Route reliability record

MIA→AUS

Miami to Austin

Flights: 2,161
Period: July 2025 to June 2026
Distance: 1,103 mi
Carriers: 5

This route sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 5 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 2,161 flights, with a median arrival 5 minutes early.

The national on-time rate over the same period is 77.6%, so this route runs 5 points behind the country as a whole. Across a thousand flights that is about 48 extra late arrivals.

On time

72.8%

Arrivals under 15 minutes late, of 2,134 completed flights

Avg delay

73 min

Across delayed arrivals only, not all flights

Cancelled

1.06%

National rate is 1.81%

Best carrier

American

73.8% on time across 1,523 flights

These figures cover 2,161 flights between July 2025 and June 2026. Beyond the headline rate, 9.2% 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

Which airline is most reliable on MIA to AUS

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 MIA to AUS
Airline	Flights	On time	Avg delay	Cancelled	Grade
Frontier Airlinesthin sample	46	82.6%	97 min	0.00%	B+
American Airlines	1,523	73.8%	76 min	1.31%	C
Envoy Airthin sample	22	72.7%	47 min	0.00%	C+
Southwest Airlinesthin sample	348	69.2%	48 min	0.29%	C+
Delta Air Linesthin sample	222	69.1%	94 min	0.90%	C+

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 25 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–8am124 flights91.1%
8am–11am345 flights89.7%
11am–2pm285 flights67.8%
2pm–5pm466 flights66.5%
5pm–8pm610 flights69.3%
8pm–5am331 flights67.6%

Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 91.1% of the time, against 66.5% for the afternoon window. That is 25 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 610 flights scheduled in it.

Across the year

When delays peak on this route

This route's year swings by 13 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.September best, July worst

July is the worst month at 66.7% on time, 13 points below September, the best at 79.8%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. March was the busiest month here, with 217 flights.

Across the week, Tuesday is the strongest day at 81.4% on time and Sunday the weakest at 62.1%. 19 points is a smaller lever than departure hour, but it is free.

Delay causes

Why this route gets delayed

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 42,000 reported delay minutes.

Carrier
39%
Late-arriving aircraft
39%
National Airspace System
16%
Extreme weather
6%
Security
0%

39% 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 42,000 reported delay minutes here, that single category outweighs weather by 6 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 42,487 reported delay minutes.

The largest share of delay minutes, 39%, 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 17,000 of the 42,000 delay minutes reported here.

Cancellations sit at 1.06% against a national 1.81%, which is ordinary. Diversions add another 0.19%.

Connections and stage length

What a delay here actually costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.2% 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 1,103 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 78.5% on time across 2,161 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.

The sample behind these figures is 2,161 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. September runs 79.8% on time and July 66.7%, a swing of 13 points. If the dates move at all, move them out of July before you think about anything else. 2,134 completed flights over 12 months sit behind that.

Common questions

MIA to AUS questions

How often is MIA to AUS delayed?

Roughly one flight in four arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 27.2% of the 2,161 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.

How reliable is MIA to AUS compared with the rest of the country?

72.8% of flights arrive on time here against a national 77.6%, a difference of 5 points against it. That is worth a C on this site's grading scale.

What time of day has the fewest delays on MIA to AUS?

The 5am–8am departure window is the strongest at 91.1% on time. The 2pm–5pm window is the weakest at 66.5%, 25 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 July delays on MIA to AUS?

July is the weakest month at 66.7% on time, compared with 79.8% in September. Across the year that is 13 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. MIA to AUS and AUS to MIA 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