Flight number record
UA 308
United Airlines · Philadelphia to Chicago
- Route
- PHL → ORD
- Departs
- 17:00
- Flights
- 297
- Period
- July 2025 to June 2026
Historical statistics for July 2025 to June 2026, not live status. For today’s UA 308, check with United Airlines.
UA 308 draws a D. Roughly one flight in three arrives at least 15 minutes late, and the typical late arrival is an hour and a half behind schedule. Build slack into anything you connect to. That rests on 297 flights, with a median arrival 7 minutes late.
The national on-time rate over the same period is 77.6%, so UA 308 runs 17 points behind the country as a whole. Across a thousand flights that is about 171 extra late arrivals.
Key figures
On time
60.5%
Arrivals under 15 minutes late, of 291 completed flights
Avg delay
94 min
Across delayed arrivals only, not all flights
Cancelled
1.35%
National rate is 1.81%
1 hour+ late
14.4%
National rate is 8.1%
These figures cover 297 flights between July 2025 and June 2026. Beyond the headline rate, 14.4% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Schedule
When UA 308 flies
UA 308 flies PHL to ORD without a single fixed slot. Its most common scheduled departure was 17:00, used on 75 of 297 flights, with 17:16 (49 flights) and 16:59 (32 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.
- Departs 17:0075 flights25.3%
- Departs 17:1649 flights16.5%
- Departs 16:5932 flights10.8%
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 17:00 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.2%, and UA 308 runs 8 points worse at 60.5%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.
Against the route
UA 308 next to PHL to ORD
Every carrier on PHL to ORD combined arrived on time 73.0% of the time across 4,911 flights, so UA 308 is 13 points behind it. United flew 1,773 flights on the same city pair under all its flight numbers, including this one, and those ran 74.0% on time. Across its whole network United Airlines managed 79.0%, which this flight trails by 19 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| UA 308thin sample | 297 | 60.5% | 94 min | 1.35% | D |
| All United Airlines on PHL–ORD | 1,773 | 74.0% | 94 min | 1.75% | C |
| All carriers on PHL–ORD | 4,911 | 73.0% | 99 min | 3.12% | C− |
| United Airlines, whole network | 821,041 | 79.0% | 72 min | 1.01% | B |
Across the year
UA 308 quarter by quarter
UA 308 did not run the same all year. Its best quarter was Jan–Mar 2026 at 73.6% on time and its weakest Jul–Sep 2025 at 47.1%, a swing of 26 points on roughly 74 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 202592 flights47.1%
- Oct–Dec 202561 flights57.4%
- Jan–Mar 202653 flights73.6%
- Apr–Jun 202691 flights67.8%
Scale runs 40% to 80%. Rows with fewer than 30 flights show a dash.
By weekday, UA 308 did best on Monday at 67.5% on time and worst on Sunday at 51.2%. Each day rests on about 42 flights, so a gap of 16 points is worth noticing but could still narrow in another year.
Delay causes
Why UA 308 runs late
One category carries most of the weight here. National Airspace System accounts for 63% of the 11,000 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.
- 63%National Airspace System
- 21%Carrier
- 15%Late-arriving aircraft
- 1%Extreme weather
63% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 6,822 minutes out of 11,000, against a national NAS share of 21%. The split is drawn from 10,804 delay minutes reported on UA 308.
Cancellations sit at 1.35% against a national 1.81%, which is ordinary. Diversions add another 0.67%.
Connections and routes
What a delay on this flight costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 14.4% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
The 678 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 six other city pairs in the data, including ORD to SNA (167), ORD to LGA (36) and ORD to ONT (26), but none flew often enough under UA 308 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to PHL to ORD only.
One caution: this is a thin sample. 297 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 UA 308
For a booking, UA 308 is a flight to put a long connection behind. 14.4% of its completed flights arrived an hour or more late, which a short layover will not absorb. If the onward flight is on a separate ticket, the risk sits with you.
Related
Where to go next
- PHL to ORD, every carrier and departure
- ORD to PHL, the return direction
- Philadelphia International (PHL) delay statistics
- Chicago O'Hare International (ORD) delay statistics
- United Airlines on-time record
- Every United Airlines flight number with a record
- The most and least reliable flight numbers in the US
- How often a connection fails at the major US hubs
A flight number here means United 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.