© Crown copyright Met Office Use of GRIB hazard forecasts in flight planning Bob Lunnon, Aviation...

© Crown copyright Met Office

Use of GRIB hazard forecasts in flight planning Bob Lunnon, Aviation Outcomes Manager, Met Office

WAFS Science meeting, Washington, April 20th 2009


Introductory comment

• To some, this approach to using the GRIB hazard products might seem obvious

• 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

• 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

• We have more experience in forecasting CAT than other hazards, and in verifying our forecasts

• We have estimates of the “cost” of a CAT encounter

• We have done calculations on the total cost of a flight, including “cost” of CAT encounters

• 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

A B

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

Graph at bottom of plot indicates expected frequency of CAT as aircraft flies directly from A to B

A 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 islow, 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

0

200

400

600

800

1000

1200

1400

Infinity >6% >4% >2%

CAT avoidance strategy

Co

st

Cost of CATencounters

Cost of CAT avoidance

Net cost

Note that a very limited number of flights were used to generate this figure


Information needed to generate cost-benefit graph

• Information on extra distance flown for each avoidance strategy (from flight planning company)

• Information on cost of extra distance flown (from airlines)

• Information on frequency of actual CAT encounters for each avoidance strategy (from WAFC)(depends on accuracy of forecasts)

• Information on cost of CAT encounters (from airlines)


Figures used to generate cost-benefit graph• Study undertaken in 1990s

• Used Met Office Optimum route package to calculate extra distance flown, and extra time to fly additional distance

• Used then price of fuel to derive a cost

• Used verification statistics to derive frequency of CAT encounters

• Used figures from Tom Fahey for cost of CAT encounter

• Avoiding areas of high (>6%) CAT probability was financially “better” than no CAT avoidance

• 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


Questions & answers

© Crown copyright Met Office Use of GRIB hazard forecasts in flight planning Bob Lunnon, Aviation...

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