requires intense concentration. What distracted this pilot will probably never be known. However, the NTSB report contains the pilot's duty time and raises an interesting issue. Although not considered a factor in this accident, fatigue can reduce a person's ability to concentrate.
A review of the pilot's duty time records revealed that he was off duty from Jan. 10-15. On Jan. 16, he worked a 12-hr. shift from 0700 to 1900. On the day of the accident, he was scheduled to work a 12-hr. shift that began at 1900 on Jan. 17 and ended at 0700 on Jan. 18. The first night shift immediately following a day shift is extremely hard on a person's circadian rhythms--the intrinsic biological clock that regulates such functions as body temperature, sleep cycles and alertness levels.
Since this accident happened at 0024 on Jan. 18, this pilot could have been awake for more than 16 hr. Studies have shown that night work interferes with circadian rhythms and can cause fatigue-induced lapses in vigilance to increase four to ten times. Moreover, the longer someone is awake beyond 14-16 hr., the greater the occurrences of lapses.
EMS helicopter pilots are always operating in and out of confined areas under very demanding circumstances. Those critical minutes while lifting off or landing demand a pilot's full and complete attention. Every preflight should include a self-assessment of one's ability to maintain a high level of alertness, particularly during take off and landing.