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Emergency Medical Service (EMS) calls are not nearly
so dramatic. However, the operational aspects of EMS
calls can be the ultimate test of a helicopter pilot’s skills.
The “scene” calls that may have contributed to the
victim’s injuries—a vehicle accident, a near-drowning
or serious fall at a rocky beach, a backwoods hunting
accident, or an aircraft forced-landing in mountainous
terrain—also contribute to the risk associated with the
EMS flight. Yet these are precisely the situations in
which a helicopter may be the most expeditious, or even
the only, means of getting medical assistance to the
victim and getting the victim to a medical facility.
The first hour following a serious injury is the most
time-critical period, during which the patient mortality
rate can be reduced by as much as 50 percent if immediate
and appropriate medical care can be provided. The
benefits of immediate treatment by medical personnel
at an on-scene emergency and rapid transport of the
patient, especially within this “golden hour,” have been
well-documented. Hospitals and medical centers have
recognized the value of pairing medical crews and
helicopters for reaching critically-injured or seriouslyill
patients. As a result, the number of hospital helicopter
programs has increased dramatically over the last
ten to fifteen years.
Issue Number 6 13
During the years 1978-1986, this increased use of helicopters
for emergency medical and air ambulance services
came at a high price. In a study of 59 EMS
accidents during this period, the NTSB found that the
accident rates for EMS helicopter operations were approximately
3.5 times higher than for other non-scheduled
Part 135 Air Taxi helicopter operations. Human
error, directly or indirectly, was attributed as the cause
of the majority of these accidents. To the credit of the
EMS industry, these accident rates decreased significantly
following the NTSB report and recommendations.
A recent study undertaken by NASA and the Aviation
Safety Reporting System (ASRS) looked at 81 incident
reports submitted from 1986 to 1991 involving EMS
helicopters. The purpose was to identify and describe
the operational aspects of these incidents, and to assess
the contribution of human factors to these occurrences.
This article will focus on the human factors most commonly
cited: communication interactions, time pressure,
distraction, and workload.
Can We Talk…?
Communication and information transfer difficulties
were pervasive, and repeatedly emerged as a major
contributor to the chain of events leading to the reported
incident (78 percent). The most common difficulties
were reported as miscommunication during pilot
contact with ATC and unsuccessful attempts by a pilot
to contact ATC. Further, pilot communications with
other pilots, hospital dispatchers, and ground personnel
(i.e., police, firefighters, paramedics, park rangers,
etc.) were also cited as additional interactions which
sometimes interfered with ATC communication:
✍ “I was coordinating with dispatcher, medic command
(flight following/status reports), and emergency
vehicle on scene, and broadcasting position
reports and intentions on Unicom. Approach advised
(me) that I entered his airspace and did not properly
coordinate with his controller… I was working four
frequencies and receiving conflicting coordinates from
the ground while searching for the landing zone.”
(ACN 181754)
Communications problems played a major role in reports
of both airspace violations and near mid-air collisions
(NMACs), which occurred most frequently in
Class D airspace during early- to mid-afternoon (1201-
1800 hours). This is a reflection of the complex, controlled-
airspace environment found in the areas that
can support major medical centers, and also the time of
day when air traffic is generally heavy and inter-facility
patient transfers are most likely to take place.
In 50 percent of airspace violations and 59 percent of
NMACs, the EMS pilot was in radio communication
with at least one ATC facility at the time of the incident.
Frequency congestion, misunderstanding of ATC instructions
or clearances, busy ATC personnel, and lack
of common understanding of the “Lifeguard” call sign
priority were cited as problems affecting the information
transfer process, and contributing to the reported
incident. (See sidebar).
Airspace violations frequently occurred during the takeoff
phase of flight and were often due to poor radio
　
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