Carrier route record
MQSTL→BOS
Envoy Air · St. Louis to Boston
- Flights
- 418
- Period
- July 2025 to June 2026
- Share of route
- 26%
- Carriers
- 3
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Envoy Air.
Envoy on STL to BOS sits in the middle of the pack with a B. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 418 flights, with a median arrival 10 minutes early.
The US average over the same twelve months is 77.6%, so there is little to separate Envoy on STL to BOS from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
75.9%
Arrivals under 15 minutes late, of 411 completed flights
Avg delay
79 min
Across delayed arrivals only, not all flights
Cancelled
1.67%
National rate is 1.81%
Whole route
70.3%
Every carrier on STL to BOS, 1,610 flights
These figures cover 418 flights between July 2025 and June 2026. Beyond the headline rate, 10.9% 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.
Carrier by carrier
Envoy against every carrier on STL to BOS
Envoy flew 418 of the 1,610 flights on STL to BOS, about 26% of it. Its 75.9% on time is 6 points better than the route as a whole, which runs 70.3%. Ranked by on-time rate it is number two of three carriers on the route, where the range runs from Republic at 76.0% to Southwest at 66.3%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Republic Airwaysthin sample | 258 | 76.0% | 88 min | 3.10% | B− |
| Envoy Air (this page) | 418 | 75.9% | 79 min | 1.67% | B |
| Southwest Airlines | 934 | 66.3% | 59 min | 0.96% | C+ |
Departure window
When Envoy runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 24 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am—
- 8am–11am148 flights87.8%
- 11am–2pm13 flights—
- 2pm–5pm91 flights78.4%
- 5pm–8pm166 flights64.2%
- 8pm–5am—
Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 64.2% on time, against 87.8% for the 8am–11am 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 5pm–8pm window is the busiest, with 166 flights scheduled in it.
Across the year
Envoy on STL to BOS through the year
- Jul–Sep 2025145 flights84.7%
- Oct–Dec 2025111 flights66.4%
- Jan–Mar 202684 flights73.4%
- Apr–Jun 202678 flights75.6%
Scale runs 60% to 90%. 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 75.9% on time across 418 flights.
Envoy on STL to BOS did not run the same all year. Its best quarter was Jul–Sep 2025 at 84.7% on time and its weakest Oct–Dec 2025 at 66.4%, a swing of 18 points on roughly 105 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, Tuesday is the strongest day at 83.6% on time and Thursday the weakest at 62.9%. 21 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Envoy runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 60% of the 7,785 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.
- 60%Late-arriving aircraft
- 19%National Airspace System
- 17%Carrier
- 4%Extreme weather
- 0%Security
60% 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 7,785 reported delay minutes here, that single category outweighs weather by 16 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 7,785 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 87.8% on time here.
Cancellations sit at 1.67% against a national 1.81%, which is ordinary. Diversions add another 0.00%.
Connections and stage length
What a delay here costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.9% 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 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 82.2% on time across 418 flights, 6 points above 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. 418 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 Envoy on STL to BOS
Put together: treat all of this as provisional. 418 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 75.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 411 completed flights over 12 months sit behind that.
Related
Where to go next
- STL to BOS, every carrier
- Envoy on BOS to STL, the return leg
- Republic Airways on STL to BOS76.0%
- Southwest Airlines on STL to BOS66.3%
- Envoy Air network-wide record
- St. Louis Lambert International (STL) delay statistics
- Boston Logan International (BOS) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
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.