Flight number record
OO 3859
SkyWest Airlines · Salt Lake City to Great Falls
- Route
- SLC → GTF
- Departs
- 10:45
- Flights
- 364
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s OO 3859, check with SkyWest Airlines. SkyWest Airlines flies under contract for larger airlines, so a ticket for this flight may show a different airline code and number.
OO 3859 earns an A. Nearly every flight arrives inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 18 points better than the national rate of 77.3%. When something does go wrong the average delay runs about an hour. That rests on 364 flights, with a median arrival 9 minutes early.
Set against the rest of the country, OO 3859's record is 18 points better than the US average of 77.3%. That gap is worth roughly 177 fewer late arrivals for every thousand flights.
Key figures
On time
95.0%
Arrivals under 15 minutes late, of 359 completed flights
Avg delay
66 min
Across delayed arrivals only, not all flights
Cancelled
1.37%
National rate is 1.89%
1 hour+ late
1.1%
National rate is 8.3%
These figures cover 364 flights between September 2025 and August 2026. The median arrival is 9 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 OO 3859 flies
OO 3859 flies SLC to GTF without a single fixed slot. Its most common scheduled departure was 10:45, used on 266 of 364 flights, with 10:55 (57 flights) next.
- Departs 10:45266 flights73.1%
- Departs 10:5557 flights15.7%
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 10:45 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 83.9%, and OO 3859 runs 11 points better at 95.0%. 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
OO 3859 next to SLC to GTF
Every carrier on SLC to GTF combined arrived on time 93.4% of the time across 1,072 flights, so OO 3859 is 2 points ahead of it. Across its whole network SkyWest Airlines managed 78.7%, which this flight beats by 16 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| OO 3859thin sample | 364 | 95.0% | 66 min | 1.37% | A |
| All SkyWest Airlines on SLC–GTF | 1,072 | 93.4% | 52 min | 0.75% | A+ |
| All carriers on SLC–GTF | 1,072 | 93.4% | 52 min | 0.75% | A+ |
| SkyWest Airlines, whole network | 855,406 | 78.7% | 88 min | 1.79% | B |
Across the year
OO 3859 quarter by quarter
Quarter by quarter OO 3859 held fairly steady: 96.7% in Jul–Sep 2025, 98.9% in Oct–Dec 2025, 92.1% in Jan–Mar 2026, 96.7% in Apr–Jun 2026 and 90.3% in Jul–Sep 2026. A spread of 9 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.
- Jul–Sep 202530 flights96.7%
- Oct–Dec 202591 flights98.9%
- Jan–Mar 202690 flights92.1%
- Apr–Jun 202691 flights96.7%
- Jul–Sep 202662 flights90.3%
Scale runs 80% to 100%.
By weekday, OO 3859 ranged from 90.0% on Thursday to 100.0% on Wednesday. With about 52 flights behind each day, a spread of 10 points is inside normal variation, so the day you fly is not worth changing for this flight.
Arrival by arrival
How late OO 3859 runs when it is late
OO 3859 often beats the schedule: 120 of 359 completed flights, 33%, arrived 15 minutes or more early. The 18 late arrivals split 4 under half an hour, 10 between 30 and 60 minutes, and 4 an hour or more.
- 15+ min early120 flights33.4%
- Within 15 min221 flights61.6%
- 15–29 min late4 flights1.1%
- 30–59 min late10 flights2.8%
- 1–2 hours late1 flights0.3%
- 2+ hours late3 flights0.8%
Scale runs 0% to 100%.
Share of 359 completed flights by arrival against schedule.
A late pushback is often recovered here: of 22 departures that left 15 minutes late or more, 8 still arrived on time. Only 4 left on time and still arrived late.
The worst days
Worst days for OO 3859
The latest arrival of the period was on 12 March 2026, 3 hours 12 minutes behind schedule; most of its delay minutes were filed as extreme weather. On four of the five worst days the largest share was filed as carrier-caused (crew, maintenance, fuelling, baggage).
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 12 March 2026 | 3 hours 12 minutes | Extreme weather |
| 2 August 2026 | 2 hours 59 minutes | Carrier |
| 2 February 2026 | 2 hours 54 minutes | Carrier |
| 13 February 2026 | 1 hour 56 minutes | Carrier |
| 25 June 2026 | 59 minutes | Carrier |
Delay causes
Why OO 3859 runs late
Carrier accounts for 75% of the 1,186 delay minutes carriers reported here, and the remaining four split what is left.
- 75%Carrier
- 22%Extreme weather
- 2%National Airspace System
Extreme weather accounts for 22% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the quarterly figures above are the more useful view of the risk. The national share is 6%, so this operation carries roughly 3.7 times the usual weather exposure. The split is drawn from 1,186 delay minutes reported on OO 3859.
Cancellations sit at 1.37% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and routes
What a delay on this flight costs
Badly late arrivals are rare here: only 1.1% 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.
OO 3859 is not only a SLC to GTF flight. It also flew GTF to SLC (364 flights, 91.9% on time) often enough to be scored on its own. Airlines attach one number to several legs of an aircraft's day, and each leg keeps its own record here, so check which city pair is on your booking before reading a rate.
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.
| Also flown as | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| GTF to SLCthin sample | 364 | 91.9% | 47 min | 1.37% | A |
What to do with this
Booking OO 3859
For a booking, OO 3859 has one of the better records a US domestic flight can show: 95.0% on time and 1.37% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- SLC to GTF, every carrier and departure
- GTF to SLC, the return direction
- SkyWest Airlines 3845 on the same route95.9%
- SkyWest Airlines 3800 on the same route89.1%
- Salt Lake City International (SLC) delay statistics
- SkyWest Airlines on-time record
- Every SkyWest Airlines 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 SkyWest Airlines’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.