Page 26 - Forum-2020-JulyToSeptember

controlled airspace. The air safety inves- that have become embedded in aviation unlikely might an RPAS CFIT be?
tigator simply would ask why the former thinking through decades of experience Runway environment hazards pose a
was operating under less-stringent re- and common practice, including some different set of challenges for unmanned
quirements than the latter and place the based on accident experience. As such, it aircraft. C2 links tend to be band-
decision made and their consequences does not readily highlight certain types width-hungry, meaning only flight-critical
in their proper chronological perspec- of accidents whose underlying causes functionalities might be in the “protected
tive. might derive from the uniqueness of spectrum.” If the only camera aboard is
However, if one applies the principles UAS, except in very general terms. Some part of an unmanned aircraft’s payload, it
of system safety in reverse, it is clear that creative thinking, and a fairly detailed may not be available for ground oper-
rules and training typically are the last understanding of how UAS work, must be ations or may not provide an adequate
hazard controls to be imposed on a sys- applied to “occurrence-based” templates. field of view for safe taxiing. If towed into
tem. They typically are far less effective This may be done prior to or in the midst position on an active runway, RPAS may
than those associated with earlier stages of an accident investigation, but some interfere with other operations or require
in the life cycle—developing warning preparation is needed to engage in such other aircraft to yield to them.
systems, modifying a system to eliminate “what if” strategizing effectively. On final approach, an unmanned
a hazard, or, most desirably, designing As an example, the current emphasis aircraft may directly observe its touch-
the system to avoid encountering the of ICAO’s Global Aviation Safety Plan down point, or it may fly in a more or
hazard in the first place. is on improving runway safety, reduc- less purely automated mode to a GPS-de-
Many of the design decisions that ing controlled flight into terrain (CFIT) fined touchdown point. In other words,
have resulted in unmanned aircraft not accidents, and reducing loss of control mixed UAS and manned operations at an
having air traffic–related avionics—or in in-flight accidents. EUROCONTROL airfield could result in a whole range of
some cases lacking redundant con- maintains lists of exemplar accidents as- challenges distinct from those that have
trols, standardized pilot interfaces, and sociated with each of the above that can occasioned such concentrated attention
other features commonly found aboard be found on www.skybrary.aero. Interest- on runway safety over time.
manned aircraft—are a direct result of ingly, these three types of accidents have Perhaps most interesting from both
how UAS are certified (or not certified). been quite resistant to preventive efforts historical and prevention perspectives
In other instances, it is the nature of over time, but not for lack of attention
unmanned aircraft themselves (lacking paid to them. in the context of unmanned aviation is
a pilot on board who can assume control For Skybrary, EUROCONTROL had no the Skybrary recap of causes seen in a
of an aircraft in an emergency, directly difficulty assembling a representative list whole range of “loss of control–inflight”
perceive the environmental conditions of fatal CFIT accidents solely from oc- (LOC-I) accidents, which includes all of
affecting it, etc.) that can result in an currences since the beginning of the 21st the following:
unmanned aircraft becoming unrecov- century. The list of runway operations • Loss of situational awareness.
erable, experiencing a progressively dete- accidents is much longer and includes • Low-level wind shear or higher-level
riorating condition or system failure, or a number of events that fairly may be clear air turbulence.
otherwise operating in a manner counter considered “landmark accidents,” e.g., the
to that intended. For these reasons, it is Tenerife tragedy, a Boeing 737 landing • Structural or multiple powerplant
worthwhile to consider outcomes—some on top of another aircraft in Los Angeles, damage (including that suffered dur-
ing midair collisions).
of which have been declining steadily for California, U.S.A., and other accidents
decades—against potential new sources involving occupied runways and miscues • Intended or unintended mishandling
of failures or initiating events that can by pilots and/or air traffic controllers. of the aircraft.
lead to those outcomes. CFIT accidents would seem to be • Attempted flight with total load or
Most categorization approaches to ac- unlikely in routine RPAS operations, load distribution outside of safe
cidents have relied on identifying types especially those using platforms that are limits.
of events that the aviation community equipped with comprehensive position • Unintentional mismanagement of air-
wants to reduce or prevent. For example, tracking provided to their RPICs. Now, craft pressurization systems.
the CAST (Commercial Aviation Safety think about what happens if the com- • Takeoff attempts with ice contami-
Team)-ICAO Common Taxonomy Team mand and control (C2) link fails and the nation.
list of aviation occurrence categories aircraft reverts to a preprogramed mode
includes more than 30 types of events. of operation (“lost link profile”). Terrain • Airframe ice accumulation/signif-
Only about half of these would seem to awareness and warning systems (TAWS) icant loss of power attributable to
be of importance to regulators or RPAS are neither typically provided nor man- engine icing
operators simply because they do not dated for any type of RPAS. So given that a • Attempting to maneuver an aircraft
have to worry about the lives of peo- C2 link failure takes the RPIC entirely out outside its capabilities to resolve a
ple aboard their aircraft (yet), and the of the control loop, and the aircraft might prior problem.
latter’s risk tolerance for certain types of “decide” to take up a heading, airspeed, • In-flight fire.
losses is correspondingly higher. and altitude from its present position that • Fuel exhaustion or starvation.
At the same time, this taxonomy, like would take it to a preprogramed point in
so much of the current aviation enter- space, regardless of the possibility of in- • False instrument readings.
prise, is based on certain assumptions tervening terrain or surface features, how • Wake turbulence.
26 • July-September 2020 ISASI Forum