Flight number record
DL 1597
Delta Air Lines · St. Louis to Minneapolis
- Route
- STL → MSP
- Departs
- 06:00
- Flights
- 364
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s DL 1597, check with Delta Air Lines.
DL 1597 earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 13 points better than the national rate of 77.3%. When something does go wrong the average delay runs an hour and a half. That rests on 364 flights, with a median arrival 13 minutes early.
Set against the rest of the country, DL 1597's record is 13 points better than the US average of 77.3%. That gap is worth roughly 133 fewer late arrivals for every thousand flights.
Key figures
On time
90.6%
Arrivals under 15 minutes late, of 361 completed flights
Avg delay
91 min
Across delayed arrivals only, not all flights
Cancelled
0.82%
National rate is 1.89%
1 hour+ late
3.3%
National rate is 8.3%
These figures cover 364 flights between September 2025 and August 2026. The median arrival is 13 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
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Schedule
When DL 1597 flies
DL 1597 flies STL to MSP without a single fixed slot. Its most common scheduled departure was 06:00, used on 110 of 364 flights, with 06:21 (88 flights) and 06:10 (62 flights) next.
- Departs 06:00110 flights30.2%
- Departs 06:2188 flights24.2%
- Departs 06:1062 flights17.0%
Scale runs 0% to 100%.
Share of scheduled departures at each local time. Times used on fewer than one flight in ten are not listed.
A 06:00 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and DL 1597 runs level with that at 90.6%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
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Against the route
DL 1597 next to STL to MSP
Every carrier on STL to MSP combined arrived on time 79.4% of the time across 1,962 flights, so DL 1597 is 11 points ahead of it. Delta flew 906 flights on the same city pair under all its flight numbers, including this one, and those ran 85.0% on time. Across its whole network Delta Air Lines managed 81.1%, which this flight beats by 10 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DL 1597thin sample | 364 | 90.6% | 91 min | 0.82% | A+ |
| All Delta Air Lines on STL–MSP | 906 | 85.0% | 86 min | 1.10% | A |
| All carriers on STL–MSP | 1,962 | 79.4% | 75 min | 0.92% | B+ |
| Delta Air Lines, whole network | 1,039,517 | 81.1% | 71 min | 1.74% | B |
Across the year
DL 1597 quarter by quarter
DL 1597 did not run the same all year. Its best quarter was Jul–Sep 2025 at 96.7% on time and its weakest Oct–Dec 2025 at 85.9%, a swing of 11 points on roughly 73 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.
- Jul–Sep 202530 flights96.7%
- Oct–Dec 202592 flights85.9%
- Jan–Mar 202690 flights93.2%
- Apr–Jun 202691 flights92.2%
- Jul–Sep 202661 flights88.5%
Scale runs 75% to 100%.
By weekday, DL 1597 ranged from 86.5% on Tuesday to 92.3% on Wednesday. With about 52 flights behind each day, a spread of 6 points is inside normal variation, so the day you fly is not worth changing for this flight.
Arrival by arrival
How late DL 1597 runs when it is late
DL 1597 often beats the schedule: 156 of 361 completed flights, 43%, arrived 15 minutes or more early. The 34 late arrivals split 15 under half an hour, 7 between 30 and 60 minutes, and 12 an hour or more.
- 15+ min early156 flights43.2%
- Within 15 min171 flights47.4%
- 15–29 min late15 flights4.2%
- 30–59 min late7 flights1.9%
- 1–2 hours late4 flights1.1%
- 2+ hours late8 flights2.2%
Scale runs 0% to 100%.
Share of 361 completed flights by arrival against schedule.
Time lost at the gate mostly stays lost. Of 27 departures that left 15 minutes late or more, only 2 made it up before arrival. 9 flights left on time and still arrived late.
The worst days
Worst days for DL 1597
The latest arrival of the period was on 30 September 2025, 7 hours 53 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on four of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 30 September 2025 | 7 hours 53 minutes | Carrier |
| 24 October 2025 | 6 hours 52 minutes | Late-arriving aircraft |
| 30 November 2025 | 5 hours 31 minutes | Carrier |
| 14 October 2025 | 4 hours 36 minutes | Carrier |
| 24 December 2025 | 2 hours 53 minutes | Carrier |
Delay causes
Why DL 1597 runs late
Carrier accounts for 75% of the 3,091 delay minutes carriers reported here, and the remaining four split what is left.
- 75%Carrier
- 13%Late-arriving aircraft
- 8%National Airspace System
- 5%Extreme weather
The largest share of delay minutes, 75%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 2,303 of the 3,091 delay minutes reported here. The split is drawn from 3,091 delay minutes reported on DL 1597.
Cancellations are rare at 0.82%, below the national 1.89% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and routes
What a delay on this flight costs
Badly late arrivals are rare here: only 3.3% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
Every one of the 364 flights under DL 1597 in the data flew STL to MSP. The number was not reused on any other city pair, which makes this a clean record of one route.
One caution: this is a thin sample. 364 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking DL 1597
For a booking, DL 1597 has one of the better records a US domestic flight can show: 90.6% on time and 0.82% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- STL to MSP, every carrier and departure
- MSP to STL, the return direction
- St. Louis Lambert International (STL) delay statistics
- Minneapolis-St Paul International (MSP) delay statistics
- Delta Air Lines on-time record
- Every Delta Air Lines flight number with a record
- The most and least reliable flight numbers in the US
- Worst months to fly in the US, ranked by the data
A flight number here means Delta Air Lines’s own number as it reports to the DOT. How the figures are computed is on the methodology page.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.