US Fatal Night HEMS Accident: Self-Induced Pressure & Inadequate Oversight

US Fatal Night HEMS Accident: Self-Induced Pressure & Inadequate Oversight

The US National Transportation Safety Board (NTSB) has determined (24 May 2018) the probable cause of a 2016 fatal helicopter emergency medical service (HEMS) accident to be:

The pilot’s decision to perform visual flight rules flight into night instrument meteorological conditions, which resulted in loss of control due to spatial disorientation. Contributing to the accident was the pilot’s self-induced pressure to complete the mission despite the weather conditions and the operator’s inadequate oversight of the flight by its operational control center.

Metro Aviation Airbus Helicopter AS350B2 Haynes Life Flight HEMS Helicopter N911GF (Credit: NTSB)

Metro Aviation Airbus Helicopter AS350B2 Haynes Life Flight HEMS Helicopter N911GF (Credit: NTSB)

The Accident Flight

Airbus Helicopter AS350B2, air ambulance helicopter N911GF, operated by Metro Aviation as ‘Life Flight 2′ for Haynes Life Flight, was based at the Troy Regional Medical Center, Alabama.  It had departed Troy at 23:26 Local Time 25 March 2016 to attend a motor vehicle accident outside Goodman, near Enterprise, Alabama.

Witnesses indicated that fog, mist, and reduced visibility existed at the site at the time of the helicopter’s arrival to collect the casualty from a farmers field.  The casualty was described by ground personnel as “bleeding from head; groggy at times; in and out of consciousness; right femur fracture fracture”.

At 00:17 Local Time 26 March 2016, the helicopter departed, destined for Baptist Medical Center Heliport, Montgomery. On board was the single pilot, two medical personnel and the casualty.  There was “slight drizzle” around the time and although there was no ground fog according to one witness “there may have been fog above the trees”.  Another witness stated there was “a heavy mist” and the ceiling was “very low, maybe 100 foot.”  Another stated that “the fog was mixed with rain” and was “kind of pretty thick.”  The NTSB say:

Review of radar data provided by the US Army from the approach control radar site at Cairns Army Airfield, Fort Rucker, about 13 nm east, indicated that, the helicopter was first identified on radar after takeoff at 0017:35. The helicopter was in a shallow left turn and climbing to 1,000 ft above mean sea level. At 0018:04, the rate of turn began to increase and continued to increase over the next 4 seconds when the helicopter reached a peak altitude of 1,100 ft. The helicopter remained at this altitude and continued the left turn until 0018:28 when the helicopter began a rapid descent. Five seconds later, radar indicated that helicopter had descended through 600 ft. Moments later, the helicopter descended below the floor of the radar coverage area, and radar contact was lost.

Metro Aviation Airbus Helicopter AS350B2 Haynes Life Flight HEMS Helicopter N911GF (Credit: NTSB)

Metro Aviation Airbus Helicopter AS350B2 Haynes Life Flight HEMS Helicopter N911GF (Credit: NTSB)

According to [the Haynes Ambulance Communication Center] HCC, the helicopter’s on-board Skyconnect satellite tracking system updated every 3 minutes, and the pilot was supposed to contact them every 15 minutes. A search was initiated when the pilot did not check in with the communications center as required… About 0700…search parties began to smell what they believed was jet fuel and eventually located the wreckage in a swampy, heavily wooded area.

The helicopter had struck trees only about ½ mile north of the motor vehicle accident site. The cause of death for all four occupants was “multiple blunt force injuries”. https://youtu.be/VbFedJ_ek_U

The Helicopter Configuration

The NTSB say:

Although the helicopter was not certificated for flight in IMC, it had sufficient instrumentation to operate in the event of an inadvertent encounter with IMC and was equipped with a helicopter terrain avoidance warning system, a night vision imaging system which included night vision goggles (NVGs), and an autopilot.

The Pilot

The pilot had been employed by Metro Aviation for about 6 months and had accumulated just 90 hours in the AS350B2 since he was hired.  His total flight experience was 5,301 hours of which 5,265 hours were as pilot in command, 474 hours were at night and 265 hours were in IMC. The NTSB comment that he did not meet currency requirements for flight in IMC at the time of the accident nor had he been trained or qualified by the operator to fly in IMC. The NTSB however concluded he was likely using NVGs during the flight as “one of the first responders who helped load the patient into the helicopter saw the pilot wearing them”.

Operational Control, Weather and Decision Making

The operator uses an Operational Control Centre (OCC) that is staffed 24 hours a day.

Communication center employees were not Metro Aviation employees; however, all the communication center employees were trained by Metro Aviation. This training was recognized in the approved Metro Aviation Training Manual and was conducted both initially and then annually for currency requirements.

Although the aircraft commander has the final authority and responsibility, operational control coordinators at the OCC are responsible for confirming whether “a flight or series of flights could be initiated, conducted, or terminated safely, in accordance with the authorizations, limitations, and procedures in their operations manual, and the applicable regulations”.  The NTSB note that:

In the case of the accident flight, the operator’s required VFR weather minimums were a 1,000-ft ceiling with a flight visibility of 3 miles.

There were two OCC personnel on duty, a trainee and a senior operational control coordinator.  The NTSB explain that due to formatting issues the coordinates for the location of the motor vehicle accident (MVA) were not compatible with their OCC Helper software.  Consequently it provided weather data close to the helicopter base (VMC) not the motor vehicle accident site (which was in IMC).  The NTSB explain that:

The trainee reported that latitude and longitude format was a common problem with OCC Helper and, at times, required OCC personnel to reformat the latitude and longitude coordinates to get the coordinates to work in OCC Helper. On the night of the accident, the incorrectly formatted latitude and longitude for the MVA site were not corrected in OCC Helper until after the helicopter had departed its base en route to the MVA site. Given the IMC weather conditions being reported, which were below the required VFR weather minimums for the flight, the OCC coordinators should have provided the pilot with additional weather information after they had correctly input the coordinates of the MVA site into the OCC Helper software; however, they did not do so. The lack of monitoring of the flight by the OCC through direct human interaction due to overreliance on mission support software and other automated aids, and the incorrectly interpreted latitude and longitude information by both the software and the operational control coordinators resulted in a loss of operational control. Although the software formatting issues were known, there was no standard operating procedure to mitigate the problem.

The pilot did have access to internet-based weather information at the helicopter’s base, but the NTSB were unable to determined what weather information the pilot reviewed before the flight.

However, text messages between the pilot and a friend and between the flight nurse on the accident flight and the same friend indicated that the pilot was aware of the possibility of encountering IMC before he departed the base for the MVA site.

Although the NTSB do not comment, it is noticeable that crew members were sending texts during the flight and while of the ground rotors running.

Further, after landing at the MVA, the pilot would have been aware that the weather conditions at the site were below the company’s VFR weather minimums. Given the weather conditions at the MVA site, the pilot should have canceled the flight or, at a minimum, contacted the OCC to obtain updated weather information and guidance.

Metro Aviation Airbus Helicopter AS350B2 Haynes Life Flight HEMS Helicopter N911GF (Credit: NTSB)

Metro Aviation Airbus Helicopter AS350B2 Haynes Life Flight HEMS Helicopter N911GF (Credit: NTSB)

However, the pilot’s fixation on completing the mission probably motivated him to depart on the accident flight in IMC, even though significantly less risky alternatives existed, such as cancelling the flight and transporting the patient by ground ambulance.

Background: Get-There-Itis

The NTSB note that FAA  Advisory Circular AC 60-22, published in 1991 on Aeronautical Decision Making (ADM) states:

…pilots, particularly those with considerable experience, as a rule always try to complete a flight as planned, please passengers, meet schedules, and generally demonstrate that they have ‘the right stuff.’

Adding:

One of the common behavioral traps identified was “Get-There-Itis.” According to the AC, “common among pilots, [get-there-itis] clouds the vision and impairs judgement by causing a fixation on the original goal or destination combined with a total disregard for any alternative course of action.” Get-There-Itis is also known as hurry syndrome, plan continuation, or goal fixation.

Background: Spatial Disorientation

The FAA Pilot’s Handbook of Aeronautical Knowledge (FAA-H-8083-25B) states:

…under normal flight conditions, when there is a visual reference to the horizon and ground, the sensory system in the inner ear helps to identify the pitch, roll, and yaw movements of the airplane. When visual contact with the horizon is lost, the vestibular system becomes unreliable. Without visual references outside the airplane, there are many situations where combinations of normal motions and forces can create convincing illusions that are difficult to overcome. ….unless a pilot has many hours of training in instrument flight, flight in reduced visibility or at night when the horizon is not visible should be avoided. …night flying is very different from day flying and demands more attention of the pilot. The most noticeable difference is the limited availability of outside visual references. Therefore, flight instruments should be used to a greater degree.… Generally, at night it is difficult to see clouds and restrictions to visibility, particularly on dark nights or under overcast. The pilot flying under VFR must exercise caution to avoid flying into clouds or a layer of fog.

Among the illusions that can occur, and potentially did in this accident, is the Somatogravic Illusion:

At night or in IMC, lacking visual clues, rapid acceleration in flight generates a strong “tilt back” sensation which the pilot interprets (incorrectly) as a pitch up, despite the fact that the aircraft may still be on the intended flight path. To correct this imagined excess climb, the pilot will push the control column forward in an attempt to return to a normal flight path. Lowering the nose can result in a rapid descent.

Sensory Illusion SkyClip Video

Sensory Illusion SkyClip Video

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