Flight number record

YX 4637

Republic Airways · Philadelphia to Indianapolis

Route: PHL → IND
Departs: 18:40
Flights: 320
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 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 C−. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 320 flights, with a median arrival 10 minutes early.

The national on-time rate over the same period is 77.6%, so YX 4637 runs 4 points behind the country as a whole. Across a thousand flights that is about 41 extra late arrivals.

On time

73.5%

Arrivals under 15 minutes late, of 302 completed flights

Avg delay

77 min

Across delayed arrivals only, not all flights

Cancelled

5.31%

National rate is 1.81%

1 hour+ late

9.9%

National rate is 8.1%

These figures cover 320 flights between July 2025 and June 2026. Beyond the headline rate, 9.9% 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 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 18:45 (56 flights) and 18:15 (35 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 18:4084 flights26.3%
Departs 18:4556 flights17.5%
Departs 18:1535 flights10.9%

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 18:40 departure sits in the 5pm–8pm window. Across every US flight scheduled in that window the on-time rate is 68.2%, and YX 4637 runs 5 points better at 73.5%. 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

YX 4637 next to PHL to IND

Every carrier on PHL to IND combined arrived on time 75.9% of the time across 1,549 flights, so YX 4637 is 2 points behind it. Republic flew 601 flights on the same city pair under all its flight numbers, including this one, and those ran 79.9% on time. Across its whole network Republic Airways managed 78.5%, which this flight trails by 5 points.

YX 4637 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
YX 4637thin sample	320	73.5%	77 min	5.31%	C−
All Republic Airways on PHL–IND	601	79.9%	74 min	3.99%	B−
All carriers on PHL–IND	1,549	75.9%	71 min	3.74%	B−
Republic Airways, whole network	361,482	78.5%	72 min	4.08%	B−

Across the year

YX 4637 quarter by quarter

Quarter by quarter YX 4637 held fairly steady: 69.1% in Jul–Sep 2025, 71.1% in Oct–Dec 2025, 78.8% in Jan–Mar 2026 and 76.1% in Apr–Jun 2026. A spread of 10 points is about what a sample of this size moves on its own, so the annual figure is a fair summary.

Jul–Sep 202592 flights69.1%
Oct–Dec 202591 flights71.1%
Jan–Mar 202690 flights78.8%
Apr–Jun 202647 flights76.1%

Scale runs 60% to 85%. Rows with fewer than 30 flights show a dash.

By weekday, YX 4637 did best on Tuesday at 81.4% on time and worst on Sunday at 59.5%. Each day rests on about 46 flights, so a gap of 22 points is worth noticing but could still narrow in another year.

Delay causes

Why YX 4637 runs late

One category carries most of the weight here. Late-arriving aircraft accounts for 47% of the 6,166 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
47%
National Airspace System
20%
Extreme weather
19%
Carrier
14%

Extreme weather accounts for 19% 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 3.1 times the usual weather exposure. The split is drawn from 6,166 delay minutes reported on YX 4637.

Cancellations run at 5.31%, against 1.81% nationally. That is about one flight in twenty 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. 9.9% 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 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. 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.

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: 5.31% of its 320 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