Carrier route record

F9BWI→MIA

Frontier Airlines · Baltimore to Miami

Flights: 265
Period: July 2025 to June 2026
Share of route: 12%
Carriers: 5

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

Frontier on BWI to MIA sits in the middle of the pack with a C−. About seven flights in ten arrive on time by the DOT's definition, 8 points worse than the national rate of 77.6%. The late ones land an hour and a half behind schedule. That rests on 265 flights. The strongest carrier on the route with a full sample, American Airlines, flew 689 at 80.4% on time.

The national on-time rate over the same period is 77.6%, so Frontier on BWI to MIA runs 8 points behind the country as a whole. Across a thousand flights that is about 82 extra late arrivals.

On time

69.4%

Arrivals under 15 minutes late, of 255 completed flights

Avg delay

89 min

Across delayed arrivals only, not all flights

Cancelled

3.40%

National rate is 1.81%

Whole route

74.7%

Every carrier on BWI to MIA, 2,286 flights

These figures cover 265 flights between July 2025 and June 2026. Beyond the headline rate, 15.3% 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

Frontier against every carrier on BWI to MIA

Frontier flew 265 of the 2,286 flights on BWI to MIA, about 12% of it. Its 69.4% on time is 5 points worse than the route as a whole, which runs 74.7%. Ranked by on-time rate it is number four of five carriers on the route, where the range runs from Envoy at 81.6% to Spirit at 61.1%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The choice of carrier is not cosmetic here. American Airlines arrives on time 80.4% of the time; Southwest Airlines manages 72.3%. Sample sizes sit next to every figure, because a two-point gap across 1,181 flights means less than a ten-point one.

On-time performance by carrier on BWI to MIA
Airline	Flights	On time	Avg delay	Cancelled	Grade
Envoy Airthin sample	114	81.6%	62 min	0.00%	B+
American Airlines	689	80.4%	101 min	2.32%	B
Southwest Airlines	1,181	72.3%	59 min	1.86%	C
Frontier Airlines (this page)thin sample	265	69.4%	89 min	3.40%	C−
Spirit Airlinesthin sample	37	61.1%	64 min	2.70%	D

American leads Southwest by 8 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Departure window

When Frontier runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 31 points, against 8 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am—
8am–11am45 flights88.1%
11am–2pm49 flights87.2%
2pm–5pm45 flights57.1%
5pm–8pm107 flights58.5%
8pm–5am19 flights—

Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.

Book the morning departure. Flights leaving between 8am–11am arrive on time 88.1% of the time, against 57.1% for the afternoon window. That is 31 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5pm–8pm window is the busiest, with 107 flights scheduled in it.

Across the year

Frontier on BWI to MIA through the year

Jul–Sep 202579 flights62.3%
Oct–Dec 202556 flights77.8%
Jan–Mar 202660 flights76.8%
Apr–Jun 202670 flights64.7%

Scale runs 55% to 85%. 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 69.4% on time across 265 flights.

Frontier on BWI to MIA did not run the same all year. Its best quarter was Oct–Dec 2025 at 77.8% on time and its weakest Jul–Sep 2025 at 62.3%, a swing of 16 points on roughly 66 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 82.9% on time and Friday the weakest at 61.7%. 21 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Frontier runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 57% of the 6,965 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
57%
National Airspace System
32%
Carrier
10%
Extreme weather
1%

57% 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 6,965 reported delay minutes here, that single category outweighs weather by 39 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 6,965 reported delay minutes.

32% 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 2,241 minutes out of 6,965, against a national NAS share of 21%.

Cancellations run at 3.40%, 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

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 15.3% 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 946 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 74.2% on time across 265 flights, 5 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 5 points of difference.

One caution: this is a thin sample. 265 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 Frontier on BWI to MIA

Put together: the delay figures matter less here than the 3.40% cancellation rate. A late arrival costs you an hour and a half; a cancelled flight costs you the day. Book the 8am–11am departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 255 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