Flight profile · SkyWest Airlines
OO5555
Chicago (ORD) to Milwaukee (MKE) · scheduled 5:50 PM – 7:10 PM
How OO5555 performs
1,003 operations, October 2023 – July 2026.
OO5555 arrived on time 62.2% of the time, against 68.6% for all ORD → MKE flights, so this departure is 6.4 percentage points worse than the route as a whole. Against SkyWest Airlines’ own flights on this route it is 5.9 points worse.
OO5555’s scheduled departure has moved during the period FlyerIntel has on file: it typically left around 6:15 PM earlier on, and around 5:45 PM more recently — a 30-minute shift, not the few minutes of day-to-day rounding every published schedule carries. Confirm the current departure time before booking around an older listing.
Source: US DOT Bureau of Transportation Statistics · 1,003 operations, October 2023 – July 2026 · If OO5555 is cancelled or significantly changed, DOT’s automatic refund rule may entitle you to your money back. The refund checker walks through eligibility.
What stands out
How OO5555 compares to other flight numbers, not just to itself.
This flight's worst arrivals run unusually far past its typical one, a bigger gap than 92% of 11,788 comparable flight numbers.
A typical arrival is 3 min late, but the worst tenth run 96 minutes worse than that.
Source: FlyerIntel analysis of US DOT BTS data · October 2023 – July 2026 · The one thing about this specific departure that ranks most extreme against every other published flight number, out of everything FlyerIntel checks — shown only when something clears a real statistical bar, not for every flight.
Where OO5555 is right now
A live reading, only if you ask for it. It is not part of the reliability record above.
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Against the rest of the route
| Flight or route | On time | Cancelled | Median delay | Severe | Flights |
|---|---|---|---|---|---|
| OO5555 | 62.2% | 2.49% | 3 min | 16.7% | 1,003 |
| SkyWest Airlines on ORD → MKE | 68.1% | 2.91% | -1 min | 14.3% | 10,532 |
| All ORD → MKE flights | 68.6% | 2.97% | -1 min | 14.0% | 11,099 |
Source: FlyerIntel analysis of US DOT BTS data · October 2023 – July 2026
Why OO5555 runs late
Where US DOT attributed the delay minutes on this flight.
crew, maintenance, boarding and fueling, all within the carrier’s control
the inbound aircraft was late, so this flight started late
airspace and airport capacity, including weather-driven flow control
weather severe enough to stop this flight specifically
Share of the delay minutes US DOT attributed to each cause for OO5555 on ORD → MKE. Only delays of 15 minutes or more are attributed.
Source: US DOT Bureau of Transportation Statistics · Data covering October 2023 – July 2026
Does a late aircraft delay this flight?
How often the plane that flies OO5555 comes in late, and what that does to the departure.
When the aircraft came in 15 or more minutes late, OO5555 pushed back an average of 56 minutes late; when it came in on time or early, an average of 6 minutes late.
Each departure is matched to the flight the same aircraft flew into ORD just before it, using the tail number in the DOT file, 914 of 978 departures in all. A departure is left out when that flight is unknown, was cancelled or diverted, or the aircraft had sat for more than 12 hours. A flight the airline cancelled never left and is not in the count, and one flown by a substitute aircraft is matched to the aircraft that flew it, not to the one first planned.
Against the network at the same turn length
| Share of departures | Inbound landed 15+ late | Left 15+ late after a late inbound | Left 15+ late after an on-time inbound |
|---|---|---|---|
| OO5555 | 32% | 57% | 13% |
| Network, same turn | 17% | 68% | 9% |
The schedule leaves a normal turn: enough time to clean and board if the aircraft is on time, little to spare if it is not.
The network row is every flight with a scheduled turn of 60 to 89 minutes. How often OO5555’s aircraft landed 15 or more minutes late is higher than the network’s and, once the aircraft was late, how often OO5555 left 15 or more minutes late is lower than the network’s.
More: Which Flight Numbers Pay for a Late Aircraft lists the flight numbers that pass a late aircraft on.
Source: US DOT Bureau of Transportation Statistics · Data covering October 2023 – July 2026
From pushback to gate
When it leaves ORD late, does that still matter by the time it reaches MKE?
On arrival at MKE, OO5555 spends 8.1 min taxiing from touchdown to the gate — ground time a connecting passenger sits through before they can even leave the aircraft, on top of however late the flight itself ran. That is 2.4 minutes longer than a typical MKE arrival (5.7 min).
Departure delay is averaged over every pushback and arrival delay over every completed arrival, so the two counts differ by the flights that never reached MKE. Taxi-out is gate to wheels up and sits inside the scheduled block rather than on top of it; the comparison is 45,592 departures from ORD scheduled in the clock hour OO5555 most often leaves in. Taxi-in is landing to gate, compared against every arrival FlyerIntel has on file at MKE (87,872 flights), not just OO5555’s own. More on taxi time.
Source: FlyerIntel analysis of US DOT BTS data · October 2023 – July 2026
The hour it leaves ORD
Part of any flight’s record belongs to the clock rather than to the flight. OO5555 has one departure time, so this is what that time is worth.
On-time arrival rate. 45,592 departures from ORD are scheduled in the 5 PM–6 PM hour over the period, against 952,802 across the whole day.
OO5555 is scheduled out of ORD at 5:50 PM, in the 5 PM–6 PM bank. Departures from ORD in that hour arrive on time 67.1% of the time against 74.5% across the airport’s whole day — the slot alone is worth 7.4 points worse before anything about this particular flight is considered.
The two airport figures cover every departure from ORD to every destination, so they describe the slot rather than this journey — the like-for-like comparison against the route is above. Hours are scheduled local, and a number whose schedule moved between banks inside the period has no single hour and is not described here at all. Why the hour matters.
Source: FlyerIntel analysis of US DOT BTS data · October 2023 – July 2026 · Hours below 120 departures are not scored.
By day of week
Does OO5555 run worse on particular days?
Saturday is historically the most reliable day and Sunday the least, a gap of 13.2 percentage points.
Source: FlyerIntel analysis of US DOT BTS data · October 2023 – July 2026 · Days with fewer than 120 operations are not scored.
Other routes OO5555 has flown
A flight number is a slot in a schedule, and carriers reassign it. These are the other city pairs this number served in the analysis period.
| Route | Operated | Flights | On time |
|---|---|---|---|
| BNA→ORD Nashville to Chicago | June 26, 2026 | 1 | — |
| SGF→DEN Springfield to Denver | September 29, 2023 – October 28, 2023 | 30 | — |
| XNA→DEN Fayetteville/Springdale/Rogers to Denver | September 5–28, 2023 | 24 | — |
| DEN→COS Denver to Colorado Springs | September 4, 2023 | 1 | — |
| CHS→ORD Charleston to Chicago | July 8, 2023 – August 26, 2023 | 28 | — |
Because the same number has served different journeys, the statistics above describe only the route OO5555 currently operates. Blending them would produce an average of two different flights.
When it goes wrong
The average describes a usual day. This is the day that ruins a connection.
99 min late
against a median of 3 min late
OO5555 has an average that understates its risk: a typical arrival is 3 min late, but the worst tenth are 96 minutes worse than that. If the trip has something unmissable at the end of it, the median is the wrong number to plan against.
Percentiles over 1,003 operations; cancelled and diverted flights are counted separately.
Source: US DOT Bureau of Transportation Statistics · Data covering October 2023 – July 2026
Other flights on this route
Same airports, same journey, different odds of arriving on time.
| Flight | Airline | On time | Median arrival | Operations |
|---|---|---|---|---|
| OO5262 | SkyWest Airlines | 73.7% | 3 min early | 752 |
| OO5320 | SkyWest Airlines | 72.2% | 1 min early | 784 |
| OO5225 | SkyWest Airlines | 68.7% | 2 min early | 841 |
| OO5555 this flight | SkyWest Airlines | 62.2% | 3 min late | 1,003 |
Every departure listed carries at least 600 operations, so the comparison is between figures that mean something. OO5555 is placed in the same ordering rather than left out of it; the rows around it are the most punctual departures on the route, not all of them, so this is a comparison and not a rank. Schedules change; confirm the departure still operates before booking around this.
Data and methodology
Calculated by FlyerIntel from 1,003 records of OO5555 operating ORD → MKE, published by the US DOT Bureau of Transportation Statistics. A flight counts as delayed when it arrives 15 or more minutes after schedule. Cancelled and diverted flights are excluded from the on-time rate and reported separately. Flight numbers are resolved as carrier plus number plus route, because the same number serves different routes over time.
Full methodology · Data sources · Report a problem
Related research: Most and Least Reliable Flight Numbers · The Delay You Inherit · Making Up Time in the Air
Analysis last recomputed