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Flight Reliability

DL 400 · Delta Air Lines

San Francisco → Boston (SFO–BOS)

92
Nerd Approved
WanderNerd Reliability Score
91%
Arrive within 15 minutes
2 min early
Average arrival delay
1.4%
Cancelled
11 min early
Median arrival delay

Based on 364 historical flights. Data through May 2026.

What the data says

Friday has been the better bet.

A small edge: 94% on time on Fridays against 89% on Sundays.

Better than the SFO–BOS route average.

DL 400 arrived on time 91% of the time, versus 79% across the SFO–BOS route.

Better than the Delta Air Lines network average.

DL 400 arrived on time 91% of the time, versus 81% across the Delta Air Lines network.

The breakdown

On-time by weekday
  • Mon92%(50 flights)
  • Tue90%(51 flights)
  • Wed89%(52 flights)
  • Thu90%(50 flights)
  • Fri94%(52 flights)
  • Sat90%(51 flights)
  • Sun89%(52 flights)
On-time trend by month
94%
May

Jun 93% → May 94% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202593%30
July 202597%31
August 202594%31
September 202573%30
October 202572%29
November 202586%29
December 202597%31
January 202696%28
February 202689%27
March 2026100%31
April 202693%30
May 202694%31
Departures on time
94%
Diverted
0.3%
Flights flown
358
Months covered
12

Same route, other flights

Keep nerding

Based on 364 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.