Flight number record

YX 5631

Republic Airways · Indianapolis to Boston

Route: IND → BOS
Departs: 06:00
Flights: 364
Period: July 2025 to June 2026

Historical statistics for July 2025 to June 2026, not live status. For today’s YX 5631, 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 5631 earns an A. Nearly every flight arrives inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 16 points better than the national rate of 77.6%. When something does go wrong the average delay runs about 40 minutes. That rests on 364 flights, with a median arrival 18 minutes early.

Set against the rest of the country, YX 5631's record is 16 points better than the US average of 77.6%. That gap is worth roughly 157 fewer late arrivals for every thousand flights.

On time

93.3%

Arrivals under 15 minutes late, of 358 completed flights

Avg delay

40 min

Across delayed arrivals only, not all flights

Cancelled

1.65%

National rate is 1.81%

1 hour+ late

0.8%

National rate is 8.1%

These figures cover 364 flights between July 2025 and June 2026. The median arrival is 18 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.

Schedule

When YX 5631 flies

YX 5631 flies IND to BOS without a single fixed slot. Its most common scheduled departure was 06:00, used on 85 of 364 flights, with 06:15 (82 flights) next. Carriers retime flights through the season, so the rates here blend slightly different positions in the aircraft's day.

Departs 06:0085 flights23.4%
Departs 06:1582 flights22.5%

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 06:00 departure sits in the 5am–8am window. Across every US flight scheduled in that window the on-time rate is 89.3%, and YX 5631 runs 4 points better at 93.3%. Early departures usually start with an aircraft that has not flown yet that day, which is most of why the window does well.

Against the route

YX 5631 next to IND to BOS

Every carrier on IND to BOS combined arrived on time 78.2% of the time across 2,016 flights, so YX 5631 is 15 points ahead of it. Republic flew 1,961 flights on the same city pair under all its flight numbers, including this one, and those ran 78.2% on time. Across its whole network Republic Airways managed 78.5%, which this flight beats by 15 points.

YX 5631 against its route and carrier
Compared with	Flights	On time	Avg delay	Cancelled	Grade
YX 5631thin sample	364	93.3%	40 min	1.65%	A
All Republic Airways on IND–BOS	1,961	78.2%	67 min	2.60%	B
All carriers on IND–BOS	2,016	78.2%	67 min	2.58%	B
Republic Airways, whole network	361,482	78.5%	72 min	4.08%	B−

Across the year

YX 5631 quarter by quarter

YX 5631 did not run the same all year. Its best quarter was Apr–Jun 2026 at 98.9% on time and its weakest Jan–Mar 2026 at 86.9%, a swing of 12 points on roughly 91 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 202591 flights96.7%
Oct–Dec 202592 flights90.2%
Jan–Mar 202690 flights86.9%
Apr–Jun 202691 flights98.9%

Scale runs 80% to 100%. Rows with fewer than 30 flights show a dash.

By weekday, YX 5631 did best on Sunday at 100.0% on time and worst on Monday at 82.0%. Each day rests on about 52 flights, so a gap of 18 points is worth noticing but could still narrow in another year.

Delay causes

Why YX 5631 runs late

One category carries most of the weight here. National Airspace System accounts for 59% of the 966 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.

National Airspace System
59%
Carrier
29%
Extreme weather
12%

Extreme weather accounts for 12% 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 2.0 times the usual weather exposure. The split is drawn from 966 delay minutes reported on YX 5631.

Cancellations sit at 1.65% against a national 1.81%, which is ordinary. Diversions add another 0.00%.

Connections and routes

What a delay on this flight costs

Badly late arrivals are rare here: only 0.8% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.

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.

Every one of the 364 flights under YX 5631 in the data flew IND to BOS. 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. 364 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 5631

For a booking, read YX 5631 as 93.3% on time with 1.65% cancelled over 364 flights. Those are rates from the past twelve months, not a forecast for any particular day.

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