3.5.4 National airspace impact
tors could use the information to establish protocol and
Regulators must determine the impact of remote-
requirements. Since too much downlinked data could
sensing systems on operation of the national airspace
result in confusion rather than clarity and actually
system, air traffic control, and the Free Flight concept.
decrease the quality of information subsequently pro-
vided back to pilots, human-factors specialists should
3.5.5 Aircraft operational limits in icing
work with pilot and meteorological interests to resolve
Pilots need to know the potential intensity of icing
these problems.
ahead of their aircraft. They also need to know how
their aircraft responds to icing conditions, and they need
3.5.7 Training
to know the limits of their aircraft with regard to icing.
Training is critical to successful use of automated
FAR Part 25, Appendix C, defines icing cloud micro-
systems. It is needed to provide familiarization with
physics for aircraft design. However, if an aircraft is
systems and procedures. This will be most important
not designed specifically to fly in conditions beyond
as remote-sensing systems are initially placed in the
those described in Appendix C, it is not known whether
field to assure that pilots, air traffic controllers, and
it can safely operate in those exceedance conditions. If
operators are aware of their operational characteristics.
aircraft are not tested in conditions beyond Appendix
There is often a tendency to over-rely on technology
C, perhaps they should not be sent into those condi-
because of apparent belief in its accuracy and reliability
tions (Hill 1997).
(Transport Canada 1996). As a result, cockpit technol-
Icing risk varies with aircraft size, aircraft design,
ogy tends to reduce vigilance and situational aware-
and airfoil type. Aircraft manufacturers must identify
ness, which, in an icing environment, could be fatal.
the icing conditions that are beyond the capabilities of
Since remote-sensing technology may actually
their aircraft. Consideration must be given whether to
detach pilots from the icing threat because automation
expand Appendix C conditions or create a new FAR to
tends to increase confidence and reduce situational
address these conditions. Presently, pilots do not know
awareness, there is increasing need to promote train-
if they are flying in conditions within which the air-
ing. Training is needed on how the operational charac-
craft was tested, and they do not know if the icing being
teristics of remote-sensing systems operate and where
experienced will take the aircraft to its limits (Bettcher
their abilities and failings lie. This training should be
et al. 1996, Parelon 1996, Erickson 1997, FAA 1997).
fed by studies about the characteristics of the system,
Although it is not absolutely necessary to the function-
perhaps through work that would have been done to
ing of a remote icing-detection system, providing pilots
verify system capability (Baum and Seymour 1980).
with information about their aircraft's operational limits
In addition, there must be training on how to respond
and being able to relate information provided by sens-
when an icing warning is displayed. Human-factors
ing systems to those limits would give pilots more con-
research has addressed this issue for wind shear and
fidence about decisions to avoid or fly through icing.
terrain-avoidance systems and recently for icing (Hans-
man 1997, Vigeant-Langlois and Hansman 1999). How-
3.5.6 Weather downlinking
ever, research is needed to determine the most appro-
Onboard icing-sensing systems, through immediate
priate avoidance and escape procedures for various
and continuous downlinking, could provide forecast-
classes of aircraft in different types of airspace and
ers and numerical models with objective and timely
meteorological conditions. Establishing training stan-
temperature, liquid-water content, and drop-size infor-
dards and best management practices is a regulatory
mation that is accurate in position. Goals of forecasters
and operator responsibility.
at the NWS Aviation Weather Center are to better iden-
tify where icing is occurring, identify areas of greatest
3.6 Test beds and platforms
risk, and determine when icing conditions disappear
Efficient, cost-effective methods of testing elements
(Carle 1997). The military has similar concerns (Tucker
of remote-sensing systems, and full systems, are needed
1983, Peer 1986, Goe 1997). Downlinking of informa-
in the development stage under conditions representa-
tion gathered onboard would indicate the magnitude
tive of the operating environment. Ground-based test
and location of icing potential, indicate where there is
systems are generally less expensive than airborne plat-
no icing potential (Vigeant-Langlois and Hansman
forms, so their use should be encouraged at all stages
1999), and provide improved forecast verification. A
of development until full testing on aircraft is required.
program should be organized to formulate standards
Airborne platforms, spray tankers, and perhaps
for integrating ground, satellite, in-situ, and aircraft-
mountain-top observatories should be used to test proto-
based icing information and to establish protocol for
types of individual sensors and of entire remote-sensing
auto-reporting to ground and to other aircraft. Regula-
systems. Remote-sensing systems intended for place-
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