Anatomy of Weather Delay: Impact of Severe Weather on NAS Operations

Agam N. Sinha May 16, 2001

© 2001 The MITRE Corporation. All Rights Reserved.

What was the major operational issue? (Scenario courtesy of Jack Kies, FAA Acting ATT-1)

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© 2001 The MITRE Corporation. All Rights Reserved.

What was the major operational issue? (Scenario courtesy of Jack Kies, FAA Acting ATT-1)

It was this!

Not this!

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© 2001 The MITRE Corporation. All Rights Reserved.

Outline • Two sample days – April 9, 2001: The National Airspace System (NAS) Copes with Stormy Weather – June 14, 2000: Unpredicted Weather Disrupts the NAS

• For each day – Forecast versus actual weather – NAS response

• NAS performance statistics

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© 2001 The MITRE Corporation. All Rights Reserved.

April 9, 2001 - The NAS copes with stormy weather

•• Afternoon Afternoonand andevening evening thunderstorms thunderstormsforecast forecast •• Ground Groundstops stopsand anddelays delays called calledin inthe theNortheast Northeast •• Storms Stormsblock blockportions portionsof of Northeast Northeastcorridor corridor •• Air Airtraffic trafficrerouted reroutedaround around thunderstorms thunderstorms

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5 pm: Thunderstorms move east. Forecast ahead of storms.

ORD

LGA

STL

ATL

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7 pm: Storms move into NE corridor. Forecast catches up, but misses tail.

ORD

LGA

STL

ATL

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9 pm: NE corridor becoming blocked. Dense coverage over NY and DC airports.

ORD

LGA

STL

ATL

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11 pm: NE corridor opens up. Storm front moves out to sea.

ORD

LGA

STL

ATL

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Key : Ground Stop

: Ground Delay Program

As a result of FAA/users collaboration 10

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5 pm: Air traffic flows smoothly as storm travels east of Cleveland.

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7 pm: Traffic rerouted south of thunderstorm.

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9 pm: Storm passes over major East Coast airports

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11 pm: Traffic resumes through Cleveland center as storm moves out to sea

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June 14, 2000 - Unpredicted weather disrupts the NAS •• Unpredicted Unpredictedthunderstorms thunderstorms across acrossthe theSoutheast Southeast •• Fog Fogand andlow lowvisibility visibilityin inthe the Northeast Northeast •• NAS NASreacts reactsto tounpredicted unpredicted weather weather •• NAS NASperformance performanceseverely severely disrupted disrupted

Fog/Visibility

Unpredicted T-storms

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3 pm: Storms in the Southeast are worse than predicted.

ORD

LGA

STL

ATL

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5 pm: Storms blanket the Southeast.

ORD

LGA

STL

ATL

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7 pm: Forecast catches up to weather.

ORD

LGA

STL

ATL

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10:30 am: East coast flows normal. Chicago

New York

Dallas

Atlanta

1:30 pm: Local weather begins to disrupt traffic Chicago

New York

East-west flows affected

Dallas

Atlanta

2 pm: Traffic rerouted to the south. Chicago

New York

Dallas

Atlanta

3 pm: Traffic flows through gap in storms. Chicago

New York

Dallas

Atlanta

4 pm: Gap closes, blocking rerouted traffic. Chicago

New York

Atlanta

Dallas IAH

4:30 pm: New gap opens. Traffic volume well below normal. Chicago

New York

Dallas

Atlanta

Hours of peak impact 7:00 pm, April 9, 2001

4:30 pm, June 14, 2000

New York

New York

Atlanta

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Corridors north and south of storm well utilized

Atlanta

Flow impeded as gaps in unpredicted weather close

© 2001 The MITRE Corporation. All Rights Reserved.

NAS Performance: # of Flights Delayed Greater Than 15 Minutes 3000

# of Flights

2250

1500

750

0 14-Jun-2000

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9-Apr-2001

Summer 2000 Average

© 2001 The MITRE Corporation. All Rights Reserved.

NAS Performance: Cancellations

# of Cancellations

1800

1350

900

450

0 14-Jun-2000 27

9-Apr-2001

Summer 2000 Average © 2001 The MITRE Corporation. All Rights Reserved.

Summary

• Severe weather will cause disruptions • Good forecasts help minimize the impact -- but the fundamental science of 2-6 hours forecast of convective weather is limited • Collaboration among users and FAA facilities is the key to managing the impact of weather.

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© 2001 The MITRE Corporation. All Rights Reserved.