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CHAPTER 7
AIRCRAFT OVERFLIGHTS AND SAFETY
Section 1(c) of Public Law 100-91 mandates that the
National Park Service assess the safety of on-ground visitors relative to
aircraft overflights :
"The research at each such [park] unit shall provide information and
an evaluation regarding each of the following:
(1) the impacts of aircraft noise on the safety of the park system
users, including hikers, rock-climbers, and boaters...."
The NPS addressed this question through the Park Manager Survey, the
system-wide Visitor Survey, and by contacting numerous outdoor recreation
organizations who might have knowledge of the issue. Results are discussed
in the following sections.
7.1 Concerns of Park Management
Visitor safety is a major concern of NPS managers and park staff. In
order to obtain the broadest possible perspective about these concerns as
they may be related to aircraft overflights, the Park Manager Survey (HBRS,
Inc., 1993) included questions about aircraft and visitor safety.
Questionnaires were sent to 98 park managers whose units had previously
been identified as having aircraft overflight concerns. Of the 98 parks,
91 provided detailed responses. The responses provided by these managers
give insight into the nature and extent of the perceived problem in the
National Park System. Although statistical inference cannot be made to the
entire System, the NPS is confident that this information is
representative of the nature and extent of agency concerns and certainly
reflects those situations where aircraft overflights have generated a
level of management concern.
Managers were asked their opinion on how much of a problem aircraft
overflights posed to visitor and staff safety at their park. Figure 7.1
reports the results. Of the 91 parks responding, 62 percent of the
managers either said that overflights were not a safety problem, or that
they were only a slight problem. Another 20 percent indicated overflights
were a moderate safety problem. The remaining 18 percent, however,
responded that overflights were a serious or very serious safety problem.
Table 7.1 identifies the parks where serious and very serious problems are
perceived.
In the same survey, managers were also asked to provide some detail as
to the nature of their safety concerns. Table 7.2 provides an alphabetical
listing of the parks from Table 7.1, the nature of management's safety
concerns, and the type of aircraft typically involved. This table shows a
diverse range of safety issues. The NPS recommends that these situations
be investigated by the FAA.
VERY SERIOUS PROBLEM
Chaco Culture National Historic Park
City of Rocks National Reserve
Fort Vancouver National Historic Site
Gateway National Recreation Area
Glen Canyon National Recreation Area
Sequoia & Kings Canyon National Parks
Pipe Spring National Monument
Prince William Forest Park
Statue of Liberty National Monument
SERIOUS PROBLEM
Big Bend National Park
Bryce Canyon National Park
Channel Islands National Park
Fire Island National Seashore
Gulf Islands National Seashore
John Day Fossil Beds National Monument erry's Victory & International
Peace Memorial
The NPS needs to further evaluate situations where
moderate problems are perceived to exist. Moderate problem priorities
would include Hawaii Volcanoes National Park where aircraft are believed
to be flying dangerously low over visitors and molten lava and where
visitors have been struck by gravel, wind, and rotor wash and the Great
Smoky Mountains National Park where helicopters have been reported to have
spooked trail horses and the superintendent is concerned about a possible
mid-air collision.
The FAA is already looking at the safety situation in Hawaii where from
1991-1993 there have been 46 sightseeing aircraft and rotorcraft accidents
resulting in 46 injuries and 37 fatalities. FAA inspectors have
accompanied park rangers and resource managers to document instances of
inappropriate and dangerous flying over Hawaii Volcanoes National Park,
including flying through volcanic fumes and low over molten lava.
PARK SAFETY CONCERN AIRCRAFT
Chaco Cultural National Historic Park Low-flying aircraft Propeller
City of Rocks National Preserve Low-flying aircraft Jet/Propeller
Fort Vancouver National Historic Site Low-flying aircraft Jet/Propeller
Gateway National Recreation Area Visitor Safety & Aircraft Crashes
Helicopter
Glen Canyon National Recreation Area Risk of Collision Helo/Prop
Sequoia & Kings Canyon National Parks Low-flying aircraft Jet/Helo
Pipe Spring National Monument Low-flying aircraft Jet
Prince William Forest Park Low-flying aircraft Helo/Jet
Statue of Liberty National Monument Visitor Safety & damage to monument
Helicopter
Great Smokey Mountains National Park Low-flying aircraft spooked trail
horses
Collision Risk Helicopter
Helicopter
Big Bend National Park Low flying aircraft spooked trail horses Jet
Bryce Canyon National Park Low-flying aircraft Helicopter
Channel Islands National Park Low flying aircraft Propeller
Fire Island National Seashore Low flying aircraft Propeller
Gulf Islands National Seashore Aircraft landing in park Helicopter
John day Fossil Beds Nat'l Monument Low-flying aircraft Jet/Prop
Perry's Victory & International Peace Memorial Aircraft flying dangerously
close to landmark Helo/Prop
Managers were also asked to indicate the degree to which
they perceive visitors and park staff are concerned about their own safety
as a result of aircraft overflights over their park. The results are shown
in Figure 7.2. In general, the result shows that managers believe visitor
and staff concerns to be about the same. About 74 percent of the managers
felt that staff and visitors were not concerned or were only slightly
concerned about personal safety. Approximately 10 percent felt these two
groups were moderately concerned; only 6 percent of the managers felt that
visitors and staff were very or extremely concerned about safety in their
park.
The difference in perception between managers and visitors is, in part,
a function of the managers' responsibility for visitor safety, but it also
may reflect the number of crashes that have occurred in NPS areas. 1
Through the survey, managers provided a listing of aircraft incidents
(crashes) that occurred in their parks during the past 5 years. A summary
of the information provided is presented in Figure 7.3. The figure shows
the number of incidents, in terms of type of activity, reported by the
managers. This figure shows blocks of varying heights which indicate the
total number of incidents. Propeller-driven general aviation airplanes,
propeller-driven sightseeing airplanes, and military jets were the types
of aircraft most frequently involved.2
Conclusion 7.1
Relatively few park managers perceive safety concerns to park
visitors and staff from aircraft overflying their parks. Attention needs
to be given to those few parks where serious or very serious safety
issues are perceived.
7.2 Concerns of Park Visitors
Similar questions were included in the survey of park visitors that was
conducted in 1992 (McDonald et al. 1994) at 39 parks representing the
National Park System (excluding Alaska). In the mail survey that was sent
to selected survey participants were questions relating to visitors'
perceptions on safety from aircraft flying overhead.
In one series of questions, visitors were asked how hearing or seeing
aircraft affected their visit to the park. A specific question asked how
concerned they were about their safety from aircraft flying overhead. The
responses are shown in Figure 7.4. Visitors indicated their degree of
concern by selecting one of the five categories shown at the bottom of the
graph. The figure shows that 99 percent of the respondents were either not
at all or only slightly concerned. Just 1 percent of the visitors reported
being moderately concerned about their safety, and none reported being
very or extremely concerned. This is a good indicator that any safety
problems are occurring in relatively few places and very infrequently at
that. The greater degree of concern among managers as compared to visitors
is also undoubtedly related to a long term exposure to overflight
incidents and their overall responsibility for visitor safety. Short-term
visitors simply don't have that exposure or responsibility.
In a counter-question, visitors were also asked if aircraft overflights
made them feel safer in case they needed rescue. Figure 7.5 shows the
responses. For this question, 90 percent of the respondents said that
aircraft proximity did not increase their feeling of safety, or if so only
slightly. However, 10 percent of the visitors did report an increased
feeling of safety, to a "moderate", "very", or "extreme" degree.
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1. It is the understanding of the NPS that all these incidents were
reported to the FAA and investigated by the National Transportation Safety
Board (NTSB).
2 .Miscellaneous incidents include those involving ultra-light
aircraft, a glider, a hot air balloon, and a blimp whose tether line
struck the Statue of Liberty.
Conclusion 7.2
Virtually no visitors perceive concern for their safety from aircraft
overflights, an indicator suggesting that any safety problems are
occurring in relatively few places and infrequently.
7.3 Outdoor Recreation Community Concerns
In 1993 the NPS wrote to a broad array of outdoor recreation groups to
inquire whether they could identify any on-the-ground safety issues
related to aircraft overflights of the National Park System during the
last 10 years. Groups contacted included, among others, the following
organizations:
American Alpine Club The Wilderness Society
Colorado Mountain Club Sierra Club
American Mountain Guides Association National Outdoor Leadership School
Colorado Outward Bound Backcountry Horseman of America
A limited number of written and verbal responses were received. Most of
the comments dealt with the startle effect of aircraft on themselves,
clients, or friends. No serious or lasting injuries were reported. Several
comments dealt with the inherent incompatibility of horses and helicopters
and offered examples of this incompatibility. The writers of the letters
also used the opportunity to voice concern about wildlife harassment by
aircraft and the impact of aircraft on visitors' experience in remote
areas of parks.
Conclusion 7.3
Although some outdoor recreation organizations indicated a low level
of concern on safety related to aircraft overflights, this level again
suggests local or infrequent problems as well as concerns for other
types of impacts. Ensuring a segregation between helicopters and horse
traffic in some situations may be desirable.
7.4 Temporary Flight Restriction (TFR) Problems
Low-level airspace over public lands can sometimes be very busy. This
airspace can be attractive to air tour operators as well as to general
aviation. It is at these altitudes that much military tactical training
occurs. They are the same altitudes where the NPS and other land
management agencies conduct wildlife surveys, animal capture and control
flights, law enforcement flights and aerial firefighting. The potential
for conflict is significant, especially in bad fire years. In 1992, 59
airspace conflicts involving Department of the Interior aircraft were
reported. Of these, 39 were near mid-air collisions---11 with military
aircraft and 28 with civilian aircraft. Characteristically, conflicts with
military aircraft generally occur in the Western United States where there
is a concentration of military training routes and unlit operations areas.
Conflicts with civilian aircraft more often occur in the higher density
air traffic areas along the Eastern seaboard.
The FAA, Department of Defense, and Department of Interior have already
begun to work on this issue. Apparently the key to resolving this safety
problem is dissemination of the Temporary Flight Restriction (TFR)
information to pilots who are already in the air when the notice is
issued. TFR'S are issued through the FAA (Federal Aviation Regulation
91.37A) and distributed to pilots using FAA's "Notice to Airmen" (NOTAM)
system. Great numbers of these NOTAMS are issued every day dealing with a
myriad of topics which make it difficult for pilots to identify which ones
will affect their routes. This is especially true of unlit pilots who may
be flying across the country.
Communication is the crux of the issue. Direct coordination, especially
with the military would help, but it is difficult for the NPS and other
land management agencies to know with whom they should talk. A simple,
national level system is needed to rapidly disseminate airspace
information to all pilots. Progress has been made:
The Bureau of Land Management and the Forest Service are developing
a "Computer-aided Aviation Hazard Identification System" (CAHIS) to
assist natural resource agencies in planning air operations in areas
which have a high volume of military activity.
( The Department of Interior has petitioned the FAA to create a
separate and distinct transponder code to be used by natural resource
aircraft for radar identification. This transponder code would be
available in the near future.
The Department of Defense is exploring communication links for
scheduling military training routes and special use airspace.
Conclusion 7.4
As airspace over public lands becomes more congested, the potential
for conflicts is increasing. Although progress is being made in
resolving these airspace issues, the 39 near-misses in 1992 indicate
the need for improved communication links at an operational level
between FAA, Department of Defense agencies, the NPS and other land
management agencies.
7.5 Summary
There is no evidence of any serious or wide spread safety problem for
on-ground visitors or park employees tied to aircraft overflight. There
are problems in a limited number of areas that should to be addressed.
Problems in a number of other areas should be evaluated further. Only a
few managers and virtually no visitors perceived any safety problem
related to aircraft overflight. Some elements in the outdoor recreation
community expressed concern, but the incidents triggering these concerns
are probably isolated and could be dealt with in the context of a better
reporting system. Procedures and communications are currently lacking, and
this is a problem that the involved agencies can address if they are
willing to work together to prevent problems. The potential seriousness of
the situation should not, however, be ignored. On the Pacific Crest Trail
in 1988, an Oregon couple were thrown from their horses as a result of a
low level flight; the man had a fractured skull and his wife broke her
back, collarbone, and a rib.
The NPS and other land management agencies should work with the DOD and
FAA to develop procedures for use in dealing with the airspace / park use
issues that occur in complex airspace (i.e. special use airspace, unlit
operations areas and unlit training routes) especially during fire
fighting or other major incidents. important steps have been taken, but
communication at an operational level should be significantly improved. |