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Flight Reliability

DL 1255 · Delta Air Lines

MDT → Atlanta (MDT–ATL)97% of its flights flew this route. The rest (LAS–ATL) are included in these numbers.

87
Pretty Reliable
WanderNerd Reliability Score
91%
Arrive within 15 minutes
7 min early
Average arrival delay
2.8%
Cancelled
16 min early
Median arrival delay

Based on 361 historical flights. Data through May 2026.

What the data says

The 6–9 AM departure wins.

DL 1255 departing between 6–9 AM arrived on time 91% of the time, versus 75% between 9 AM–12 PM.

Sunday scaries are real for this one.

DL 1255 arrived on time 94% of the time on Fridays. On Sundays: 82%.

A bit ahead of the MDT–ATL route.

DL 1255 arrived on time 91% of the time, versus 85% across the MDT–ATL route.

Better than the Delta Air Lines network average.

DL 1255 arrived on time 91% of the time, versus 81% across the Delta Air Lines network.

The breakdown

On-time by weekday
  • Mon92%(50 flights)
  • Tue88%(50 flights)
  • Wed94%(50 flights)
  • Thu90%(50 flights)
  • Fri94%(51 flights)
  • Sat94%(49 flights)
  • Sun82%(51 flights)
On-time by departure window
  • 6–9 AM91%(339 flights)
  • 9 AM–12 PM75%(12 flights)
On-time trend by month
97%
May

Jun 93% → May 97% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202593%29
July 202597%31
August 2025100%29
September 202593%30
October 202574%31
November 202590%30
December 202586%28
January 202689%28
February 202692%26
March 202684%31
April 202693%29
May 202697%29
Departures on time
94%
Diverted
0%
Flights flown
351
Months covered
12

Same route, other flights

Keep nerding

Based on 361 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.