Flight number record
OO 4127
SkyWest Airlines · Seattle to Boise
- Route
- SEA → BOI
- Departs
- 10:40
- Flights
- 365
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s OO 4127, 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 4127 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 10 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 4127's record is 10 points better than the US average of 77.3%. That gap is worth roughly 101 fewer late arrivals for every thousand flights.
Key figures
On time
87.4%
Arrivals under 15 minutes late, of 364 completed flights
Avg delay
61 min
Across delayed arrivals only, not all flights
Cancelled
0.27%
National rate is 1.89%
1 hour+ late
4.1%
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 4127 flies
OO 4127 flies SEA to BOI without a single fixed slot. Its most common scheduled departure was 10:40, used on 83 of 365 flights, with 10:35 (77 flights) next.
- Departs 10:4083 flights22.7%
- Departs 10:3577 flights21.1%
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 10:40 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 83.9%, and OO 4127 runs 4 points better at 87.4%. 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 4127 next to SEA to BOI
Every carrier on SEA to BOI combined arrived on time 86.3% of the time across 3,829 flights, so OO 4127 is about level with it. SkyWest flew 2,853 flights on the same city pair under all its flight numbers, including this one, and those ran 87.8% on time. Across its whole network SkyWest Airlines managed 78.7%, which this flight beats by 9 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| OO 4127 | 365 | 87.4% | 61 min | 0.27% | A+ |
| All SkyWest Airlines on SEA–BOI | 2,853 | 87.8% | 55 min | 0.21% | A+ |
| All carriers on SEA–BOI | 3,829 | 86.3% | 51 min | 0.26% | A+ |
| SkyWest Airlines, whole network | 855,406 | 78.7% | 88 min | 1.79% | B |
Across the year
OO 4127 quarter by quarter
Quarter by quarter OO 4127 held fairly steady: 90.0% in Jul–Sep 2025, 91.2% in Oct–Dec 2025, 83.3% in Jan–Mar 2026, 90.1% in Apr–Jun 2026 and 82.3% 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 flights90.0%
- Oct–Dec 202592 flights91.2%
- Jan–Mar 202690 flights83.3%
- Apr–Jun 202691 flights90.1%
- Jul–Sep 202662 flights82.3%
Scale runs 75% to 95%.
By weekday, OO 4127 did best on Saturday at 98.0% on time and worst on Monday at 81.1%. Each day rests on about 52 flights, so a gap of 17 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late OO 4127 runs when it is late
The 46 late arrivals split 20 under half an hour, 11 between 30 and 60 minutes, and 15 an hour or more.
- 15+ min early80 flights22.0%
- Within 15 min238 flights65.4%
- 15–29 min late20 flights5.5%
- 30–59 min late11 flights3.0%
- 1–2 hours late8 flights2.2%
- 2+ hours late7 flights1.9%
Scale runs 0% to 100%.
Share of 364 completed flights by arrival against schedule.
8 of 40 late departures made up the time and arrived on time, 20% of them. 14 flights left on time and still arrived late.
The worst days
Worst days for OO 4127
The latest arrival of the period was on 13 March 2026, 5 hours 7 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 |
|---|---|---|
| 13 March 2026 | 5 hours 7 minutes | Extreme weather |
| 15 March 2026 | 3 hours 57 minutes | Carrier |
| 30 July 2026 | 2 hours 42 minutes | Carrier |
| 14 May 2026 | 2 hours 30 minutes | Carrier |
| 16 July 2026 | 2 hours 5 minutes | Carrier |
Delay causes
Why OO 4127 runs late
Carrier accounts for 60% of the 2,815 delay minutes carriers reported here, and the remaining four split what is left.
- 60%Carrier
- 23%Extreme weather
- 17%National Airspace System
Extreme weather accounts for 23% 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 3.8 times the usual weather exposure. The split is drawn from 2,815 delay minutes reported on OO 4127.
Cancellations are rare at 0.27%, 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 4.1% 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 4127 is not only a SEA to BOI flight. It also flew BOI to SEA (333 flights, 82.8% 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. 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.
| Also flown as | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| BOI to SEAthin sample | 333 | 82.8% | 56 min | 0.60% | B+ |
What to do with this
Booking OO 4127
For a booking, OO 4127 has one of the better records a US domestic flight can show: 87.4% on time and 0.27% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- SEA to BOI, every carrier and departure
- BOI to SEA, the return direction
- SkyWest Airlines 3688 on the same route85.8%
- SkyWest Airlines 3692 on the same route86.1%
- SkyWest Airlines 3750 on the same route92.9%
- Seattle-Tacoma International (SEA) 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
- The best time of day to fly, according to 7.05 million flight records
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.