Flight number record
OO 4135
SkyWest Airlines · Salt Lake City to Eugene
- Route
- SLC → EUG
- Departs
- 10:45
- Flights
- 365
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s OO 4135, 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 4135 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 14 points better than the national rate of 77.3%. When something does go wrong the average delay runs about an hour. That rests on 365 flights, with a median arrival 6 minutes early.
Set against the rest of the country, OO 4135's record is 14 points better than the US average of 77.3%. That gap is worth roughly 142 fewer late arrivals for every thousand flights.
Key figures
On time
91.5%
Arrivals under 15 minutes late, of 365 completed flights
Avg delay
58 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.89%
1 hour+ late
3.0%
National rate is 8.3%
These figures cover 365 flights between September 2025 and August 2026. The median arrival is 6 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 4135 flies
OO 4135 flies SLC to EUG without a single fixed slot. Its most common scheduled departure was 10:45, used on 254 of 365 flights, with 10:55 (59 flights) next.
- Departs 10:45254 flights69.6%
- Departs 10:5559 flights16.2%
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 4135 runs 8 points better at 91.5%. 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 4135 next to SLC to EUG
Every carrier on SLC to EUG combined arrived on time 90.9% of the time across 800 flights, so OO 4135 is about level with it. Across its whole network SkyWest Airlines managed 78.7%, which this flight beats by 13 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| OO 4135 | 365 | 91.5% | 58 min | 0.00% | A+ |
| All SkyWest Airlines on SLC–EUG | 800 | 90.9% | 54 min | 0.00% | A+ |
| All carriers on SLC–EUG | 800 | 90.9% | 54 min | 0.00% | A+ |
| SkyWest Airlines, whole network | 855,406 | 78.7% | 88 min | 1.79% | B |
Across the year
OO 4135 quarter by quarter
OO 4135 did not run the same all year. Its best quarter was Jul–Sep 2025 at 100.0% on time and its weakest Apr–Jun 2026 at 86.8%, a swing of 13 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 flights100.0%
- Oct–Dec 202592 flights94.6%
- Jan–Mar 202690 flights90.0%
- Apr–Jun 202691 flights86.8%
- Jul–Sep 202662 flights91.9%
Scale runs 80% to 100%.
By weekday, OO 4135 ranged from 86.5% on Wednesday to 96.2% on Tuesday. 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 4135 runs when it is late
Most of the lateness is short. 17 of the 31 late arrivals were under half an hour behind, and 11 reached an hour or more.
- 15+ min early90 flights24.7%
- Within 15 min244 flights66.8%
- 15–29 min late17 flights4.7%
- 30–59 min late3 flights0.8%
- 1–2 hours late7 flights1.9%
- 2+ hours late4 flights1.1%
Scale runs 0% to 100%.
Share of 365 completed flights by arrival against schedule.
8 of 29 late departures made up the time and arrived on time, 28% of them. 10 flights left on time and still arrived late.
The worst days
Worst days for OO 4135
The latest arrival of the period was on 26 March 2026, 4 hours 52 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). Three of the five worst days fell in May 2026.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 26 March 2026 | 4 hours 52 minutes | Carrier |
| 20 May 2026 | 2 hours 25 minutes | Carrier |
| 19 May 2026 | 2 hours 22 minutes | Carrier |
| 8 May 2026 | 2 hours 5 minutes | Carrier |
| 3 December 2025 | 1 hour 59 minutes | Carrier |
Delay causes
Why OO 4135 runs late
Carrier accounts for 90% of the 1,802 delay minutes carriers reported here, and the remaining four split what is left.
- 90%Carrier
- 5%National Airspace System
- 5%Extreme weather
The largest share of delay minutes, 90%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 1,614 of the 1,802 delay minutes reported here. The split is drawn from 1,802 delay minutes reported on OO 4135.
Cancellations are rare at 0.00%, below the national 1.89% and low enough to earn the plus on the grade. Almost no flights are 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 3.0% 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 618 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.
The same number turns up on one other city pair in the data, including EUG to SLC (248), but none flew often enough under OO 4135 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to SLC to EUG only.
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 4135
For a booking, OO 4135 has one of the better records a US domestic flight can show: 91.5% on time and 0.00% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- SLC to EUG, every carrier and departure
- EUG to SLC, the return direction
- SkyWest Airlines 3721 on the same route92.1%
- 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.