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Flight Reliability

DL 509 · Delta Air Lines

This number covered several routes in this period.

One number, several routes.

Airlines reuse flight numbers, and DL 509 moved between routes during this period. Numbers below combine all of them, so treat them as background, not a verdict. For a cleaner answer, check the route you are actually flying.

Combined across all its routes

75%
Arrive within 15 minutes
24 min
Average arrival delay
0.6%
Cancelled
3 min early
Median arrival delay

Based on 316 historical flights. Data through May 2026.

The breakdown

On-time by weekday
  • Mon67%(52 flights)
  • Tue77%(47 flights)
  • Wed78%(45 flights)
  • Thu80%(49 flights)
  • Fri84%(49 flights)
  • Sat64%(22 flights)
  • Sun68%(50 flights)
On-time by departure window
  • 3–6 PM—(5 flights)
  • 6–9 PM74%(285 flights)
  • 9 PM–12 AM83%(24 flights)
On-time trend by month
77%
May

Jun 82% → May 77% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202582%27
July 202559%22
August 202576%25
September 202585%26
October 202592%26
November 202587%23
December 202568%25
January 202663%30
February 202675%28
March 202664%28
April 202668%28
May 202677%26
Departures on time
70%
Diverted
0%
Flights flown
314
Months covered
12

Keep nerding

Based on 316 historical flights, because apparently we checked. Historical flight data: U.S. Bureau of Transportation Statistics, June 2025 – May 2026. Data through May 2026. How we calculate this.