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# Use of GRIB hazard forecasts in flight planning

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Use of GRIB hazard forecasts in flight planning
Bob Lunnon, Aviation Outcomes Manager, Met Office
WAFS Science meeting, Washington, April 20th 2009
Introductory comment
вЂў To some, this approach to using the GRIB
hazard products might seem obvious
вЂў However, there needs to be very effective
dialogue between the various stakeholders
(including WAFCs, flight planning companies,
airlines, regulators) for cost-effective use of the
products to be possible
вЂў We have an opportunity to ensure that all
concerned collaborate to ensure optimum use
of the products
Use forecast of CAT as an
example for other hazards
вЂў We have more experience in forecasting CAT
than other hazards, and in verifying our
forecasts
вЂў We have estimates of the вЂњcostвЂќ of a CAT
encounter
вЂў We have done calculations on the total cost of a
flight, including вЂњcostвЂќ of CAT encounters
вЂў Approach can be extended to other hazards
(Cb, icing) if costs are known
Flying from A to B through area of
forecast high frequency of CAT
A
B
Black in centre of plot indicates area of high frequency of CAT
Dark grey in plot indicates area of moderate frequency of CAT
Light grey in plot indicates area of low frequency of CAT
This graphic could be either a map or a cross-section
(later we will assume it is a map)
Possible strategies for avoiding
areas where forecast CAT is
above some threshold
A
B
Can in principle choose routes which tangentially touch
areas where CAT frequency is above some threshold
(with Met Office optimum route system can do this)
Most flight planning systems consider
a network of fixed routes
B
A
Here we show only routes which realistically might be
chosen when flying from A to B
(Network of routes may be different scale to CAT areas)
Consider direct route from A to B
A
B
Graph at bottom of plot indicates expected frequency
of CAT as aircraft flies directly from A to B
Consider route chosen to
maximise CAT avoidance
Graph at bottom of plot indicates expected frequency
of CAT as aircraft flies from A to B along indicated route
Compare routes
Information in graphs should be generated by
flight planning companies and fed to airlines/pilots
Costs of CAT encounters and
CAT avoidance
If fly round light grey area, cost of CAT encounters is
low, cost of CAT avoidance is high
If fly round black area, cost of CAT encounters is
high, cost of CAT avoidance is low
It should be possible to identify CAT avoidance
strategy which minimises total cost
CAT avoidance
CAT cost benefit diagram
1400
1200
Cost
1000
Cost of CAT
encounters
800
Cost of CAT avoidance
600
Net cost
400
200
0
Infinity
>6%
>4%
>2%
CAT avoidance strategy
Note that a very limited number of flights
were used to generate this figure
Information needed to
generate cost-benefit graph
вЂў Information on extra distance flown for each
avoidance strategy (from flight planning
company)
вЂў Information on cost of extra distance flown
(from airlines)
вЂў Information on frequency of actual CAT
encounters for each avoidance strategy (from
WAFC)(depends on accuracy of forecasts)
вЂў Information on cost of CAT encounters (from
airlines)
Figures used to generate
cost-benefit graph
вЂў Study undertaken in 1990s
вЂў Used Met Office Optimum route package to calculate
extra distance flown, and extra time to fly additional
distance
вЂў Used then price of fuel to derive a cost
вЂў Used verification statistics to derive frequency of CAT
encounters
вЂў Used figures from Tom Fahey for cost of CAT encounter
вЂў Avoiding areas of high (>6%) CAT probability was
financially вЂњbetterвЂќ than no CAT avoidance
вЂў Our forecasts have improved since then!
Use of hazard data in airline
flight planning systems
For any route under consideration calculate time to fly,
conventional cost, fuel, as at present
For any route, calculate average forecast CAT frequency
Using data from WAFC, calculate expected frequency
of CAT encounters for all prospective routes
Derive cost of CAT encounters for all prospective routes
Optimum routes westbound for
10/12/2008, from 5/12/2008