Want to avoid flight delays? Decision Science News analyzed every single commercial flight in 2013 – 6 million of them — and came up with a rule of thumb: to avoid delays, don't fly between 11 am and 11 pm. And if that seems too onerous, at least definitely don't fly between 5 pm and 8 pm.
The average delay early in the morning is less than 10 minutes. By 7 pm, it's double that. The authors note that airlines add a bit of extra time into their projected arrival times, so a lot of flights are actually early — only about 40 percent had any delay at all. (Nondelayed flights were factored into the averages too.)
Of course, flying in the evenings after work is the most convenient time for a lot of people. So it's up to you whether the headache of a 20-minute delay is worth avoiding an early morning or late night at the airport.