Flight number record
OO 4138
SkyWest Airlines · Fresno to Salt Lake City
- Route
- FAT → SLC
- Departs
- 06:00
- Flights
- 365
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s OO 4138, 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 4138 earns an A+. Nearly every flight arrives inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 19 points better than the national rate of 77.3%. When something does go wrong the average delay runs about 2.9 hours. That rests on 365 flights, with a median arrival 17 minutes early.
Set against the rest of the country, OO 4138's record is 19 points better than the US average of 77.3%. That gap is worth roughly 186 fewer late arrivals for every thousand flights.
Key figures
On time
95.9%
Arrivals under 15 minutes late, of 362 completed flights
Avg delay
171 min
Across delayed arrivals only, not all flights
Cancelled
0.55%
National rate is 1.89%
1 hour+ late
2.5%
National rate is 8.3%
These figures cover 365 flights between September 2025 and August 2026. The median arrival is 17 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 4138 flies
OO 4138 flies FAT to SLC without a single fixed slot. Its most common scheduled departure was 06:00, used on 144 of 365 flights, with 06:05 (72 flights) and 06:10 (55 flights) next.
- Departs 06:00144 flights39.5%
- Departs 06:0572 flights19.7%
- Departs 06:1055 flights15.1%
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 OO 4138 runs 7 points better at 95.9%. 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 4138 next to FAT to SLC
Every carrier on FAT to SLC combined arrived on time 93.3% of the time across 1,365 flights, so OO 4138 is 3 points ahead of it. Across its whole network SkyWest Airlines managed 78.7%, which this flight beats by 17 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| OO 4138 | 365 | 95.9% | 171 min | 0.55% | A+ |
| All SkyWest Airlines on FAT–SLC | 1,365 | 93.3% | 84 min | 0.51% | A+ |
| All carriers on FAT–SLC | 1,365 | 93.3% | 84 min | 0.51% | A+ |
| SkyWest Airlines, whole network | 855,406 | 78.7% | 88 min | 1.79% | B |
Across the year
OO 4138 quarter by quarter
Quarter by quarter OO 4138 held fairly steady: 96.7% in Jul–Sep 2025, 95.7% in Oct–Dec 2025, 94.3% in Jan–Mar 2026, 97.8% in Apr–Jun 2026 and 95.1% in Jul–Sep 2026. A spread of 4 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 202592 flights95.7%
- Jan–Mar 202690 flights94.3%
- Apr–Jun 202691 flights97.8%
- Jul–Sep 202662 flights95.1%
Scale runs 85% to 100%.
By weekday, OO 4138 ranged from 92.2% on Sunday to 100.0% on Wednesday. With about 52 flights behind each day, a spread of 8 points is inside normal variation, so the day you fly is not worth changing for this flight.
Arrival by arrival
How late OO 4138 runs when it is late
OO 4138 often beats the schedule: 225 of 362 completed flights, 62%, arrived 15 minutes or more early. When OO 4138 is late it tends to be very late: 9 of its 15 late arrivals were an hour or more behind, and 7 were two hours or more.
- 15+ min early225 flights62.2%
- Within 15 min122 flights33.7%
- 15–29 min late4 flights1.1%
- 30–59 min late2 flights0.6%
- 1–2 hours late2 flights0.6%
- 2+ hours late7 flights1.9%
Scale runs 0% to 100%.
Share of 362 completed flights by arrival against schedule.
Only 15 of 362 completed flights left 15 minutes late or more, too few to say how often the time is made up.
The worst days
Worst days for OO 4138
The latest arrival of the period was on 8 May 2026, 9 hours 29 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 |
|---|---|---|
| 8 May 2026 | 9 hours 29 minutes | Carrier |
| 16 January 2026 | 7 hours 39 minutes | Extreme weather |
| 23 August 2026 | 6 hours 21 minutes | Carrier |
| 17 November 2025 | 4 hours 53 minutes | Carrier |
| 25 January 2026 | 2 hours 53 minutes | Carrier |
Delay causes
Why OO 4138 runs late
Carrier accounts for 81% of the 2,565 delay minutes carriers reported here, and the remaining four split what is left.
- 81%Carrier
- 18%Extreme weather
- 1%National Airspace System
Extreme weather accounts for 18% 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 3.0 times the usual weather exposure. The split is drawn from 2,565 delay minutes reported on OO 4138.
Cancellations are rare at 0.55%, 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 2.5% 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.
The 501 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.
Every one of the 365 flights under OO 4138 in the data flew FAT to SLC. 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. 365 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 OO 4138
For a booking, OO 4138 has one of the better records a US domestic flight can show: 95.9% on time and 0.55% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- FAT to SLC, every carrier and departure
- SLC to FAT, the return direction
- SkyWest Airlines 3768 on the same route92.6%
- SkyWest Airlines 3777 on the same route89.5%
- SkyWest Airlines 3786 on the same route96.2%
- 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
- Late aircraft, weather, or the airline: what actually causes US flight delays
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.