In 2015, FiveThirtyEight, a data journalism website, analyzed over six million flights domestic flights in the United States. The goal of their analysis was to find the fastest airline on any particular route (i.e. Houston to Los Angeles) and determine the best-and-worst performing airlines and airports.

Under slightly different motivation, we built a logistic regression model tracking the probability that a flight is delayed by at least fifteen minutes using U.S. domestic flight data from the U.S. Department of Transportation in June 2016. The response (departure delay of fifteen minutes) is a binary variable taking on a 0 (not delayed fifteen minutes) or 1 outcome (delayed fifteen minutes). The predictor variables for this model are the day of the week, flight distance, airline carrier, and the origin airport.

The model is split into training and testing datasets as a measure for cross-validation. We found that the unique carrier (i.e. airline) and the flight distance were the most predictive variables in the model according to the variable importance feature that returns scaled results in the range of 0 to 100 (Figure 1 below).

According to Bloomberg, a business website, carrier delays exceeded weather delays and delays in the air traffic system for the first time in 2016. Carrier delays are most often caused by a late arriving aircraft (39.2%), a carrier delay such as a lack of flight crew (32.6%), or a national aviation system delay (23.7%). Another more recent element to flight delays are computer glitches that continue to ground thousands of passengers each year ranging giving airlines including Delta Airlines and United Airlines bad PR.

To a lesser degree, the origin airport and the day of the week also play a role in getting a fifteen-minute delay. Flights departing from Los Angeles (LAX) or New York City (LaGuardia) are far more prone to fifteen-minute delays than smaller market airports such as Cincinnati or San Diego.

In terms of departure flight delays, the worst days of the week to fly are on Monday (+15.5 minute delay) and Wednesday (+14.7). Fridays and Tuesdays were the best days to fly adding just 8.2 and 9.31 minutes respectively to the traveller’s takeoff delay.

Figure 1: Variable importance for the logistic regression model

Airline Performance

According to our model, Southwest (WN), American (AA), Delta (DL), and Hawaiian (HA) airlines had the highest probability of getting a fifteen-minute delay averaging a 21.73 percent probability for departing fights in June 2016. To be fair, not all fifteen-minute delays are the airline’s fault. Delays also stem from weather, security, or airport delays. On the other hand, the model was bullish on Virgin Airlines (VX) and SkyWest Airlines (OO) giving the two airlines an average 16.5 percent probability for a fifteen-minute departure delay.

Figure 2: The probability of a fifteen-minute delay for U.S. carriers (domestic flights)

In reality, however, the model is a little bit too much overconfident in Virgin’s performance. In June 2016, 23 percent of Virgin flights were delayed by at least fifteen minutes, which is only slightly better than Southwest (25.4%) and American Airlines (23.3%). Virgin’s main departure hubs are high-trafficked airports in San Francisco (SFO), Los Angeles (LAX), and New York City (JFK) that no doubt contribute to spikes in fifteen-minute delays.

Virgin is still a highly regarded airline even though it is overrated in our model. In 2016, it was named the top domestic airline in Travel and Leisure’s Best Awards Survey and by Conde Nast Traveller’s 2016 Readers Choice Awards for the ninth consecutive year. Other mainstream airlines like Delta (17.1%) and United Airlines (21.2%) were less likely to experience a fifteen-minute departure delay and were undervalued by the model.

Figure 3: The difference between the actual percentage of flights delayed by fifteen minutes and the probability of getting a fifteen-minute delay by the carrier

Hawaiian Airlines is the most undervalued carrier in our model performing 14.8 percent better than expected. Over 93 percent of Hawaiian Airline’s flights were delayed by 14 minutes or less outflanking all other carriers in June 2016.

The long flight distances from Hawaii to the U.S. played an insignificant role in slowing down Hawaiian Airlines’ takeoffs even though increasing the flight distance tends to correspond to more fifteen-minute delays (0.35 correlation between the average flight distance and fifteen-minute delays).

Figure 4: The average distance of departing flights and number of flights at U.S. domestic airports in June 2016

The majority of Hawaiian Airlines’ flights depart from relatively low traffic airports in Honolulu, Kahului, and Lihue that likely lowers the probability of a departure delay. Hawaiian Airlines primarily flies to cities populating the West Coast and New York City. In June 2016, 91.2 percent of flights flying out of Honolulu and 88.4 percent of flights departing from Kahului did not experience any fifteen-minute delays, which is among the best in the U.S.

In addition, over 86 and 82 percent of SkyWest and Delta’s flights left “on-time” outperforming their fifteen-minute flight delay probabilities (in the model) by an average of 4.3 percent. [1] On the flip side, Southwest Airlines’ departing flights left on time at just a 73.2 percent clip. In part, Southwest is handicapped by its frequent takeoff spots in Chicago, Las Vegas, and Baltimore that are prone to longer delays.

You Can’t Escape Departure Delays

Of cities with at least departing 1,500 flights in June 2016, passengers flying out of Baltimore had the highest probability (0.23) of a suffering a fifteen-minute departure delay according to the model. [2] In reality, 24.3 percent of Baltimore’s flights were delayed by at least fifteen minutes ranking seventh overall among qualified cities (minimum of 1,500 takeoffs) placing behind New York, Chicago, and Atlanta.

Figure 5: Percentage of flights delayed by fifteen minutes in cities with a minimum of 1,500 departing flights in June 2016

In terms of fifteen-minute delay frequency, the worst performing airports are Dallas and Dallas-Fort Worth alongside Los Angeles, Miami, and Newark. On the flip side, 83.6 and 82.2 percent of flights leaving from Minneapolis and Seattle, both mid-tier airports, did not experience any fifteen-minute delays.

Located 21.8 miles outside of downtown, Dallas-Fort Worth airport is Dallas’ central airport hub with 16671 departing flights in June 2016. Its smaller cousin, Dallas Love Field Airport, had just 5718 flight departures over the same time period.

To be fair, over 71 percent of all departing flights from Dallas-Forth Worth ran through American Airlines while 90.2 percent of departing flights from Dallas came via Southwest Airlines, which are two carriers both prone to delays. American Airlines (20.9%) and Southwest Airlines (18.8%) were also the most frequent takeoff flight providers from Los Angeles.

Boston’s top-flight provider is Jet Blue (B6), which was the second worst performing airline in June 2016 in terms of departure delays. However, only 18.4 percent of flights from Boston’s Logan Airport experienced fifteen-minute delays in June 2016 trailing only Minneapolis and Seattle among qualified cities. Passengers departing from Seattle benefited from flying with Alaska Airlines (40.7% of all departing flights in Seattle) and Delta (15.2%), two carriers that placed in the top-third for the lowest percentage of departing fifteen-minute delay flights among twelve U.S. carriers in this analysis.

Figure 6: The difference between the probability of a fifteen-minute delay and actual percentage of fifteen-minute delays among the largest U.S. flight hubs in June 2016

Among the largest U.S. flight markets, Minneapolis (-3.6%), Boston (-2.7%), and Seattle (-2.5%) performed the best against the model. In other words, the model predicted that these cities would experience a higher percentage of fifteen-minute departure delays. Meanwhile Los Angeles (+7.8%), Dallas/Fort Worth (6.6% and 7.6%), and Miami (+5.3%) posted a significantly higher percentage of fifteen-minute departure delays than predicted by the model.

Atlanta, the flight capital of the United States, performed more or less the same as expected. It is also worth noting that flights departing from Fort Lauderdale were delayed 2.9 percent less than in Miami despite increased departure traffic in Fort Lauderdale. Denver another major flight hub (tied for third in departure traffic with Los Angeles) also performed fairly well with just 21.4 percent delayed flights.

Obviously, this is only a small snapshot of airline and airport performances across the U.S. Departure delays will fluctuate depending on the time of the year and the weather. For example, flights taking off in Chicago during January will likely experience more delays than flights leaving in mid-July. This analysis, however, gives us a better idea of the best cities and airlines to fly with in the U.S.

Sources:

https://www.bloomberg.com/news/articles/2016-08-23/blame-the-airlines-not-the-weather-for-most-u-s-flight-delays

https://fivethirtyeight.com/features/how-we-found-the-fastest-flights/

[1] Did not experience a fifteen-minute departure delay

[2] 8,583 flights departed from Baltimore in June 2016.

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