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Flight Reliability

DL 871 · Delta Air Lines

Salt Lake City → Seattle (SLC–SEA)

89
Pretty Reliable
WanderNerd Reliability Score
83%
Arrive within 15 minutes
0 min
Average arrival delay
0.6%
Cancelled
9 min early
Median arrival delay

Based on 332 historical flights. Data through May 2026.

What the data says

Friday is doing you no favors.

DL 871 arrived on time 90% of the time on Mondays and just 74% on Fridays. That gap is worth planning around.

A bit ahead of the SLC–SEA route.

DL 871 arrived on time 83% of the time, versus 80% across the SLC–SEA route.

Recent months have been rougher.

DL 871 arrived on time 79% of the time over the last three months in the data, compared with 88% in the three months before that.

The breakdown

On-time by weekday
  • Mon90%(51 flights)
  • Tue81%(47 flights)
  • Wed81%(47 flights)
  • Thu84%(51 flights)
  • Fri74%(50 flights)
  • Sat88%(34 flights)
  • Sun86%(50 flights)
On-time by departure window
  • 3–6 PM83%(326 flights)
  • 6–9 PM—(4 flights)
On-time trend by month
74%
May

Jun 87% → May 74% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202587%30
July 202587%31
August 202581%31
September 202590%30
October 202574%31
November 202583%23
December 202581%21
January 202696%26
February 202686%22
March 202677%26
April 202686%28
May 202674%31
Departures on time
81%
Diverted
0%
Flights flown
330
Months covered
12

Same route, other flights

Keep nerding

Based on 332 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.