Carrier route record

NKBWI→IAH

Spirit Airlines · Baltimore to Houston

Flights: 376
Period: July 2025 to June 2026
Share of route: 29%
Carriers: 4

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

Spirit on BWI to IAH lands a B, about a point worse than the national rate of 77.6%. About one flight in four arrives 15 minutes late or worse, and those flights are late by close to two hours on average. That is a workable record, not a spotless one. That rests on 376 flights, with a median arrival 12 minutes early.

The US average over the same twelve months is 77.6%, so there is little to separate Spirit on BWI to IAH from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

76.5%

Arrivals under 15 minutes late, of 366 completed flights

Avg delay

108 min

Across delayed arrivals only, not all flights

Cancelled

2.66%

National rate is 1.81%

Whole route

79.8%

Every carrier on BWI to IAH, 1,311 flights

These figures cover 376 flights between July 2025 and June 2026. Beyond the headline rate, 11.5% 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

Spirit against every carrier on BWI to IAH

Spirit flew 376 of the 1,311 flights on BWI to IAH, about 29% of it. Its 76.5% on time is 3 points worse than the route as a whole, which runs 79.8%. Ranked by on-time rate it is number three of four carriers on the route, where the range runs from SkyWest at 100.0% to Frontier at 66.4%. Two 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.

On-time performance by carrier on BWI to IAH
Airline	Flights	On time	Avg delay	Cancelled	Grade
SkyWest Airlinesthin sample	1	100.0%	—	0.00%	A+
United Airlines	816	83.2%	80 min	1.10%	B
Spirit Airlines (this page)	376	76.5%	108 min	2.66%	B
Frontier Airlinesthin sample	118	66.4%	77 min	4.24%	C−

Departure window

When Spirit 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–8am56 flights85.7%
8am–11am29 flights—
11am–2pm94 flights81.9%
2pm–5pm40 flights81.6%
5pm–8pm70 flights61.8%
8pm–5am87 flights69.1%

Scale runs 55% to 90%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 61.8% on time, against 85.7% 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 11am–2pm window is the busiest, with 94 flights scheduled in it.

Across the year

Spirit on BWI to IAH through the year

Jul–Sep 2025129 flights86.6%
Oct–Dec 2025137 flights78.8%
Jan–Mar 202687 flights65.0%
Apr–Jun 202623 flights—

Scale runs 55% 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 76.5% on time across 376 flights.

Spirit on BWI to IAH did not run the same all year. Its best quarter was Jul–Sep 2025 at 86.6% on time and its weakest Jan–Mar 2026 at 65.0%, a swing of 22 points on roughly 125 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, Thursday is the strongest day at 85.7% on time and Monday the weakest at 67.2%. 19 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Spirit runs late on this route

Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 9,263 reported delay minutes.

Carrier
37%
National Airspace System
34%
Late-arriving aircraft
25%
Extreme weather
4%
Security
0%

The largest share of delay minutes, 37%, 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 3,438 of the 9,263 delay minutes reported here. The split is drawn from 9,263 reported delay minutes.

34% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 3,118 minutes out of 9,263, against a national NAS share of 21%.

Cancellations run at 2.66%, against 1.81% nationally. That is about one flight in 40 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

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 11.5% 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 1,235 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 runs 77.0% on time across 377 flights, within half a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

One caution: this is a thin sample. 376 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 Spirit on BWI to IAH

Put together: treat all of this as provisional. 376 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 76.5% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 366 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