Flight number record
OO 4640
SkyWest Airlines · Huntsville to Denver
- Route
- HSV → DEN
- Departs
- 08:00
- Flights
- 365
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s OO 4640, 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 4640 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 12 points better than the national rate of 77.3%. When something does go wrong the average delay runs a little over an hour. That rests on 365 flights, with a median arrival 11 minutes early.
Set against the rest of the country, OO 4640's record is 12 points better than the US average of 77.3%. That gap is worth roughly 120 fewer late arrivals for every thousand flights.
Key figures
On time
89.3%
Arrivals under 15 minutes late, of 365 completed flights
Avg delay
74 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.89%
1 hour+ late
3.8%
National rate is 8.3%
These figures cover 365 flights between September 2025 and August 2026. The median arrival is 11 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 4640 flies
OO 4640 flies HSV to DEN without a single fixed slot. Its most common scheduled departure was 08:00, used on 216 of 365 flights, with 07:45 (37 flights) next.
- Departs 08:00216 flights59.2%
- Departs 07:4537 flights10.1%
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 08:00 departure sits in the 8am–11am window. Across every US flight scheduled in that window the on-time rate is 83.9%, and OO 4640 runs 5 points better at 89.3%. 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 4640 next to HSV to DEN
Every carrier on HSV to DEN combined arrived on time 85.2% of the time across 728 flights, so OO 4640 is 4 points ahead of it. Across its whole network SkyWest Airlines managed 78.7%, which this flight beats by 11 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| OO 4640 | 365 | 89.3% | 74 min | 0.00% | A+ |
| All SkyWest Airlines on HSV–DEN | 728 | 85.2% | 73 min | 0.27% | A+ |
| All carriers on HSV–DEN | 728 | 85.2% | 73 min | 0.27% | A+ |
| SkyWest Airlines, whole network | 855,406 | 78.7% | 88 min | 1.79% | B |
Across the year
OO 4640 quarter by quarter
Quarter by quarter OO 4640 held fairly steady: 90.0% in Jul–Sep 2025, 88.0% in Oct–Dec 2025, 84.4% in Jan–Mar 2026, 93.4% in Apr–Jun 2026 and 91.9% 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 flights88.0%
- Jan–Mar 202690 flights84.4%
- Apr–Jun 202691 flights93.4%
- Jul–Sep 202662 flights91.9%
Scale runs 75% to 100%.
By weekday, OO 4640 did best on Saturday at 96.2% on time and worst on Tuesday at 82.7%. Each day rests on about 52 flights, so a gap of 14 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late OO 4640 runs when it is late
OO 4640 often beats the schedule: 154 of 365 completed flights, 42%, arrived 15 minutes or more early. The 39 late arrivals split 14 under half an hour, 11 between 30 and 60 minutes, and 14 an hour or more.
- 15+ min early154 flights42.2%
- Within 15 min172 flights47.1%
- 15–29 min late14 flights3.8%
- 30–59 min late11 flights3.0%
- 1–2 hours late6 flights1.6%
- 2+ hours late8 flights2.2%
Scale runs 0% to 100%.
Share of 365 completed flights by arrival against schedule.
A late pushback is often recovered here: of 44 departures that left 15 minutes late or more, 14 still arrived on time. 9 flights left on time and still arrived late.
The worst days
Worst days for OO 4640
The latest arrival of the period was on 24 April 2026, 9 hours 36 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 24 April 2026 | 9 hours 36 minutes | Carrier |
| 5 June 2026 | 3 hours 30 minutes | Carrier |
| 9 July 2026 | 3 hours 12 minutes | Late-arriving aircraft |
| 28 July 2026 | 2 hours 44 minutes | Carrier |
| 17 February 2026 | 2 hours 41 minutes | National Airspace System |
Delay causes
Why OO 4640 runs late
Carrier accounts for 82% of the 2,887 delay minutes carriers reported here, and the remaining four split what is left.
- 82%Carrier
- 12%National Airspace System
- 7%Late-arriving aircraft
The largest share of delay minutes, 82%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 2,360 of the 2,887 delay minutes reported here. The split is drawn from 2,887 delay minutes reported on OO 4640.
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 3.8% 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 1,048 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 DEN to GUC (135), but none flew often enough under OO 4640 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to HSV to DEN 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 4640
For a booking, OO 4640 has one of the better records a US domestic flight can show: 89.3% on time and 0.00% cancelled. That is a base rate, not a promise about any single day.
Related
Where to go next
- HSV to DEN, every carrier and departure
- DEN to HSV, the return direction
- SkyWest Airlines 5393 on the same route81.1%
- Denver International (DEN) 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.