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Flight Reliability

DL 2521 · Delta Air Lines

This number covered several routes in this period.

One number, several routes.

Airlines reuse flight numbers, and DL 2521 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

82%
Arrive within 15 minutes
2 min
Average arrival delay
2.6%
Cancelled
9 min early
Median arrival delay

Based on 664 historical flights. Data through May 2026.

The breakdown

On-time by weekday
  • Mon87%(93 flights)
  • Tue90%(98 flights)
  • Wed88%(98 flights)
  • Thu81%(95 flights)
  • Fri80%(96 flights)
  • Sat69%(74 flights)
  • Sun79%(93 flights)
On-time by departure window
  • 6–9 AM80%(15 flights)
  • 9 AM–12 PM85%(188 flights)
  • 12–3 PM79%(198 flights)
  • 3–6 PM83%(242 flights)
  • 6–9 PM—(4 flights)
On-time trend by month
89%
May

Jun 81% → May 89% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202581%59
July 202569%62
August 202589%62
September 202577%60
October 2025100%56
November 202589%52
December 202583%24
January 202680%54
February 202680%51
March 202673%59
April 202682%56
May 202689%52
Departures on time
83%
Diverted
0%
Flights flown
647
Months covered
12

Keep nerding

Based on 664 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.