Flight number record
OO 4640
SkyWest Airlines · Huntsville to Denver
- Route
- HSV → DEN
- Departs
- 08:00
- Flights
- 365
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 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 10 points better than the national rate of 77.6%. 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 10 points better than the US average of 77.6%. That gap is worth roughly 103 fewer late arrivals for every thousand flights.
Key figures
On time
87.9%
Arrivals under 15 minutes late, of 365 completed flights
Avg delay
76 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.81%
1 hour+ late
3.6%
National rate is 8.1%
These figures cover 365 flights between July 2025 and June 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.
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 154 of 365 flights, with 08:09 (65 flights) and 08:13 (37 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 08:00154 flights42.2%
- Departs 08:0965 flights17.8%
- Departs 08:1337 flights10.1%
Scale runs 0% to 100%. Rows with fewer than 30 flights show a dash.
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 84.1%, and OO 4640 runs 4 points better at 87.9%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.
Against the route
OO 4640 next to HSV to DEN
Every carrier on HSV to DEN combined arrived on time 83.7% of the time across 729 flights, so OO 4640 is 4 points ahead of it. Across its whole network SkyWest Airlines managed 79.0%, which this flight beats by 9 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| OO 4640 | 365 | 87.9% | 76 min | 0.00% | A+ |
| All SkyWest Airlines on HSV–DEN | 729 | 83.7% | 75 min | 0.00% | B+ |
| All carriers on HSV–DEN | 729 | 83.7% | 75 min | 0.00% | B+ |
| SkyWest Airlines, whole network | 852,935 | 79.0% | 88 min | 1.77% | B |
Across the year
OO 4640 quarter by quarter
Quarter by quarter OO 4640 held fairly steady: 85.9% in Jul–Sep 2025, 88.0% in Oct–Dec 2025, 84.4% in Jan–Mar 2026 and 93.4% in Apr–Jun 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 202592 flights85.9%
- Oct–Dec 202592 flights88.0%
- Jan–Mar 202690 flights84.4%
- Apr–Jun 202691 flights93.4%
Scale runs 75% to 100%. Rows with fewer than 30 flights show a dash.
By weekday, OO 4640 ranged from 82.7% on Thursday to 94.2% on Saturday. With about 52 flights behind each day, a spread of 12 points is inside normal variation, so the day you fly is not worth changing for this flight.
Delay causes
Why OO 4640 runs late
One category carries most of the weight here. Carrier accounts for 73% of the 3,325 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 73%Carrier
- 24%National Airspace System
- 2%Late-arriving aircraft
- 1%Extreme weather
The largest share of delay minutes, 73%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 2,423 of the 3,325 delay minutes reported here. The split is drawn from 3,325 delay minutes reported on OO 4640.
Cancellations are rare at 0.00%, below the national 1.81% 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 3.6% land an hour or more behind schedule, against 8.1% 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. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.
The same number turns up on one other city pair in the data, including DEN to GUC (73), 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: 87.9% 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 route79.5%
- 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.