Special Report

RITA Bureau of Transportation Statistics

August 2010

Effects of the February 2010 Snowstorms on Airline Performance

by Jenny Guarino and Theresa Firestine

SR-021

Several snowstorms in the Northeast, Midwest, and Southeast during February 2010 disrupted air travel not only at 

airports blanketed with snow but at airports across the United States and its territories. Altogether, more than 20,000 

flights, or 4.2 percent of all flights scheduled during the 

month, were canceled due to weather. This was the highest 

weather cancellation rate for any month since the Bureau of 

Transportation Statistics (BTS) began collecting data on the 

extent and causes of cancellations in June 2003.1

1 Since June 2003, carriers that account for at least 1 percent of domestic 

scheduled passenger revenues have reported the cause for both flight 

cancellations and/or delays in the categories of weather, carrier, national 

airspace system (NAS), and security. In addition, delays are also reported 

due to late arriving aircraft that cause a subsequent flight using the same 

plane to depart late. 

The national ramifications can be seen in figure 1, which

shows the origin and destination for air travel segments2

(originating from a major airport) canceled because of 

weather on Feb. 10, 2010 – the day with the most scheduled flight disruptions in February. From the 35 major 

airports3, all flights were canceled on 510 segments, accounting for 20 percent of all scheduled departures (2,350 

flights) from the 35 airports. All flight segments departing 

2

 Segment is defined as a nonstop flight from an origin to a destination 

airport. Segments on the same air route are considered separately. 

For example, the air route from Newark Liberty (EWR) to Los Angeles 

International (LAX) and from LAX to EWR is treated as two separate 

segments.

3

 Based on 35 high-volume airports identified by the FAA in the 

Operational Evolution Partnership (OEP).

Figure 1: Air Segments on Which all Flights Departing From a Major 

Airport Were Canceled: Feb, 10, 2010

NOTE: Segments on the same air route are considered separately. For example, the air route from 

EWR to LAX and from LAX to EWR is treated as two separate segments.

SOURCE: U.S. Department of Transportation, Research and Innovative Technology Administration, 

Bureau of Transportation Statistics, Airline On-Time Performance Database, February 2010
BTS Special Report

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from two major airports – Baltimore Washington (BWI) and 

Washington Reagan (DCA), and two small airports – Long 

Island-Islip (ISP) and Atlantic City (ACY) were canceled 

due to weather. 

In looking at the impacts of weather on on-time airline 

performance in February 2010, this report uses BTS Airline 

On-Time Performance data4. Analysis shows:

• February 2010 had the greatest proportion of weatherrelated cancellations on record, with 4.2 percent of 

flights canceled (20,206 flights). The previous record 

was 2.8 percent (15,872 flights) in February 2007.

• On the peak day, February 10, 23 percent of all scheduled flights (3,932 flights) were canceled nationwide 

due mainly to the near or complete closure of several 

large Northeastern hub airports.

• Cancellations from storms over the entire month are 

estimated to have cost $80–100 million.

A Historical Look at Weather Impacts

On average, the greatest proportion of weather cancellations occur during winter months (December-February), 

when snowfall or ice storms reduce the ability of an airport 

to function properly. March and September, months characterized by seasonal changes in weather patterns, follow 

with high proportions of weather cancellations.

In months with extreme weather, weather-related cancellations account for a large proportion of total cancellations. 

Weather-related cancellations account for approximately 

4

 Refer to On-Time Performance Data located in the TranStats section 

of the BTS website at: http://www.transtats.bts.gov/Tables.asp?DB_

ID=120&DB_Name=Airline%20On-Time%20Performance%20Data&DB_

Short_Name=On-Time

Cancellations and delays in this report refer to those reported in the 

category of weather.

half of all cancellations from December through January 

and around 43 percent of all cancellations in March and 

September. The above patterns can be seen in figure 2, 

which shows the trend in these weather-related cancellations as a percent of scheduled flights and total cancellations. 

The five worst months for weather-related cancellations all 

occurred during winter (see table 1). During three of the 

five worst months, at least one high-impact storm struck the 

Northeast Corridor region (NEC) where high-volume hub 

airports are concentrated. Unusually high snowstorm activity at hub airports in the NEC during February 2010 contributed significantly to the high cancellation rate.

The severity of NEC weather events can be seen through 

the Northeast Snowfall Impact Scale (NESIS) (see box A), 

which measures the societal impact of storms. The impact 

scores for storms occurring since January 2004 are listed in 

table 2.

Figure 2: Monthly Trend in Weather-Related 

Cancellations: January 2004 – December 2009

Jan Feb Mar April May June July Aug Sept Oct Nov Dec

0.5

1

1.5

2

Percent of scheduled flights

0 0

10

20

30

40

50

60

Percent of total cancels

50

53

49

42 43

25 23 23 25 26 27 28

SOURCE: U.S. Department of Transportation, Research and Innovative 

Technology Administration, Bureau of Transportation Statistics, Airline 

On-Time Performance Database, February 2010

Table 2: High-Impact Snowstorms That Affected 

the NE Urban Corridor: 

January 2004–February 2010

Rank Year Date NESIS Score Category

7 2005 Jan. 21-24 6.80 Crippling

14 2007 Feb. 12-15 5.63 Major

17 2010 Feb. 23-28 5.11* Major

21 2010 Feb. 4-7 4.30* Major

23 2006 Feb. 12-13 4.10* Major

25 2009 Dec. 18-21 4.03* Major

26 2010 Feb. 9-11 3.93* Significant

32 2007 Mar. 15-18 2.55* Significant

37 2009 Mar. 1-3 1.65* Notable

* Preliminary 

NOTE: The number 1 ranked storm occurred on Mar. 12–14, 1993. 

This storm has an NESIS score of 13.20 and is one of only two storms 

considered extreme in terms of its societal impact. 

SOURCE: http://lwf.ncdc.noaa.gov/snow-and ice/nesis.php as of 

February 2010

Table 1: Five Worst Months for Weather-Related 

Cancellations

Weather cancellations

Rank Month

Scheduled 

flights

Total 

canceled

Percent 

canceled

1 February 2010 481,988 20,206 (6,824) 4.2 (1.4)

2 February 2007 565,604 15,872 (13,554) 2.8 (2.4)

3 January 2006 594,924 15,748 (13,782) 2.6 (2.3)

4 December 2009 529,269 9,791 (10,887) 1.8 (2.1)

5 December 2008 544,956 10,038 (16,683) 1.8 (3.1)

NOTE: Numbers in parentheses represent weather-related delays.

SOURCE: U.S. Department of Transportation, Research and Innovative 

Technology Administration, Bureau of Transportation Statistics, Airline OnTime Performance Database, February 2010.
BTS Special Report

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As seen in table 2, two major and one significant storm 

most recently struck the NEC during February 2010. These 

storms combined with storms outside of the NEC to cause 

the weather-related cancellation rate to surpass all previously recorded rates by nearly twofold. 

The lower weather-related cancellation rate seen in table 1 

for February 2007 reflects the combined effect of the number and magnitude of storm events in 2007 versus 2010. 

In the NEC alone (see table 2), the storm categorized as 

”major” in 2007 outranks both of the major storms in 2010. 

Yet, despite greater potency, the 2007 NEC storm along 

with all other storms nationwide caused proportionally more 

weather-related delays in February 2007 than in February 2010. This differential impact demonstrates how more, 

albeit less intense, storms can halt proportionally more 

scheduled flights. Each storm, as in February 2010, adds 

additional stress to an already stressed system, thus causing weather-related cancellations to become more frequent 

than weather-related delays.

The weather-related cancellation rate exceeds the weatherrelated delay rate in months with the most numerous or 

severe storms or both. This can be seen in figure 3, which 

displays the proportion of scheduled flights experiencing a 

weather cancellation or delay. As shown, weather-related 

cancellations exceed weather-related delays in September 

2004, January 2005, February 2007, September 2008, 

and January and February 2010. With the exception of the 

two Septembers (when several hurricanes disrupted flight 

operations5), these months correspond to the months with 

5

 Notably, Hurricanes Frances, Ivan, and Jeanne in September 2004 

and Hurricane Ike in September 2008. For more information on these 

hurricanes, see the 2004 and 2008 State of the Climate Hurricane 

& Tropical Storms reports published by the National Oceanic and 

Atmospheric Administration National Climate Data Center: http://www.

ncdc.noaa.gov/sotc

numerous and severe winter storms in the NEC (refer to 

table 2).

February 2010 Weather-Related Cancellations

Examining the trend of cancellations during February 2010, 

figure 4 displays the percent of flights canceled by type. As 

shown, weather-related cancellations were more prominent 

than any other cancellation type.

Weather-related cancellations in February 2010 were 

predominant due to the severe snowstorms in the NEC, 

see table 2, as well as in the Midwest and across Southern 

states. The impact of these storms on scheduled flights 

The Northeastern Snowfall Impact Scale (NESIS), developed 

by Paul Kocin and Louis Uccellini of the National Weather 

Service, ranks storms in the Northeast Corridor by societal 

impact. The NESIS scores used in ranking account for the 

physical size of the area impacted, the amount of snow, and 

the number of people living in the path of the storm. 

Storm scores are categorized as:

•	 extreme (10+)

•	 crippling (6.0–9.99)

•	 major (4.0–5.99)

•	 significant (2.5–3.99)

•	 notable (1.0–2.499)

For more information, see: http://lwf.ncdc.noaa.gov/snowand-ice/nesis.php, February 2010

Box A: The Northeastern Snowfall Impact Scale

Figure 3: Percent of Weather-Related Delays and 

Cancellations: January 2004–February 2010

(as a percent of scheduled flights)

2004 2005 2006 2007 2008 2009 2010

0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

Weather−related delays (%)

Weather−related cancellations (%)

SOURCE: U.S. Department of Transportation, Research and Innovative 

Technology Administration, Bureau of Transportation Statistics, Airline 

On-Time Performance Database, February 2010

Figure 4: Percent Canceled Flights Nationally: 

February 2010

(as a percent of scheduled flights)

Weather Carrier NAS

0

1

2

3

4

5

SOURCE: U.S. Department of Transportation, Research and Innovative 

Technology Administration, Bureau of Transportation Statistics, Airline 

On-Time Performance Database, February 2010
BTS Special Report

4

can be seen in figure 5, which shows the rate of weatherrelated cancellations on a daily basis.

Weather accounted for three-fourths of total cancellations 

in February. While 4.2 percent of flights were canceled due 

to weather, the percent of scheduled flights canceled varied 

with each NEC storm. Table 3 compares the distribution 

of weather-related cancellations across the three major 

storms, the nonstorm periods, and nonweather cancellations to total flight cancellations and scheduled flights in 

February. 

As shown in table 3, the February 9–11 storm accounts 

for the greatest percent of cancellations in February 2010, 

even though it ranks only as “significant” and the least 

severe of the three storms on the NESIS. This can be 

explained by two severe snowstorms that hit the Midwest 

and Southern states during the February 9-11 NEC event. 

The first of these severe storms dumped 12.6 inches of 

snow on the Chicago O’Hare (ORD) airport on February 9. 

This storm caused 17 percent of scheduled departures and 

18 percent of arrivals to be canceled due to weather. These 

cancellations account for 4 percent of all weather cancels 

during February 9–11.

The second storm outside the NEC struck Southern states 

February 11–12. During this storm, the most significant 

cancellations occurred at Dallas Fort Worth (DFW) on 

February 11 due to record breaking snowfall (11.2 inches)6. 

As a result of this snowfall, 55 percent of departing and 

60 percent of arriving flights at DFW were canceled due 

to weather. These cancellations comprise 11 percent of all 

weather-related cancellations during the February 9–11 

period. A greater share of cancellations occurred on February 11 at DFW even though a nearly equal amount of snow 

fell at ORD due to DFW receiving nine times7 its February 

snowfall average. 

February 10, 2010 

The peak day for weather-related cancellations across all 

airports was February 10 when 23 percent of all scheduled 

flights (3,932 flights) were canceled. All flights departing from and arriving at Washington Reagan (DCA) were 

canceled and 85 percent or more were canceled due to 

weather at John F. Kennedy (JFK), La Guardia (LGA), 

Dulles (IAD), Newark Liberty (EWR), Philadelphia (PHL), 

and Baltimore Washington (BWI) (see figure 6). The weather-related cancellations at these airports accounted for 87 

percent of all weather-related cancellations on February 

10—1,750 scheduled departures and 1,735 scheduled arrivals.

6

 For snowfall records, see: http://www.ncdc.noaa.gov/extremes/records.

php. For more information on daily snowfall amounts, see: http://www7.

ncdc.noaa.gov/CDO/georegion

7

 The mean February snowfall from 1971 to 2000 at DFW is 1.2 inches 

(http://cdo.ncdc.noaa.gov National Weather Service Climate Normals 

1971-2000 CLIM20-02)

Figure 5: Percent of Weather-Related 

Cancellations Nationally, by Date: February 2010 

(as a percent of scheduled flights)

1357 9 11 13 15 17 19 21 23 25 27

0

5

10

15

20

25

Day of month

SOURCE: U.S. Department of Transportation, Research and Innovative 

Technology Administration, Bureau of Transportation Statistics, Airline 

On-Time Performance Database, February 2010

Table 3: Nationwide Cancellations: February 2010

Cancellations Count

Percent of all 

cancellations

Percent of all 

flights

Weather cancels 20,206 76.88 4.19

 Storm 1 (Feb 4-7) 4,053 15.42 0.84

 Storm 2 (Feb 9-11) 8,208 31.23 1.70

 Storm 3 (Feb 23-28) 3,693 14.05 0.77

 All other days 4,252 16.18 0.88

Nonweather cancels 6,075 23.12 1.26

NOTE: There were 26,281 cancellations and 481,988 scheduled flights in 

February 2010. Storms correspond to those listed on NESIS (table 2).

SOURCE: U.S. Department of Transportation, Research and Innovative 

Technology Administration, Bureau of Transportation Statistics, Airline OnTime Performance Database, February 2010

Figure 6: Major Airports Where the Percent of 

Arriving and Departing Flights Canceled Due to 

Weather Exceeded 50 Percent: Feb. 10, 2010

Logan Intl, MA (BOS)

John F. Kennedy, NY (JFK)

La Guardia, NY (LGA)

Dulles, DC (IAD)

Newark Liberty, NJ (EWR)

Philadelphia, PA (PHL)

Baltimore, MD (BWI)

Ronald Reagan, DC (DCA)

Weather−related arrival/

departure cancellation rate

Number of arriving/departing 

flights canceled due to weather

100% 453

521

483

510

524

370

400

624

99%

99%

97%

96%

92%

86%

65%

SOURCE: U.S. Department of Transportation, Research and Innovative Technology Administration, Bureau of Transportation Statistics, Airline On-Time 

Performance Database, February 2010
BTS Special Report

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For more information regarding airport variation in weatherrelated cancellations and delays throughout February, refer 

to the supplementary materials on the BTS website8. 

Cost of the February 2010 Storms

The February storms did not strike carriers without a cost. 

In particular, the severe weather events resulted in revenue 

lost not only from cancellations but also from delays. The 

total cost of cancellations is not known, as the potential 

lost revenue varies across carriers due to the severity of 

local weather events and carriers’ ability to rebook. Across 

all carriers, analyst Helane Becker, from Jesup & Lamont, 

estimates a total of $80 – 100 million in revenue lost to the 

February 2010 storms9.

8

 For supplementary materials, see: http://www.bts.gov/publications/

special_reports_and_issue_briefs/special_report/2010_07/pdf/

supplemental.pdf

9

 Mary Jane Credeur and Mary Schlangenstein. “US Airways, Delta Lead 

Traffic Decline on Storm Cancellations,” BusinessWeek, 9 March 2010:

The total cost of February 2010 storms in terms of delays 

can be estimated based on the direct aircraft operating 

cost per block minute, which according to the most recent 

(calendar year 2008) estimate from the Air Transport Association is $60.9910. Applying this cost to total weather delay 

minutes in February 2010 (307,997 minutes) leads to an 

estimated cost of $18.8 million. This cost underestimates 

the true cost as it does not include the cost of weather 

delays on airline customers, e.g., from lost productivity, 

wages, etc. 

10 Air Transport Association, costs of delays: http://www.airlines.org/pages/

home.aspx

About This Report For Related BTS Data and Publications: www.bts.gov

This article was prepared by Jenny Guarino, 

a Mathematical Statistician in the Bureau of 

Transportation Statistics (BTS), and Theresa 

Firestine, an Economist in BTS. BTS is 

a component of the U.S. Department of 

Transportation’s Research and Innovative 

Technology Administration (RITA). Both authors 

contributed equally.

Special thanks to the BTS Office of Airline 

Information, Alan Jeeves at BTS, and Dan Murphy, 

Akira Kondo and Nan Shellabarger at the FAA for 

their rigorous reviews.

For questions about this, or other BTS special reports, 

call 1-800-835-1351, email answers@bts.gov, or visit 

www.bts.gov.

DataThis special report is based on data from monthly Airline 

On-Time Performance data reported to the Bureau of 

Transportation Statistics (BTS):

• http://www.transtats.bts.gov/