Flight number record
YX 4637
Republic Airways · Philadelphia to Indianapolis
- Route
- PHL → IND
- Departs
- 18:40
- Flights
- 320
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s YX 4637, check with Republic Airways. Republic Airways flies under contract for larger airlines, so a ticket for this flight may show a different airline code and number.
YX 4637 sits in the middle of the pack with a B−. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.3%. The late ones land an hour and a half behind schedule. That rests on 320 flights, with a median arrival 11 minutes early.
Key figures
On time
75.6%
Arrivals under 15 minutes late, of 308 completed flights
Avg delay
97 min
Across delayed arrivals only, not all flights
Cancelled
3.75%
National rate is 1.89%
1 hour+ late
12.3%
National rate is 8.3%
These figures cover 320 flights between September 2025 and August 2026. Beyond the headline rate, 12.3% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When YX 4637 flies
YX 4637 flies PHL to IND without a single fixed slot. Its most common scheduled departure was 18:40, used on 84 of 320 flights, with 18:35 (56 flights) and 18:15 (36 flights) next.
- Departs 18:4084 flights26.3%
- Departs 18:3556 flights17.5%
- Departs 18:1536 flights11.3%
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 18:40 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.0%, and YX 4637 runs 8 points better at 75.6%. By that time of day most aircraft have flown several legs already, and whatever went wrong earlier is still in the schedule.
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Against the route
YX 4637 next to PHL to IND
Every carrier on PHL to IND combined arrived on time 76.3% of the time across 1,594 flights, so YX 4637 is about level with it. Republic flew 571 flights on the same city pair under all its flight numbers, including this one, and those ran 80.6% on time. Across its whole network Republic Airways managed 78.1%, which this flight trails by 3 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| YX 4637thin sample | 320 | 75.6% | 97 min | 3.75% | B− |
| All Republic Airways on PHL–IND | 571 | 80.6% | 87 min | 3.33% | B− |
| All carriers on PHL–IND | 1,594 | 76.3% | 79 min | 4.27% | B− |
| Republic Airways, whole network | 364,452 | 78.1% | 74 min | 4.55% | B− |
Across the year
YX 4637 quarter by quarter
YX 4637 did not run the same all year. Its best quarter was Jan–Mar 2026 at 78.8% on time and its weakest Jul–Sep 2026 at 67.2%, a swing of 12 points on roughly 80 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 202530 flights—
- Oct–Dec 202591 flights71.1%
- Jan–Mar 202690 flights78.8%
- Apr–Jun 202647 flights76.1%
- Jul–Sep 202662 flights67.2%
Scale runs 60% to 85%. Rows with fewer than 30 flights show a dash.
By weekday, YX 4637 did best on Tuesday at 83.7% on time and worst on Sunday at 65.1%. Each day rests on about 46 flights, so a gap of 19 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late YX 4637 runs when it is late
YX 4637 often beats the schedule: 134 of 308 completed flights, 44%, arrived 15 minutes or more early. When YX 4637 is late it tends to be very late: 38 of its 75 late arrivals were an hour or more behind, and 22 were two hours or more.
- 15+ min early134 flights43.5%
- Within 15 min99 flights32.1%
- 15–29 min late10 flights3.2%
- 30–59 min late27 flights8.8%
- 1–2 hours late16 flights5.2%
- 2+ hours late22 flights7.1%
Scale runs 0% to 100%.
Share of 308 completed flights by arrival against schedule.
14 of 75 late departures made up the time and arrived on time, 19% of them. 14 flights left on time and still arrived late.
The worst days
Worst days for YX 4637
The latest arrival of the period was on 13 December 2025, 11 hours 54 minutes behind schedule; most of its delay minutes were filed as extreme weather. On three of the five worst days the largest share was filed as a late-arriving aircraft.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 13 December 2025 | 11 hours 54 minutes | Extreme weather |
| 11 June 2026 | 5 hours 40 minutes | Extreme weather |
| 2 August 2026 | 5 hours 36 minutes | Late-arriving aircraft |
| 16 August 2026 | 5 hours 9 minutes | Late-arriving aircraft |
| 7 July 2026 | 4 hours 33 minutes | Late-arriving aircraft |
Delay causes
Why YX 4637 runs late
Late-arriving aircraft accounts for 52% of the 7,285 delay minutes carriers reported here, and the remaining four split what is left.
- 52%Late-arriving aircraft
- 20%Extreme weather
- 16%National Airspace System
- 12%Carrier
Extreme weather accounts for 20% 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 3.3 times the usual weather exposure. The split is drawn from 7,285 delay minutes reported on YX 4637.
Cancellations run at 3.75%, against 1.89% nationally. That is about one flight in 25 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.
Connections and routes
What a delay on this flight costs
12.3% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
The 588 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.
Every one of the 320 flights under YX 4637 in the data flew PHL to IND. The number was not reused on any other city pair, which makes this a clean record of one route.
One caution: this is a thin sample. 320 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 YX 4637
For a booking, the cancellation rate is the figure to plan around on YX 4637: 3.75% of its 320 scheduled flights did not operate. A late arrival costs an hour and a half, but a cancellation costs the day, so leave a later option open.
Related
Where to go next
- PHL to IND, every carrier and departure
- IND to PHL, the return direction
- Philadelphia International (PHL) delay statistics
- Indianapolis International (IND) delay statistics
- Republic Airways on-time record
- Every Republic Airways flight number with a record
- The most and least reliable flight numbers in the US
- Why the first flight of the morning is statistically safest
A flight number here means Republic Airways’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.