Flight Cancellations and Delays

Data Analyst Nanodegree - Project 6

Cheng Wang

Data Set

United State flight delays and performance data set is from RITA. The clean data set for 2008 is download from here. Flight cancellation and delay information in 2008 are explored in this report.

Flight Cancellations

The flight cancellation rate (number of cancelled flights over number of total flights) for each month in 2008 is shown as stacking bar in Figure 1. We can see that January to March and December have high cancellation rate comparing to other months. In addition, we also can see the flight cancellation rate by extreme weather are also high in these months. It makes sense that the high cancellation rate in winter season could be caused by the snow.

However, the cancellation caused by weather in September is also high. In order to find the reason of high cancellation in September, flight cancellation heatmap for each day in 2008 is shown in Figure 2. We can see that Sep. 12 to Sep. 14 have over 1000 flights cancellation each day and it is hurricane Ike after I check the weather history.

Figure 1: Flight Cancellation Rate of Each Month in 2008

How are cancellation categories defined

Extreme Weather: Significant meteorological conditions (actual or forecasted) that, in the judgment of the carrier, delays or prevents the operation of a flight such as tornado, blizzard or hurricane.

Air Carrier: The cause of the cancellation or delay was due to circumstances within the airline's control (e.g. maintenance or crew problems, aircraft cleaning, baggage loading, fueling, etc.).

National Aviation System (NAS): Delays and cancellations attributable to the national aviation system that refer to a broad set of conditions, such as non-extreme weather conditions, airport operations, heavy traffic volume, and air traffic control.

Security: Delays or cancellations caused by evacuation of a terminal or concourse, re-boarding of aircraft because of security breach, inoperative screening equipment and/or long lines in excess of 29 minutes at screening areas.

Figure 2: Number of Flight Cancellation for Each Day in 2008

Flight Delays

The average flight delay time is calculated over the hour of day as in Figure 3. The flights scheduled at 8 pm to 9 pm have the highest average delay time 17 minutes. The average delay time increases from 5 am to 8 pm. Then it decreases after 8 pm. At 3 am, the average delay time is 11 minutes which is significantly higher than other time in the early morning.

Figure 4 shows the average delay time over hours and days by week. Monday morning at 3 am have long delay time as well as Firday night 6 pm to 8 pm.