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Flight Reliability

DL 663 · Delta Air Lines

Atlanta → Salt Lake City (ATL–SLC)

94
Nerd Approved
WanderNerd Reliability Score
88%
Arrive within 15 minutes
2 min early
Average arrival delay
0.5%
Cancelled
9 min early
Median arrival delay

Based on 365 historical flights. Data through May 2026.

What the data says

12–3 PM has a slight edge.

Departures between 12–3 PM arrived on time 91% of the time, against 88% between 9 AM–12 PM.

Saturday is the weak spot.

DL 663 arrived on time 94% of the time on Wednesdays. On Saturdays: 80%.

A bit ahead of the ATL–SLC route.

DL 663 arrived on time 88% of the time, versus 83% across the ATL–SLC route.

A bit ahead of the Delta Air Lines network.

DL 663 arrived on time 88% of the time, versus 81% across the Delta Air Lines network.

The breakdown

On-time by weekday
  • Mon85%(52 flights)
  • Tue90%(52 flights)
  • Wed94%(52 flights)
  • Thu92%(52 flights)
  • Fri92%(51 flights)
  • Sat80%(51 flights)
  • Sun83%(53 flights)
On-time by departure window
  • 9 AM–12 PM88%(340 flights)
  • 12–3 PM91%(23 flights)
On-time trend by month
94%
May

Jun 83% → May 94% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202583%30
July 202590%31
August 202580%30
September 2025100%30
October 202587%31
November 202597%30
December 202587%31
January 202680%30
February 202682%28
March 202687%31
April 202690%30
May 202694%31
Departures on time
85%
Diverted
0%
Flights flown
363
Months covered
12

Same route, other flights

Keep nerding

Based on 365 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.