Route reliability record

BWI→DTW

Baltimore to Detroit

Flights: 2,257
Period: July 2025 to June 2026
Distance: 409 mi
Carriers: 5

This route lands a B, 4 points better than the national rate of 77.6%. Roughly one flight in five arrive 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 2,257 flights, of which Delta Air Lines flew 1,204 at 86.8% on time.

Set against the rest of the country, this route's record is 4 points better than the US average of 77.6%. That gap is worth roughly 41 fewer late arrivals for every thousand flights.

On time

81.7%

Arrivals under 15 minutes late, of 2,217 completed flights

Avg delay

78 min

Across delayed arrivals only, not all flights

Cancelled

1.77%

National rate is 1.81%

Best carrier

Delta

86.8% on time across 1,204 flights

These figures cover 2,257 flights between July 2025 and June 2026. The median arrival is 9 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

Which airline is most reliable on BWI to DTW

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 86.8% of the time; Southwest Airlines manages 75.8%. Sample sizes sit next to every figure, because a two-point gap across 785 flights means less than a ten-point one.

On-time performance by carrier on BWI to DTW
Airline	Flights	On time	Avg delay	Cancelled	Grade
Republic Airwaysthin sample	14	92.3%	17 min	7.14%	A−
Delta Air Lines	1,204	86.8%	103 min	1.66%	A
Spirit Airlinesthin sample	106	77.1%	104 min	0.94%	B+
Southwest Airlines	785	75.8%	57 min	1.91%	B
Frontier Airlinesthin sample	148	73.1%	66 min	2.03%	C

Delta leads Southwest by 11 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Departure window

The best time of day to leave

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 26 points, against 11 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am382 flights92.8%
8am–11am421 flights84.2%
11am–2pm510 flights89.7%
2pm–5pm148 flights73.5%
5pm–8pm428 flights75.3%
8pm–5am368 flights66.8%

Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 92.8% of the time, against 66.8% for the overnight window. That is 26 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 510 flights scheduled in it.

Across the year

When delays peak on this route

This route's year swings by 20 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.

Darker means more delays. Figures are on-time percentages.October best, December worst

December is the weak month at 70.6% on time, against 90.9% in October. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. October was the busiest month here, with 231 flights.

Across the week, Tuesday is the strongest day at 87.0% on time and Sunday the weakest at 74.7%. 12 points is a smaller lever than departure hour, but it is free.

Delay causes

Why this route gets delayed

One category carries most of the weight here. Late-arriving aircraft accounts for 50% of the 31,000 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
50%
Carrier
34%
National Airspace System
14%
Extreme weather
2%
Security
0%

50% 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 31,000 reported delay minutes here, that single category outweighs weather by 23 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 31,186 reported delay minutes.

The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 92.8% on time here.

Cancellations sit at 1.77% against a national 1.81%, which is ordinary. Diversions add another 0.00%.

Connections and stage length

What a delay here actually costs

6.4% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route are the a little over an hour kind, which a normal layover absorbs.

At 409 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 5am–8am window matters as much as it does.

The return leg runs 80.9% on time across 2,261 flights, within about a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

The sample behind these figures is 2,257 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.

What to do with this

Booking this route

Put together: the calendar is the biggest lever here, not the carrier or the hour. October runs 90.9% on time and December 70.6%, a swing of 20 points. If the dates move at all, move them out of December before you think about anything else. 2,217 completed flights over 12 months sit behind that.

Common questions

BWI to DTW questions

How often is BWI to DTW delayed?

Roughly one flight in five arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 18.3% of the 2,257 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.

Which airline is most reliable on BWI to DTW?

Delta Air Lines leads at 86.8% on time across 1,204 flights. Southwest Airlines is at the other end on 75.8%, a gap of 11 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.

What time of day has the fewest delays on BWI to DTW?

The 5am–8am departure window is the strongest at 92.8% on time. The 8pm–5am window is the weakest at 66.8%, 26 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.

How bad are December delays on BWI to DTW?

December is the weakest month at 70.6% on time, compared with 90.9% in October. Across the year that is 20 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.

Where to go next

Direction matters. BWI to DTW and DTW to BWI are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.

Key figures