Carrier route record

YXBOS→STL

Republic Airways · Boston to St. Louis

Flights: 258
Period: July 2025 to June 2026
Share of route: 16%
Carriers: 3

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Republic Airways.

Republic on BOS to STL lands a B−, 5 points better than the national rate of 77.6%. About one flight in six arrives 15 minutes late or worse, and those flights are late by roughly 50 minutes on average. That is a workable record, not a spotless one. That rests on 258 flights. The strongest carrier on the route with a full sample, Envoy Air, flew 418 at 82.2% on time.

Set against the rest of the country, Republic's BOS to STL record is 5 points better than the US average of 77.6%. That gap is worth roughly 47 fewer late arrivals for every thousand flights.

On time

82.3%

Arrivals under 15 minutes late, of 248 completed flights

Avg delay

49 min

Across delayed arrivals only, not all flights

Cancelled

3.10%

National rate is 1.81%

Whole route

76.5%

Every carrier on BOS to STL, 1,611 flights

These figures cover 258 flights between July 2025 and June 2026. The median arrival is 12 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.

Carrier by carrier

Republic against every carrier on BOS to STL

Republic flew 258 of the 1,611 flights on BOS to STL, about 16% of it. Its 82.3% on time is 6 points better than the route as a whole, which runs 76.5%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from Republic at 82.3% to Southwest at 72.4%.

The choice of carrier is not cosmetic here. Envoy Air arrives on time 82.2% of the time; Southwest Airlines manages 72.4%. Sample sizes sit next to every figure, because a two-point gap across 935 flights means less than a ten-point one.

On-time performance by carrier on BOS to STL
Airline	Flights	On time	Avg delay	Cancelled	Grade
Republic Airways (this page)thin sample	258	82.3%	49 min	3.10%	B−
Envoy Air	418	82.2%	74 min	1.20%	B
Southwest Airlines	935	72.4%	62 min	0.96%	C+

Envoy leads Southwest by 10 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Departure window

When Republic runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 36 points, against 10 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am87 flights90.4%
8am–11am102 flights84.7%
11am–2pm6 flights—
2pm–5pm29 flights—
5pm–8pm34 flights54.5%
8pm–5am—

Scale runs 45% to 95%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 54.5% on time, against 90.4% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 8am–11am window is the busiest, with 102 flights scheduled in it.

Across the year

Republic on BOS to STL through the year

Jul–Sep 202524 flights—
Oct–Dec 202558 flights91.2%
Jan–Mar 202682 flights83.1%
Apr–Jun 202694 flights76.9%

Scale runs 70% to 95%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 82.3% on time across 258 flights.

Republic on BOS to STL did not run the same all year. Its best quarter was Oct–Dec 2025 at 91.2% on time and its weakest Apr–Jun 2026 at 76.9%, a swing of 14 points on roughly 86 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.

Across the week, Wednesday is the strongest day at 89.2% on time and Sunday the weakest at 72.1%. 17 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Republic runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 43% of the 2,146 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
43%
Carrier
38%
National Airspace System
19%

43% 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 2,146 reported delay minutes here, that single category outweighs weather by 43 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 2,146 reported delay minutes.

The largest share of delay minutes, 38%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 816 of the 2,146 delay minutes reported here.

Cancellations run at 3.10%, against 1.81% nationally. That is about one flight in 30 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 stage length

What a delay here costs

Badly late arrivals are rare here: only 4.4% 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 1,047 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 return leg is a different operation and performs like one: it runs 76.0% on time across 258 flights, 6 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 6 points of difference.

One caution: this is a thin sample. 258 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 Republic on BOS to STL

Put together: the delay figures matter less here than the 3.10% cancellation rate. A late arrival costs you roughly 50 minutes; a cancelled flight costs you the day. Book the 5am–8am departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 248 completed flights over 12 months sit behind that.

Where to go next

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