Washington Dulles International in December 2024

80.3%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 2024, reporting carriers scheduled 4,479 domestic departures from Washington Dulles International (IAD). 80.3% left less than 15 minutes late and 80.1% reached their destination on time; 0.3% were cancelled.

Nationally that month, 77.8% of flights departed on time and 78.1% arrived on time, so IAD departures were 2.5 points above the national departure figure.

A year earlier, in December 2023, the airport had 3,980 departures with 86.7% leaving on time: a change of −6.4 points, with flights up 13%.

Flights arriving at IAD that month were on time 80.9% of the time (4,478 scheduled arrivals).

Of the delay minutes that carriers assigned to a BTS cause category that month, late-arriving aircraft 40%, air carrier 37% and national aviation system 19%.

On time 80.1%
Arrived 15+ minutes late 19.2%
Cancelled 0.3%
Diverted 0.3%

Every scheduled departure from IAD in December 2024, judged by arrival at the destination.

December 2024 against a year earlier, the airport's year and the nation

Measure	Dec 2024	Dec 2023	IAD, 12 months to Jul 2026	All reported flights, Dec 2024
Departed on time	80.3%	86.7%	82.6%	77.8%
Arrived on time	80.1%	88.1%	80.1%	78.1%
Cancelled	0.3%	0.3%	1.4%	0.7%
Average departure delay (late minutes only)	15.2 min	9.8 min	14.7 min	16.6 min
Scheduled departures a day	149	133	159	19,686
Scheduled departures	4,479	3,980	58,031	590,581

Airlines that month

Reporting carrier	Flights	Share	On time	Avg arrival delay	Cancelled
UA United Airlines	2,743	61%	80.3%	3.8 min	0.3%
YX Republic Airline	664	15%	82.7%	2.4 min	0.2%
DL Delta Air Lines	251	6%	81.7%	1.1 min	0.0%
OO SkyWest Airlines	250	6%	74.0%	30.4 min	0.4%
AS Alaska Airlines	147	3%	77.6%	-0.3 min	0.7%
OH PSA Airlines	143	3%	80.4%	2.7 min	0.0%
WN Southwest Airlines	103	2%	88.3%	-2.8 min	0.0%
F9 Frontier Airlines	69	2%	69.6%	21.5 min	0.0%
AA American Airlines	60	1%	73.3%	10.1 min	1.7%
G4 Allegiant Air	25	1%	56.0%	60.5 min	4.0%
9E Endeavor Air	24	1%	83.3%	12.4 min	0.0%

Busiest routes that month

Route	Cities	Flights	On time	Avg arrival delay	Cancelled
IAD–ATL	Washington to Atlanta	308	78.9%	3.7 min	0.0%
IAD–DEN	Washington to Denver	273	87.2%	-2.2 min	1.1%
IAD–SFO	Washington to San Francisco	260	78.5%	0.2 min	0.4%
IAD–LAX	Washington to Los Angeles	230	79.6%	1.1 min	0.0%
IAD–CLT	Washington to Charlotte	178	80.3%	1.9 min	0.0%
IAD–MCO	Washington to Orlando	164	76.2%	13.3 min	1.2%
IAD–IAH	Washington to Houston	138	73.9%	8.4 min	0.7%
IAD–SEA	Washington to Seattle	135	82.2%	-6.4 min	0.7%
IAD–DFW	Washington to Dallas/Fort Worth	132	79.5%	5.3 min	0.8%
IAD–ORD	Washington to Chicago	128	80.5%	5.3 min	0.0%
IAD–BOS	Washington to Boston	124	81.5%	12.6 min	0.8%
IAD–PHX	Washington to Phoenix	124	87.9%	-5.7 min	0.0%

By scheduled departure hour

100

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

Share of departures that left less than 15 minutes late, by scheduled hour (local time), December 2024.

Delay causes

BTS cause category	Share of delay minutes	National, Dec 2024	Minutes
Air carrier	37.0%	34.3%	22,621
Late-arriving aircraft	39.6%	40.2%	24,187
National Aviation System	19.1%	17.8%	11,657
Extreme weather	4.3%	7.5%	2,622
Security	0.1%	0.2%	36

61,123 delay minutes on 862 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 2024?

80.3% of 4,479 scheduled domestic departures left less than 15 minutes late, and 80.1% reached their destination on time. The national figures that month were 77.8% and 78.1%.

How does that compare with a year earlier?

In December 2023, 86.7% of 3,980 departures left on time and 0.3% were cancelled, against 80.3% and 0.3% in December 2024.

Provenance

Source: Bureau of Transportation Statistics, Reporting Carrier On-Time Performance, file for December 2024; 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.