Page 14 - Forum-2021-JanToMarch

Why Did the Helicopter Collide

With Trees?

Investigating the Causes from

Analysis of Images and Sounds

By Koji Fukuda, Deputy Investigator for Aircraft Accidents,
Japan Transport Safety Board

urrently, 75 helicopters are operated Onsite Investigation
by 55 local governments in Japan The three investigators went to the site the
for the purpose of firefighting and next day. The accident site was on a snowy
C disaster prevention. For similar mountain, and the roads leading to the site
purposes, there are other services such as were not cleared. The large rescue vehicle
emergency medical service (EMS), police, the had reached near the site. Our rental car had
Coast Guard, and the Self Defense Force. The studless tires, so I thought it was fine, but it
firefighting disaster prevention helicopters was useless. I had to push the car many times
are operated under guidelines made by each on a road like an inclined ice rink that was
local government independently. They are hard to walk.
single-pilot operations even though they are
medium-sized helicopters of about 5 tons. Lesson 1: Select a four-wheel-drive car on snowy
The pilots are not required to have instrument roads. Not enough with studless tires.
flight licenses. And crews are not transferred
among other local government teams. This
case is an example of a firefighting and disas- Drone Investigation
ter prevention helicopter accident in which This JTSB accident investigation was the first
all nine people were killed. The helicopter was time the agency used a drone to collect onsite
not equipped with a recording device such as data. The drone was used not only to take
a black box, so the investigation required con- photographs from above the crash site, but
siderable effort to determine what occurred also allowed the investigators to create one
and why it happened. fine 2-D image (Ortho Mosaic) or 3-D images
There was a mysterious video taken on by analyzing the image data taken contin-
the aircraft that seems to show that when uously and the data of the position and the
approaching trees, the helicopter collided altitude of the drone.
with the trees without avoidance. To get a
real sense of the accident, investigators were Lesson 2: The effectiveness of the drone for
required to conduct a drone investigation and accident investigation is not just to obtain aerial
to analyze the images and sounds recorded in photos.
the video in various novel ways.
Location Survey (Laser Range Finder and
Summary of the Accident GPS Receiver)
(Adapted with permission from the On Sunday, March 5, 2017, a mid-sized rescue The position and height of the cut trees could
author’s technical paper Why Did helicopter, a Bell 412, operated by the Nagano be measured easily and clearly by using a
the Helicopter Collide with Trees? Fire and Disaster Prevention Aviation Center laser range finder (TruePulse 360, Laser
Approach the Causes from Analysis took off from Matsumoto Airport to go to Technology) and a GPS receiver (MMCX:
of Images and Sounds presented rescue training and collided with trees and Mobile Mapper CX, Magellan Navigation). As
during ISASI 2019, Sept. 3–5, 2019, in crashed into the mountain’s slope while flying described in the report, these tools enabled
The Hague, the Netherlands. The theme toward the training site near the summit the investigators to see more details of the
for ISASI 2019 was “Future Safety: accident site than what was available from
Has the Past Become Irrelevant?” at 13:33. There were nine persons on board
The full presentation can be found on the helicopter, including a captain and eight the drone investigation.
the ISASI website at www.isasi.org others, and all of them suffered fatal injuries.
in the Library tab under Technical The helicopter was destroyed, but there was Lesson 3: Easy location survey with laser and
Presentations.—Editor) no outbreak of fire. GPS. (Of course, you need tools and training.)
14 • January-March 2021 ISASI Forum