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Flight Reliability

DL 521 · Delta Air Lines

Los Angeles → Dallas–Fort Worth (LAX–DFW)90% of its flights flew this route. The rest (DFW–LAX) are included in these numbers.

85
Pretty Reliable
WanderNerd Reliability Score
87%
Arrive within 15 minutes
1 min early
Average arrival delay
2.0%
Cancelled
8 min early
Median arrival delay

Based on 399 historical flights. Data through May 2026.

What the data says

Mornings have a slight edge.

Departures between 9 AM–12 PM arrived on time 90% of the time, against 84% between 3–6 PM.

Mondays have been rough.

DL 521 arrived on time 93% of the time on Tuesdays and just 78% on Mondays. That gap is worth planning around.

Better than the LAX–DFW route average.

DL 521 arrived on time 87% of the time, versus 75% across the LAX–DFW route.

A bit ahead of the Delta Air Lines network.

DL 521 arrived on time 87% of the time, versus 81% across the Delta Air Lines network.

The breakdown

On-time by weekday
  • Mon78%(55 flights)
  • Tue93%(59 flights)
  • Wed85%(58 flights)
  • Thu86%(55 flights)
  • Fri93%(59 flights)
  • Sat84%(50 flights)
  • Sun89%(53 flights)
On-time by departure window
  • 6–9 AM86%(236 flights)
  • 9 AM–12 PM90%(115 flights)
  • 3–6 PM84%(38 flights)
On-time trend by month
93%
May

Jun 77% → May 93% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202577%30
July 202584%31
August 202579%29
September 202590%30
October 202597%31
November 202582%27
December 202587%31
January 202687%30
February 202681%37
March 202689%47
April 202695%37
May 202693%29
Departures on time
88%
Diverted
0.5%
Flights flown
389
Months covered
12

Same route, other flights

Keep nerding

Based on 399 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.