Airport month record

IADAPR

Washington Dulles International in April 2026

Departures: 4,843
Month: April 2026
National, same month: 79.8%
Carriers: 10

Historical statistics for April 2026, not live status or a forecast for this year’s April. For today’s conditions at IAD, see live FAA status.

IAD in April earns an A+. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 7 points better than the national rate of 79.8%. When something does go wrong the average delay runs a little over an hour. That rests on 4,843 flights, of which Republic Airways flew 437 at 89.7% on time.

Set against the rest of the country, IAD's April record is 7 points better than the US average of 79.8%. That gap is worth roughly 74 fewer late arrivals for every thousand flights.

On time

87.2%

Arrivals under 15 minutes late, of 4,819 completed departures

Avg delay

71 min

Across delayed arrivals only, not all flights

Cancelled

0.31%

Nationally in April: 0.90%

Whole year

81.1%

IAD across all twelve months

These figures cover 4,843 departures from Washington Dulles International in April 2026. On time means an arrival less than 15 minutes after the scheduled gate time, the DOT's threshold, and the national comparison uses every US departure in the same month rather than the whole year.

Against the year

April next to IAD's other months

Against IAD's own year, April ran 6 points better than the twelve-month rate of 81.1%, which makes it the best of the twelve months in the data. Cancellations were unusually low for IAD in April, at 0.31% against 1.37% across the year. Either side of it, March ran 79.6% on time and May 84.1%, so a trip moved by a few weeks would have landed in a worse stretch.

IAD month by month
Month	Flights	On time	Avg delay	Cancelled	Grade
July 2025	5,248	69.5%	102 min	2.88%	C
August 2025	5,201	81.0%	70 min	0.79%	B+
September 2025	4,815	86.8%	67 min	0.27%	A+
October 2025	4,854	84.6%	64 min	0.27%	B+
November 2025	4,589	81.8%	71 min	1.46%	B
December 2025	4,676	74.8%	69 min	0.71%	C+
January 2026	4,248	83.0%	82 min	5.65%	B−
February 2026	4,037	83.3%	74 min	1.34%	B
March 2026	4,983	79.6%	92 min	1.81%	B
April 2026 (this page)	4,843	87.2%	71 min	0.31%	A+
May 2026	5,474	84.1%	78 min	0.57%	B+
June 2026	5,053	78.1%	85 min	0.93%	B+

Departure window

The best time of day to leave IAD in April

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 13 points, against about a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am472 flights87.4%
8am–11am1,221 flights93.3%
11am–2pm850 flights87.7%
2pm–5pm318 flights86.3%
5pm–8pm1,272 flights80.8%
8pm–5am710 flights87.7%

Scale runs 70% to 100%. Rows with fewer than 30 flights show a dash.

Book the morning departure. Flights leaving between 8am–11am arrive on time 93.3% of the time, against 80.8% for the evening window. That is 13 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 1,272 flights scheduled in it.

Across the week, Tuesday is the strongest day at 90.4% on time and Wednesday the weakest at 84.1%. 6 points is a smaller lever than departure hour, but it is free.

Carrier by carrier

Which airlines ran best at IAD in April

The two carriers here are closely matched: about a point separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.

Carriers at IAD in April 2026
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	3,336	88.3%	63 min	0.06%	A+
Republic Airways	437	89.7%	64 min	0.00%	A+
Delta Air Linesthin sample	270	90.5%	75 min	1.85%	A
SkyWest Airlinesthin sample	243	85.8%	153 min	1.23%	A
American Airlinesthin sample	134	74.4%	80 min	0.75%	C+
Frontier Airlinesthin sample	126	74.0%	59 min	2.38%	C
Alaska Airlinesthin sample	96	79.2%	49 min	0.00%	B+
Southwest Airlinesthin sample	90	72.2%	57 min	0.00%	C+
PSA Airlinesthin sample	69	91.2%	271 min	1.45%	A
Allegiant Airthin sample	42	85.7%	71 min	0.00%	A+

No carrier stands out. Republic tops the table at 89.7%, about a point clear of the bottom, which is inside the range this kind of sample moves year to year.

Route by route

Busiest routes out of IAD in April

Routes from IAD in April 2026
Route	Flights	On time	Avg delay	Cancelled	Grade
IAD to ATL · Atlantathin sample	354	87.7%	62 min	1.13%	A
IAD to DEN · Denverthin sample	291	87.9%	67 min	0.00%	A+
IAD to SFO · San Franciscothin sample	229	80.8%	59 min	0.00%	B+
IAD to LAX · Los Angelesthin sample	224	80.2%	42 min	0.45%	B+
IAD to MCO · Orlandothin sample	212	91.4%	51 min	0.47%	A+
IAD to ORD · Chicagothin sample	181	75.7%	98 min	0.00%	B+
IAD to CLT · Charlottethin sample	173	91.3%	134 min	0.58%	A+
IAD to DFW · Dallas-Fort Worththin sample	152	75.5%	83 min	0.66%	B+
IAD to IAH · Houstonthin sample	146	88.4%	41 min	0.00%	A+
IAD to SEA · Seattlethin sample	128	82.7%	50 min	0.78%	B+
IAD to BOS · Bostonthin sample	120	80.8%	54 min	0.00%	B+
IAD to EWR · Newarkthin sample	120	89.2%	104 min	0.00%	A+
IAD to RDU · Raleighthin sample	113	87.6%	61 min	0.00%	A+
IAD to SAN · San Diegothin sample	110	89.1%	41 min	0.00%	A+
IAD to DTW · Detroitthin sample	110	85.5%	77 min	0.00%	A+
IAD to BDL · Hartfordthin sample	102	93.1%	43 min	0.00%	A+
IAD to TPA · Tampathin sample	100	92.9%	42 min	1.00%	A
IAD to PIT · Pittsburghthin sample	96	94.8%	20 min	0.00%	A+
IAD to PHX · Phoenixthin sample	91	89.0%	54 min	0.00%	A+
IAD to BNA · Nashvillethin sample	89	93.3%	119 min	0.00%	A+
IAD to CLE · Clevelandthin sample	86	90.7%	35 min	0.00%	A+
IAD to CMH · Columbusthin sample	85	96.5%	91 min	0.00%	A+
IAD to AUS · Austinthin sample	82	89.0%	70 min	0.00%	A+
IAD to IND · Indianapolisthin sample	82	91.5%	161 min	0.00%	A+
IAD to LAS · Las Vegasthin sample	81	95.1%	26 min	0.00%	A+

Delay causes

What held IAD up in April

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 43,000 reported delay minutes.

Carrier
38%
Late-arriving aircraft
30%
National Airspace System
30%
Extreme weather
2%
Security
0%

The largest share of delay minutes, 38%, 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 16,000 of the 43,000 delay minutes reported here. The split is drawn from 43,470 reported delay minutes.

Cancellations are rare at 0.31%, below the national 0.90% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.

Badly late arrivals are rare here: only 4.2% land an hour or more behind schedule, against 6.4% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.

What to do with this

Flying from IAD in April

For a April trip through IAD: this is one of the better months to be flying from here, 87.2% on time with 0.31% cancelled. That is a base rate for the month as a whole; a single storm can still spoil a particular day.

Washington Dulles International (IAD), the whole year
IAD in July69.5%
IAD in August81.0%
IAD in September86.8%
IAD in October84.6%
IAD in November81.8%
IAD in December74.8%
IAD in January83.0%
IAD in February83.3%
IAD in March79.6%
IAD in May84.1%
IAD in June78.1%

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