Flight number record

YX 4585

Republic Airways · Boston to Indianapolis

Route: BOS → IND
Departs: 17:00
Flights: 256
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 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 C−. 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 256 flights, with a median arrival 4 minutes early.

The national on-time rate over the same period is 77.6%, so YX 4585 runs 10 points behind the country as a whole. Across a thousand flights that is about 98 extra late arrivals.

On time

67.8%

Arrivals under 15 minutes late, of 245 completed flights

Avg delay

79 min

Across delayed arrivals only, not all flights

Cancelled

3.91%

National rate is 1.81%

1 hour+ late

14.3%

National rate is 8.1%

These figures cover 256 flights between July 2025 and June 2026. Beyond the headline rate, 14.3% 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 YX 4585 flies

YX 4585 flies BOS to IND without a single fixed slot. Its most common scheduled departure was 17:00, used on 58 of 256 flights, with 20:36 (46 flights) and 17:20 (26 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 17:0058 flights22.7%
Departs 20:3646 flights18.0%
Departs 17:2026 flights10.2%

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 YX 4585 runs level with that at 67.8%. 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

YX 4585 next to BOS to IND

Every carrier on BOS to IND combined arrived on time 81.6% of the time across 2,017 flights, so YX 4585 is 14 points behind it. Republic flew 1,962 flights on the same city pair under all its flight numbers, including this one, and those ran 81.9% on time. Across its whole network Republic Airways managed 78.5%, which this flight trails by 11 points.

YX 4585 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
YX 4585thin sample	256	67.8%	79 min	3.91%	C−
All Republic Airways on BOS–IND	1,962	81.9%	68 min	2.24%	B
All carriers on BOS–IND	2,017	81.6%	68 min	2.23%	B
Republic Airways, whole network	361,482	78.5%	72 min	4.08%	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 Oct–Dec 2025 at 62.5%, a swing of 11 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 202555 flights63.5%
Oct–Dec 202575 flights62.5%
Jan–Mar 202685 flights72.5%
Apr–Jun 202641 flights73.2%

Scale runs 55% to 80%. Rows with fewer than 30 flights show a dash.

By weekday, YX 4585 did best on Thursday at 81.6% on time and worst on Sunday at 48.7%. Each day rests on about 37 flights, so a gap of 33 points is worth noticing but could still narrow in another year.

Delay causes

Why YX 4585 runs late

One category carries most of the weight here. Late-arriving aircraft accounts for 72% of the 6,248 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.

Late-arriving aircraft
72%
National Airspace System
15%
Carrier
13%
Extreme weather
0%

72% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 6,248 reported delay minutes here, that single category outweighs weather by 72 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 6,248 delay minutes reported on YX 4585.

Cancellations run at 3.91%, against 1.81% 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

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 14.3% 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 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. 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 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. 256 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: 3.91% of its 256 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.

Where to go next

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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures