Home' RTCA Documents for Review : Guidelines for In Situ Eddy Dissipation Rate Contents 8
© 2017, RTCA, Inc.
hazardous conditions that were encountered. This allows the AOC/Flight Follower to make
lateral or vertical aircraft routing decisions to avoid areas of potentially unsafe turbulence.
For example, a crew reports that they encountered an area of significant turbulence in a
specific geographic region. The dispatcher can then correlate the turbulence PIREP with
EDR reports generated in that particular geographic region or by the PIREP aircraft itself,
and forward those to other aircraft operating in the sector. This allows the AOC/Flight
Follower to alert flight crews of the presence of potentially unsafe turbulence conditions
near, or along their intended routes of flight using objective data.
Wake Turbulence Applications
At major airports, required separations between aircraft for wake turbulence often represent
one of the primary operational constraints that must be mitigated in order to improve
capacity. Studies have shown that atmospheric turbulence is a primary mechanism to
accelerate the decay of aircraft-generated wake vortices especially near the ground
[Holzapfel, 2013]. In highly turbulent atmospheres, wake lifetimes will be much shorter
than in atmospheres with low turbulence (i.e., the state of atmospheric turbulence has a
first order effect on the wake lifetimes).
When it is known with high confidence that atmospheric conditions favorable to long-lived
wake vortices are not present, required wake turbulence separations can be safely reduced
and capacity gains realized. This applies in all phases of flight, but it is especially true for
arrivals and departures in terminal airspace. For these operations, both very strong and
very weak atmospheric turbulence impacts on wake vortex lifetimes cannot be leveraged
to provide airport capacity benefits. That is because aircraft-aircraft separations can only
be reduced due to strong turbulence until some other common constraint (i.e., runway
occupancy or minimum radar separation) becomes dominant.
Similarly, there is no need in very low turbulence conditions to increase wake turbulence
separations between aircraft that have proven to be acceptably safe over decades of use.
Hence, there is a well-defined range of commonly occurring EDR values in the terminal
area that can be exploited to reduce wake turbulence separations and enable capacity
throughput benefits. Research has shown that in this range the algorithms commonly used
for computing Mean EDR from aircraft-derived data meet or exceed performance
specifications required for wake turbulence applications [Emanuel, et al., 2017].
Automated EDR reports from aircraft significantly increase the availability of near real-
time data on state of turbulence present in the atmosphere. Reports from multiple aircraft
can be combined with forecasts and other types of data to characterize a region of the
atmosphere. EDR data from aircraft can be used both to monitor in near real-time that the
expected levels of atmospheric turbulence continue to persist and to provide valuable input
data for mesoscale meteorological forecasting models. Both ground-based air traffic
control (ATC) provided wake solutions and flight deck-based pilot decisions for avoidance
Links Archive Addressing Human Factors/Pilot Interface Issues Navigation Previous Page Next Page