The National Transportation Safety Board (NTSB) on Wednesday released the results of its probable cause investigation into the deadly KOMO TV helicopter crash which occurred near Fisher Plaza in Seattle on March 18, 2014.
According to news reports about the initial incident, the helicopter had just finished refueling on top of the KOMO News helipad and was preparing to take off. After a KOMO news crew boarded and the helicopter took off, bystanders reported it started spinning counter-clockwise before falling down into the middle of Broad Street.
The helicopter crashed on top of one vehicle that was in the roadway, which caused the helicopter to catch fire and spread to a total of three vehicles. Two people – the pilot, Gary Pfitzner, and KOMO photographer Bill Strothman – were killed in the crash, and an occupant of one of the vehicles suffered serious burn injuries to over 20 percent of his body.
Now, two and a half years later, the NTSB has concluded its official investigation into the probable cause and other factors involved in the tragic crash.
Loss of Crucial Evidence in Helicopter Crash
According to the federal agency’s official report, the large-scale fire resulting from the crash destroyed crucial evidence, and therefore the results of the investigation are inconclusive. However, the agency was able to use video surveillance footage from cameras near the scene to determine that the helicopter lost a significant amount of hydraulic power in the moments leading up to the crash.
In addition to the loss of important mechanical parts as a result of the fire, the helicopter was not equipped with a flight recording device. These factors made it difficult for investigators to determine whether the pilot conducted proper pre-flight safety checks, what his exact actions were during the attempted takeoff, or what may have caused the loss of hydraulic power.
The NTSB devised three possible scenarios that might have caused the deadly crash. Below is an excerpt of the agency’s official report, which explains the “most likely scenario” based on the investigation:
Loss of pressure during the preflight hydraulic system accumulator check due to activation of the “HYD TEST” button combined with an unlocked collective stick. In this scenario, the pilot would have engaged the “HYD TEST” button and then moved the cyclic control stick to verify that the main rotor accumulators were functioning properly. If the collective stick was not locked during this check and one or more of the main rotor accumulators were depleted by the cyclic movements, the collective would have moved up rapidly. This uncommanded collective movement is caused by a design characteristic of the main rotor system in the AS350 helicopter. The uncommanded movement is prevented by engaging the collective lock as specified in the preflight checklist. Although accidents have occurred in which an unsecured collective stick moved up enough to cause an inadvertent liftoff (see NTSB accident investigations LAX01LA083 and LAX02TA299), postaccident ground testing with an exemplar helicopter showed that, at its estimated takeoff weight, the accident helicopter would not have become airborne or light on its skids due to uncommanded collective movement as a result of main rotor accumulator depletion alone.
Summary of Helicopter Crash Factors
In summarizing the ultimate probable cause of the helicopter crash, the report adds, “The loss of helicopter control due to a loss of hydraulic boost to the tail rotor pedal controls at takeoff, followed by a loss of hydraulic boost to the main rotor controls after takeoff. The reason for the loss of hydraulic boost to the main and tail rotor controls could not be determined because of fire damage to hydraulic system components and the lack of a flight recording device.”
It would appear as though there are still some important questions related to the cause of this tragic accident that may never be answered. On one hand, the agency was able to accurately determine that a lack of hydraulic pressure caused the helicopter to spin out of control. But because much of the mechanical equipment was damaged in the fire and the NTSB cannot accurately determine the pilot’s actions leading up to and during takeoff, the agency cannot say what caused the hydraulic failure.
Those who suffer injury or loss of a loved one as a result of a serious and tragic accident such as the KOMO helicopter crash often hope that the results of a federal investigation might bring closure or help hold the responsible parties accountable for their suffering. It goes without saying that victims and their families may feel disappointment in the lack of clarity provided by the NTSB report. It’s an unfortunate reality that in some cases, the civil justice system is the last remaining avenue of legal recourse for victims and their loved ones.