The Day After the Holiday

Summary

Thanksgiving Day was the easiest day: 93.2% of completed flights arrived on time against 80.8% on ordinary days of the same weekday, 12.4 points above the expected rate, and it beat expectation in 3 of 3 years. Dec 28 in the Christmas window was the hardest day: 66.2% of completed flights arrived on time against 78.0% expected, 11.8 points below it, and the day was below expectation in 3 of 3 years. Thanksgiving and Christmas each had a worst day below expectation in every year of the data.

The usual warning is about the day before a holiday. This report follows every day of the 5 holiday windows, 2,484,712 departures in all, and sets each one against ordinary days of the same weekday in the same season. That matters because a holiday falls on a different weekday from year to year, and because the ordinary pace differs from one season to the next. Each day’s expectation is worked out airport by airport, so a day is not blamed for the airports it happens to be busy at.

Points are the on-time arrival rate minus the expected rate, weighted by completed flights. A day before or after is any day in the holiday window other than the day itself. The worst day is the day furthest below its expected rate.

Thanksgiving Day, Christmas Day, Fourth of July, and Labor Day beat the expected on-time rate in every year of the data (4 of 5 holidays). Thanksgiving Day was the easiest day: 93.2% of completed flights arrived on time against 80.8% on ordinary days of the same weekday, 12.4 points above the expected rate, and it beat expectation in 3 of 3 years. The holiday itself was the best day of its window for 3 of 5 holidays. A year of Thanksgiving Day carried 9,337 departures at these airports, against 16,444 on each of the other days of its window.

Thanksgiving and Christmas each had a worst day (the Sunday after Thanksgiving and Dec 28 in the Christmas window) more than 3 standard errors below expectation in every year of the data. In each the worst day came after the holiday. Dec 28 in the Christmas window was the hardest day: 66.2% of completed flights arrived on time against 78.0% expected, 11.8 points below it, and the day was below expectation in 3 of 3 years. Of the 5 holidays, 4 had a lower average on-time rate against expectation in the days after the day itself than in the days before it (Thanksgiving, Christmas, Fourth of July, and Memorial Day).

Departures from the covered airports in the holiday window. Expected is the airports’ own rate on ordinary days of the same weekday within 28 days of the holiday, applied to each airport’s flights that day. Years below expected counts the years in which the day’s on-time rate was under expectation.

Departures from the covered airports in the holiday window. Expected is the airports’ own rate on ordinary days of the same weekday within 28 days of the holiday, applied to each airport’s flights that day. Years below expected counts the years in which the day’s on-time rate was under expectation.

The day with the largest excess of cancellations was the Saturday after Thanksgiving: 2.68% of scheduled departures cancelled against 0.73% expected. It was above expectation in 1 of 3 years. The on-time shortfalls above recur year after year; this cancellation excess does not, and a total over the years hides which year it came from.

The data holds 3 to 4 years of each holiday, a small number, and a holiday that fell in a storm in one of them leaves a mark on its average. The years-below column is there so a day that was bad once can be told from one that was bad every time. The expectation uses ordinary days within 28 days of the holiday, and an ordinary day that was itself a bad storm day lowers it. The comparison covers departures from covered airports and says nothing about how full the flights were.