The presidential 747 twice passed about 160 metres from the Washington Monument, near the height of its tip

Just before 21:45Z on 29 October, the new presidential 747 came up the Potomac River at low altitude. It crossed the National Mall and passed over the White House, where President Trump and the first lady were handing out Halloween candy. Two minutes later it came back the other way.

Residents had about 20 minutes of public notice. Reagan National Airport, 3 miles to the south, stopped all flights for almost half an hour. Many said the low jet over central Washington frightened them. News reports, citing flight-tracking data, said the jet flew as low as 400 feet.

That figure should not be read as height above the ground. Flight-tracking sites show the transponder's pressure altitude, which assumes standard air pressure. Corrected for the day's high pressure, the jet was about 585 feet above the White House lawn on its first pass and 535 to 570 feet on its second. Its lowest point over the city was about 530 feet, just north of the White House, where the ground is higher.

The correction also shows how close the jet came to the Washington Monument. Both times it went by on the monument's west side, about 160 to 170 metres away. On the first pass it was about 75 feet above the height of the tip; on the second, within about 45 feet of it.

Why 400 feet is not the height above the ground

Aircraft transponders report pressure altitude. That figure assumes a standard sea-level pressure of 29.92 inches of mercury. Pilots and controllers correct it with the local altimeter setting. Flight-tracking websites usually show the uncorrected figure; Flightradar24 labels it "barometric altitude".

At 21:52Z, the weather station at Reagan National Airport reported a setting of 30.15 inches. That is high pressure. It means the true altitude was about 210 feet higher than the transponder said. The warm 19C afternoon adds about another 10 feet.

With the correction applied, the jet spent about 6 minutes over the District below 1,000 feet above the ground. The only part of the flight above that line was the turn over Catholic University. There, a widely shared Flightradar24 screenshot showed 975 feet. The height above the ground was about 1,000 to 1,060 feet.

Two passes at the monument

The Washington Monument is 555 feet tall. Its tip is 595 feet above sea level, according to the FAA's obstacle database. It stands about 900 metres south of the White House, on the line the jet flew both times.

On the first pass, northbound, the jet was about 673 feet above sea level as it went by at 21:45:03Z, roughly 75 feet above the height of the tip. On the second pass, southbound at about 21:47:55Z, it was climbing through 600 to 640 feet, within about 45 feet of the tip's height.

Its position to the side is harder to pin down. Every flight-tracking position comes from multilateration, which can be off by a few hundred metres, and four receiver networks disagreed by up to 190 metres about where the jet crossed the monument's latitude. So we also measured the passes from public video, using the jet's 68-metre wingspan and the monument's own dimensions as rulers. Four videos show the first pass west of the monument, and two show the second. The clearest, from a Council of DC camera north-northeast of the monument, shows the jet passing behind the shaft.

Combining the video measurements with the flight-tracking data puts the first pass about 160 metres west of the monument, give or take about 45 metres, and the second about 170 metres west, give or take about 55. Neither pass went directly over the monument.

How low over the White House

Both passes went over or very close to the White House. On the first pass the video puts the jet over the west end of the residence or the West Colonnade, about 75 metres west of its centre, give or take about 55 metres. On the second it went almost directly over the house.

The house is 70 feet tall on its south side, so its roof is about 122 feet above sea level. On the first pass the jet was about 645 feet above sea level, roughly 525 feet above the roof. On the second pass it was 595 to 620 feet above sea level. That is about 475 to 500 feet above the roof and 440 to 465 feet above the tip of the rooftop flagpole. Above the lawn, the two passes were about 585 feet and 535 to 570 feet.

Reagan National stopped for half an hour

Reagan National Airport sits about 3 miles south of the White House, under the jet's path up and down the Potomac. While the 747 was over the city, nothing took off or landed there.

The FAA had planned for it. At 20:42Z its Command Center warned airlines of arrival delays at National of up to 30 minutes "due to VIP movement". At 20:56Z it issued a ground stop. That held DCA-bound flights at their departure airports, from Boston to Jacksonville and west to Indianapolis. The ground stop came 28 minutes before the public notice from AlertDC. A cancellation advisory issued at 21:44Z lifted it from 21:41Z.

The last departure before the flyover left at 21:25Z. The next one left at 21:52Z. The last arrival landed at 21:34Z, and the next at 22:03Z. On 27 other October evenings, those same windows held a median of 14 departures and 10 arrivals, and 24 movements in all.

Departures fell 12 flights behind a typical evening and were still 4 behind at 23:00Z. Arrivals were 12 behind at 23:00Z. The area between the curves, a rough proxy for delay, comes to about 550 aircraft-minutes for departures and 530 for arrivals by 23:00Z. It compares the evening with a typical one, not with airline schedules, and it depends on the comparison: against the four previous Thursdays it is about 600 and 400, and counting from 21:00Z instead of 21:25Z it is about 260 and 440.

What controllers and pilots said

Archived radio from LiveATC shows controllers holding traffic and explaining why. HEXBIRD transcribed the recordings by machine and checked each quote by transcribing it again with a second, larger model. Times are when each transmission starts in the recording. Words in square brackets are uncertain. Speakers are identified from context.

21:30:41ZDCA tower
Controller to United 654, waiting to depart
…you got [a] release time, but on top of that we got flyover, so expect [a delay].
21:36:14ZDCA tower
Controller to all departures
We're currently stuck on everything. All the traffic is stopped due to the flyover. Expect about 10 to 15 minutes delay.
21:36:44ZDCA ground
Controller to Envoy 4138, waiting to push back
I haven't forgotten about you, but we're stopped […] right now and I can't get you out. They're doing a flyover, so it shouldn't be too long. Hopefully another 4 or 5 minutes, but I'm not positive.
21:37:07ZDCA tower
Controller
It's a flyover, and then I'm guessing it's going to be at least 15 minutes from now on.
21:37:46ZDCA ground
Controller
And for everyone waiting, I'm being told it's going to be at least 15 minutes for the flyover.
21:38:41ZDCA tower
Controller
They're coming from 25 miles south of the DCA. They'll be flying right by our airport from Andrews.
21:40:06ZDCA ground
Probably a pilot, then the controller
Is it a flyover or VIP? I'm told it's a flyover. I don't even know what it is.
21:42:47ZDCA ground
Controller
If anyone wants to see the flyby, I'm not sure where exactly they're going, but if you look down the river there, it's a 747.
The jet was then about 11 km south of the airport, coming up the river at about 1,300 ft.
21:49:28ZDCA tower
Controller
[Attention] all departures, we're going to launch the departures shortly.
21:49:43ZDCA ground
Unidentified
How many more flybys? Hopefully that's the last.
Less than a minute after the jet's second pass by the airport. The Washington Post also reported this exchange.
21:51:51ZAndrews
The 747, callsign Freedom 01
Good evening, Freedom 01 is approximately 10 miles out for left base, visual 1 left.
The jet's call to Andrews tower as it headed back to land on runway 1L.

What the rules say

Federal aviation rules set a minimum for flights over cities. Aircraft must stay 1,000 feet above the highest obstacle within 2,000 feet of them (14 CFR 91.119). Near the monument that means 1,595 feet above sea level. The jet was about 900 to 1,000 feet below it.

Being a military aircraft does not by itself exempt the jet from this rule; FAA guidance lists it among the rules that apply to public aircraft. Flyovers like this one usually run under a waiver or other authorisation, and this flight was coordinated with air traffic control. HEXBIRD has not seen the terms of any authorisation, so the data cannot show whether the jet broke a rule. It does show that the jet flew far below the ordinary, unwaived minimum for a fixed-wing aircraft there.

Timeline

~20:24Z	4:24 p.m.	The same airframe lands at Joint Base Andrews as Air Force One, back from the Charlotte area.
~20:40Z	4:40 p.m.	President Trump tells the press pool the jet will fly over the White House.
20:42Z	4:42 p.m.	FAA Command Center warns of DCA arrival delays of up to 30 minutes "due to VIP movement".
20:56Z	4:56 p.m.	FAA issues a ground stop for DCA-bound flights, 20:45Z to 21:45Z.
21:24Z	5:24 p.m.	AlertDC posts a public notice of the flyover.
21:25Z	5:25 p.m.	Last departure from Reagan National before the flyover.
21:28Z	5:28 p.m.	First fixes after takeoff from Andrews, as FRDMM01, heading south at about 1,150 ft.
21:34Z	5:34 p.m.	Last arrival at Reagan National before the flyover.
21:44Z	5:44 p.m.	FAA cancels the DCA ground stop, effective from 21:41Z.
21:44Z	5:44 p.m.	Flies north up the Potomac over Reagan National Airport, about 820 ft above the water.
21:45:03Z	5:45 p.m.	First pass: goes by about 160 m west of the Washington Monument, about 75 ft above the height of its tip.
21:45:12Z	5:45 p.m.	Over the west end of the White House, about 585 ft above the ground.
21:46Z	5:46 p.m.	Turns over Catholic University, about 1,060 ft above the ground.
21:47:45Z	5:47 p.m.	Second pass over the White House, about 535 to 570 ft above the ground.
21:47:55Z	5:47 p.m.	Passes about 170 m west of the monument, near the height of its tip.
21:49:43Z	5:49 p.m.	On DCA ground frequency: "How many more flybys?" "Hopefully that's the last."
21:52Z	5:52 p.m.	Departures resume at Reagan National, with United 654.
21:54Z	5:54 p.m.	Last fix, on final approach to Andrews.
22:03Z	6:03 p.m.	First arrival at Reagan National since 21:34Z, American 3034.

How we did this

The jet, a Boeing 747-8 designated VC-25B (Mode S address AF83F3), broadcast no ADS-B position during the flyover. Every position here comes from multilateration (MLAT). Volunteer receivers time the jet's transponder replies and solve for its position. We used four networks that run their own receivers and solvers: adsb.lol and airplanes.live (through the HEXBIRD archive), ADS-B Exchange and Flightradar24. Together they produced about 770 fixes during the flight.

To test the networks, we compared each against a path we know: the jet's straight-in final approach to runway 1L at Andrews at 20:24Z, at the same heights as the flyover. There the jet is on the runway's extended centreline. Every network missed it by 230 to 300 metres RMS. ADS-B Exchange, adsb.lol and airplanes.live scattered around the line. Flightradar24's track was smooth but consistently about 200 metres east of it. None was clearly better, so we give each network equal weight. They report at very different rates, from every 2 to 3 seconds (Flightradar24) to every 17 (the airplanes.live live feed), so we scale each fix's weight to make every network count the same in total. This is a balancing choice, not an optimal fusion: the networks may share receivers and their errors are partly biases.

We estimated the path with a Kalman filter and Rauch-Tung-Striebel smoother: a constant-velocity model with white-noise acceleration tuned by maximum likelihood. It rejected 27 of about 770 fixes as inconsistent with the rest. From flight-tracking data alone, it puts the first pass about 115 metres west of the monument (70 to 140 across 48 smoother settings) and the second about 235 metres west (180 to 270). Each network smoothed on its own gives 20 to 210 metres and 140 to 350. On the Andrews approach the same smoother's track was off by up to about 250 metres, so flight-tracking data alone cannot rule out an overhead pass.

The video measurements came from four public videos: the White House's own video from the South Lawn, a Council of DC camera on the Wilson Building, and posts by @peggyhelman01 (South Lawn) and @STATter911 (a high-rise in Pentagon City). We located each camera from landmarks. The jet's 68.4-metre wingspan converts its apparent offset from the line to the monument into metres. The monument's known dimensions give the jet's distance relative to the monument's. Joining frames before and after the jet reached the monument's distance gives where it crossed. On the first pass this puts the jet 110 to 175 metres west of the monument (best estimate 150 to 170), and on the second 135 to 190 metres west (best 155 to 180). The Council of DC camera shows the jet passing behind the shaft, which places it on the far side of the monument from that camera, to the south-west. The video estimates assume straight flight between frames and rest on approximate camera positions. Heights from video agree with the transponder on the first pass and are less certain on the second, when the jet was banking.

To combine the two, we added the video measurements to the smoother as constraints on the jet's east-west position only, since the video clocks were not checked against UTC. We scaled the flight-tracking noise so that, without video, the track's sideways uncertainty over the city matches the Andrews test (about 150 metres, one standard deviation). The likely ranges shown are 1.645 standard deviations of the combined estimate. Neither the single runway approach nor the video ranges amount to a measured confidence level, so we call them likely ranges rather than 90% intervals.

Altitude is the transponder's Mode S pressure altitude, reported in 25 ft steps. We converted it to true altitude using the following:

the KDCA altimeter setting of 30.15 inches at 20:52Z and 21:52Z, which adds 211 ft
a temperature correction for 19C air against the standard 15C, which adds about 1.5% of the height above the station
USGS 3DEP bare-earth elevation under each fix, to get height above the ground

We use a working allowance of about 50 ft for the uncertainty. It is a judgement, not a measured bound: it covers transponder rounding, a typical altimeter error and small timing offsets, but we have no calibration for this aircraft. Altitude at each moment is interpolated between the transponder's reports, which come independently of the MLAT position.

We took the White House's height from its published dimensions (70 ft on the south side) and the rooftop flagpole from OpenStreetMap. Ground levels come from USGS 3DEP.

For the airport comparison, we estimated the takeoffs and landings at Reagan National between 20:00Z and 23:00Z on each day in October from ADS-B. We counted fixed-wing aircraft within 3.5 km of the runways that climbed or descended at least 300 ft from runway level. This does not check runway alignment or touchdown, so treat the counts as estimates. 16 October was left out because its data was too sparse. Ground stop details come from the FAA Command Center's public advisory archive.

Radio quotes come from LiveATC archives of the DCA tower and ground frequencies and an Andrews feed. We transcribed them with Whisper large-v3-turbo and checked each quote again with large-v3.

We did not have access to the jet's own flight data, the FAA's radar data or any waiver. News reports supplied the public notice times. Detailed views of the flight-tracking fixes, each network's estimates and the video analysis follow below.

Sources: airplanes.live replay of the flight, Washington Post report on the flyover, The Independent report on the flyover, Flightradar24 screenshot posted on Bluesky, Iowa Environmental Mesonet METAR archive, FAA ground stop advisory 067 for DCA, LiveATC archives for Reagan National, White House video of the first pass, Council of DC camera video, @peggyhelman01 video of the second pass, @STATter911 video of both passes, 14 CFR 91.119 minimum safe altitudes.

Detailed views

These views show the sources behind the main graphics: every flight-tracking fix, the track from flight-tracking data alone, each network's own estimate at the monument and the White House, and the video analysis.