Flight number record
YX 4585
Republic Airways · Boston to Indianapolis
- Route
- BOS → IND
- Departs
- 20:36
- Flights
- 255
- Period
- September 2025 to August 2026
Historical statistics for September 2025 to August 2026, not live status. For today’s YX 4585, 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 4585 draws a D−. About one flight in three arrives at least 15 minutes late, and the typical late arrival is a little over an hour behind schedule. Build slack into anything you connect to. That rests on 255 flights, with a median arrival right on schedule.
The national on-time rate over the same period is 77.3%, so YX 4585 runs 13 points behind the country as a whole. Across a thousand flights that is about 131 extra late arrivals.
Key figures
On time
64.2%
Arrivals under 15 minutes late, of 243 completed flights
Avg delay
79 min
Across delayed arrivals only, not all flights
Cancelled
4.31%
National rate is 1.89%
1 hour+ late
15.2%
National rate is 8.3%
These figures cover 255 flights between September 2025 and August 2026. Beyond the headline rate, 15.2% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Schedule
When YX 4585 flies
YX 4585 flies BOS to IND without a single fixed slot. Its most common scheduled departure was 20:36, used on 46 of 255 flights, with 17:00 (41 flights) next.
- Departs 20:3646 flights18.0%
- Departs 17:0041 flights16.1%
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 20:36 departure sits in the 8pm–5am window. Across every US flight scheduled in that window the on-time rate is 70.1%, and YX 4585 runs 6 points worse at 64.2%. 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 4585 next to BOS to IND
Every carrier on BOS to IND combined arrived on time 80.3% of the time across 2,025 flights, so YX 4585 is 16 points behind it. Republic flew 1,975 flights on the same city pair under all its flight numbers, including this one, and those ran 80.5% on time. Across its whole network Republic Airways managed 78.1%, which this flight trails by 14 points.
| Compared with | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| YX 4585thin sample | 255 | 64.2% | 79 min | 4.31% | D− |
| All Republic Airways on BOS–IND | 1,975 | 80.5% | 69 min | 2.43% | B |
| All carriers on BOS–IND | 2,025 | 80.3% | 69 min | 2.42% | B |
| Republic Airways, whole network | 364,452 | 78.1% | 74 min | 4.55% | B− |
Across the year
YX 4585 quarter by quarter
YX 4585 did not run the same all year. Its best quarter was Apr–Jun 2026 at 73.2% on time and its weakest Jul–Sep 2026 at 45.8%, a swing of 27 points on roughly 64 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 20252 flights—
- Oct–Dec 202575 flights62.5%
- Jan–Mar 202685 flights72.5%
- Apr–Jun 202641 flights73.2%
- Jul–Sep 202652 flights45.8%
Scale runs 35% to 80%. Rows with fewer than 30 flights show a dash.
By weekday, YX 4585 did best on Thursday at 74.4% on time and worst on Sunday at 43.6%. Each day rests on about 36 flights, so a gap of 31 points is worth noticing but could still narrow in another year.
Arrival by arrival
How late YX 4585 runs when it is late
YX 4585 often beats the schedule: 77 of 243 completed flights, 32%, arrived 15 minutes or more early. The 87 late arrivals split 26 under half an hour, 24 between 30 and 60 minutes, and 37 an hour or more.
- 15+ min early77 flights31.7%
- Within 15 min79 flights32.5%
- 15–29 min late26 flights10.7%
- 30–59 min late24 flights9.9%
- 1–2 hours late18 flights7.4%
- 2+ hours late19 flights7.8%
Scale runs 0% to 100%.
Share of 243 completed flights by arrival against schedule.
14 of 88 late departures made up the time and arrived on time, 16% of them. In the other direction, 13 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at IND.
The worst days
Worst days for YX 4585
The latest arrival of the period was on 9 July 2026, 5 hours 54 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). On four of the five worst days the largest share was filed as a late-arriving aircraft.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 9 July 2026 | 5 hours 54 minutes | Carrier |
| 14 October 2025 | 5 hours 21 minutes | Late-arriving aircraft |
| 4 August 2026 | 4 hours 27 minutes | Late-arriving aircraft |
| 28 December 2025 | 4 hours 14 minutes | Late-arriving aircraft |
| 14 December 2025 | 4 hours 8 minutes | Late-arriving aircraft |
Delay causes
Why YX 4585 runs late
Late-arriving aircraft accounts for 70% of the 6,890 delay minutes carriers reported here, and the remaining four split what is left.
- 70%Late-arriving aircraft
- 16%Carrier
- 14%National Airspace System
- 0%Extreme weather
70% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 6,890 reported delay minutes here, that single category outweighs weather by 70 to one. The split is drawn from 6,890 delay minutes reported on YX 4585.
Cancellations run at 4.31%, 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
15.2% 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 818 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 BOS to LGA (28), but none flew often enough under YX 4585 to report a rate for. Carriers move flight numbers between routes, so the figures on this page apply to BOS to IND only.
One caution: this is a thin sample. 255 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 4585
For a booking, the cancellation rate is the figure to plan around on YX 4585: 4.31% of its 255 scheduled flights did not operate. A late arrival costs a little over an hour, but a cancellation costs the day, so leave a later option open.
Related
Where to go next
- BOS to IND, every carrier and departure
- IND to BOS, the return direction
- Republic Airways 5616 on the same route75.6%
- Republic Airways 5627 on the same route82.0%
- Republic Airways 4725 on the same route88.4%
- Boston Logan International (BOS) 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.