Washington Dulles International in December 2025

77.9%departed on time

BTS: A flight is counted as on time if it arrived less than 15 minutes after its scheduled time. Only carriers with at least 0.5 percent of domestic scheduled passenger revenue report.

In December 2025, reporting carriers scheduled 4,676 domestic departures from Washington Dulles International (IAD). 77.9% left less than 15 minutes late and 74.0% reached their destination on time; 0.7% were cancelled.

Nationally that month, 72.0% of flights departed on time and 71.9% arrived on time, so IAD departures were 5.9 points above the national departure figure.

A year earlier, in December 2024, the airport had 4,479 departures with 80.3% leaving on time: a change of −2.4 points, with flights up 4%.

Flights arriving at IAD that month were on time 79.1% of the time (4,649 scheduled arrivals).

Of the delay minutes that carriers assigned to a BTS cause category that month, late-arriving aircraft 35%, air carrier 32% and national aviation system 29%.

On time 74.0%
Arrived 15+ minutes late 25.0%
Cancelled 0.7%
Diverted 0.3%

Every scheduled departure from IAD in December 2025, judged by arrival at the destination.

December 2025 against a year earlier, the airport's year and the nation

Measure	Dec 2025	Dec 2024	IAD, 12 months to Jul 2026	All reported flights, Dec 2025
Departed on time	77.9%	80.3%	82.6%	72.0%
Arrived on time	74.0%	80.1%	80.1%	71.9%
Cancelled	0.7%	0.3%	1.4%	1.5%
Average departure delay (late minutes only)	17.4 min	15.2 min	14.7 min	21.2 min
Scheduled departures a day	156	149	159	19,410
Scheduled departures	4,676	4,479	58,031	582,304

Airlines that month

Reporting carrier	Flights	Share	On time	Avg arrival delay	Cancelled
UA United Airlines	2,867	61%	78.1%	5.8 min	0.1%
YX Republic Airline	852	18%	72.4%	10.2 min	1.3%
DL Delta Air Lines	243	5%	66.3%	15.3 min	3.3%
OO SkyWest Airlines	167	4%	59.3%	58.3 min	5.4%
F9 Frontier Airlines	121	3%	63.6%	21.2 min	0.8%
WN Southwest Airlines	104	2%	65.4%	15.8 min	1.0%
AA American Airlines	97	2%	71.1%	13.4 min	0.0%
OH PSA Airlines	89	2%	69.7%	11.5 min	0.0%
AS Alaska Airlines	82	2%	39.0%	21.0 min	0.0%
G4 Allegiant Air	54	1%	68.5%	19.9 min	0.0%

Busiest routes that month

Route	Cities	Flights	On time	Avg arrival delay	Cancelled
IAD–ATL	Washington to Atlanta	321	69.5%	14.7 min	2.5%
IAD–DEN	Washington to Denver	304	76.3%	10.8 min	0.3%
IAD–SFO	Washington to San Francisco	245	68.6%	19.5 min	0.0%
IAD–LAX	Washington to Los Angeles	215	85.1%	-4.0 min	0.9%
IAD–CLT	Washington to Charlotte	177	68.9%	13.6 min	0.0%
IAD–MCO	Washington to Orlando	172	76.7%	3.9 min	0.0%
IAD–ORD	Washington to Chicago	146	75.3%	10.9 min	0.0%
IAD–IAH	Washington to Houston	139	77.7%	1.1 min	0.0%
IAD–DFW	Washington to Dallas/Fort Worth	138	69.6%	8.6 min	0.0%
IAD–EWR	Washington to Newark	125	75.2%	13.3 min	0.0%
IAD–SEA	Washington to Seattle	124	47.6%	22.3 min	0.8%
IAD–BOS	Washington to Boston	122	76.2%	7.8 min	0.0%

By scheduled departure hour

On-time share:under 62%6270768288% and over

Share of departures that left less than 15 minutes late, by scheduled hour (local time), December 2025.

Delay causes

BTS cause category	Share of delay minutes	National, Dec 2025	Minutes
Air carrier	31.8%	33.3%	25,711
Late-arriving aircraft	35.0%	41.1%	28,282
National Aviation System	28.8%	19.1%	23,306
Extreme weather	4.4%	6.4%	3,574
Security	0.0%	0.2%	10

80,883 delay minutes on 1,168 flights that arrived 15 or more minutes late and carried a cause report. Carriers assign the categories; see what each category means.

Questions and answers

How many flights left IAD on time in December 2025?

77.9% of 4,676 scheduled domestic departures left less than 15 minutes late, and 74.0% reached their destination on time. The national figures that month were 72.0% and 71.9%.

How does that compare with a year earlier?

In December 2024, 80.3% of 4,479 departures left on time and 0.3% were cancelled, against 77.9% and 0.7% in December 2025.

Provenance

Source: Bureau of Transportation Statistics, Reporting Carrier On-Time Performance, file for December 2025; public domain. Domestic scheduled flights by reporting carriers, totals and averages only. The site's data runs through July 2026. Full record for IAD · methodology · corrections.