Standard takes on the
challenge of defining how UAVs sense and avoid other aircraft
One of the challenges inherent in the design and construction of
unmanned aerial vehicles (UAVs) is to establish the fundamental
design and performance specifications for an airborne
sense-and-avoid (S&A) system. As its name implies, a
sense-and-avoid system would sense the presence of other aircraft
in nearby airspace, and would take steps to divert the UAV from the
other aircraft in accordance with Federal Aviation Administration
(FAA) requirements. A new standard developed by ASTM
Committee F38 on Unmanned Air Vehicle Systems addresses the issues
involved in designing S&A systems.
The standard, ASTM F2411, Specification for Design and
Performance of an Airborne Sense-and-Avoid System, outlines
specific parameters that are essential for any mechanical system
that is designed to take the place of a human pilot while still
maintaining an equivalent level of safety to that pilot. It also
provides a single definition for equivalence that can be applied to
all UAVs that require sense-and-avoid capability.
"By addressing these
issues, the standard sets a performance threshold for the
technology as well as the fundamental methods to prove compliance,"
says Ryan Schaefer, senior systems engineer, SRA International, and
member of Subcommittee F38.01 on Airworthiness. He also notes
that the subcommittee welcomes any comments or participation from
parties interested in this standard or others currently being
developed.
UAVs currently must operate in the National Airspace System with
special authorization from the FAA. This permission, which is
called a Certificate of Authorization, is contingent upon a list of
requirements, one of which is that a UAV operator must provide a
method to sense and avoid other aircraft. While this can be
satisfied in a variety of ways -- ground observers, radar coverage,
or a manned chase plane -- these methods are not always
cost-efficient or mission-appropriate. Adding a sensor to the
UAV platform is a viable solution, but no onboard sensor has yet
been certified by the FAA for UAV sense-and-avoid.
"An S&A standard
was needed for the industry to move forward, a standard to which
all classes of UAV can demonstrate compliance," says
Schaefer. "This standard is a first step down the road of
getting FAA approval for UAV S&A sensors and, ultimately, UAV
'file-and-fly' access to the national airspace similar to the
process for manned aircraft."
Although initial users of the S&A specification will be
within the UAV community, Schaefer says it was designed to address
the overall problem of collision avoidance in national
airspace. Because of this, Schaefer feels that the standard
will also be useful by the manned aviation community to develop
S&A systems that assist human pilots in avoiding mid-air
collisions.