For pilots, the approach into Washington DC's busiest airport and the path through its congested, confined airspace must be regimented.
Often it involves a late, low-altitude turn, while passengers get a view of several national monuments and then a safe touch down on the tarmac.
But as Flight 5342 prepared to land on Runway 33, disaster struck.
Over radio, air traffic controllers scrambled to divert other planes.
When the pilots of those aircraft responded, they had eyewitness accounts of the first fatal passenger jet crash in the United States in nearly a quarter of a century.
An aircraft takes off or lands on the main runway at Ronald Reagan Washington National Airport almost every minute for much of the day.
DCA, as the airport is known, has the busiest runway in the United States.
Civilian flights pass through the congested airspace over the United States capital, while military aircraft add to the traffic as they come and go from nearby bases.
Then there are the private flights, including those transporting the very important people who live and work in the city's most famous sandstone buildings.
Adding to the difficulty of managing everything happening in the complex airspace is the security in place for the sensitive area over the US capital.
[map]The airspace is highly regulated to protect the nation's security, in particular its VIPs working below.
But late on Wednesday night, local time, there was a critical failure and a devastating collison.
Investigators don't yet know what type of failure, but the fuselages of Flight 5342 and a US Army Black Hawk helicopter are in the Potomac River and 67 lives have been lost.
On Friday, President Donald Trump said the Black Hawk was flying higher than the 200-foot (61-metre) limit placed on helicopters near the airport. The White House said he was relaying information provided by investigators.
This aviation disaster has several factors that make it astonishing and that will cause ripple effects across the country.
It involves both the nation's civil aviation industry, the American military, and happened just kilometres from the White House.
It also places an invisible string between the nation's capital and the Kansas town 2,000 kilometres away where Flight 5342 originated.
Wichita fought for years to have a daily flight to the seat of power, now it will forever be tainted by tragedy.
For some experts, this was a disaster waiting to happen. For others, there should never have been any chance of it.
Congested airspace with 'unique' landing approach
Planes approaching DCA must navigate a precise and narrow flight path to avoid restricted airspace around the nearby White House and Pentagon.
"That turn from the eastern side along the river to turn into Runway 33 is very, very tight," said commercial pilot Rick Redfern.
A "unique" low-altitude turn over the Potomac River is required, pilot and flight instructor Kenneth Byrnes said.
However, he said it was a manoeuvre that was "very regimented" and "happens a lot, all day long".
Air traffic controllers juggle both military and civilian flights, but the aircraft aren't completely reliant on them.
Pilots are trained to look for and avoid any potential problems, Dr Byrnes told the ABC.
"You're operating in three dimensions, not two, and things are coming at you from all different angles," he said
"You have to use your eyes and scan in certain ways, depending on if it's day or night, and focus on different areas to try and identify other aircraft coming at you."
In the wake of the collision, as pilots have offered commentary on landing at DCA, one theme has emerged.
"You definitely are bringing your A-game when you fly in and out of Reagan," said former long-time commercial airline pilot Kathleen Bangs.
There have been several near misses at the airport in recent years.
That's not surprising given that during a three-year period ending in 2019 there were 88,000 helicopter flights within 48 kilometres of DCA, Reuters reported.
That included about 33,000 military and 18,000 law enforcement flights, the Government Accountability Office said in a 2021 report.
Authorities have investigated nine other accidents and incidents at DCA, two of which led to deaths, according to National Transportation Safety Board records.
Some have involved close calls between landing planes and helicopters, CNN reported.
Only the day before the crash, a flight on approach to DCA had to take action to avoid a helicopter operating near its flight path.
Retired US Army pilot Darrell Feller said he had flown the same route as the Black Hawk several times a week.
He said he had been in a similar incident years ago, and described the difficulty of maintaining sight of other aircraft against the backdrop of the city and car lights on a nearby highway.
"I was flying south down the route at night, and there was a commercial jet landing on 33 and I could not see him," Mr Feller said.
"I lost him in the city lights … you can't see them."
Secure airspace under pressure
Washington DC is a commuter town.
Professionals come and go daily, taking the Amtrak or flights out of several nearby airports.
DCA is the busiest and most central, but Dulles and Baltimore international service the city too.
Also on those flights are tourists and part of what makes Washington DC such a popular destination is also the thing that restricts how much space aircraft have to share up there.
There are layers of restricted flight zones that carpet the city, including one with a radius that extends more than 50 kilometres from the city centre. Every pilot in this zone must be in contact with air traffic control.
From there, the layers of regulation squeeze aircraft together and the job gets more complex for those controllers in the tower.
Closer in, there is a restriction with a radius of about 27 kilometres from DCA that is called the Restricted Flight Zone.
Commercial flights in and out of Ronald Reagan Washington National Airport are permitted in this zone.
Then there are the no-fly zones.
The prohibited airspace over Washington DC includes areas surrounding the White House, the National Mall and the vice-president's residence.
The only aircraft that are allowed to fly within these prohibited areas are authorised flights that are "in direct support of the US Secret Service, the Office of the President, or one of several government agencies with missions that require air support" within the city.
Allied Pilots Association spokesman Dennis Tajer told MSNBC that added to the complexity of the airspace.
"DCA is a very congested airport, it is compounded by airspace restrictions to protect our capital from threats," he said.
"DCA is a compact airspace and flying at night is a challenge there."
The no-fly zones have been in effect for about 50 years.
Ronald Reagan Washington National Airport relies on a slot system as regulated by the FAA and for years, more and more landing slots have been approved by Congress.
Local records note the federal approval for 50 additional flights in and out of DCA since 2000 came "over the strong opposition of the Airports Authority".
Too low for collision avoidance system
Aircraft do have a sophisticated traffic collision avoidance system, or TCAS, that is supposed to alert pilots to potential issues.
"It works by communicating with other aircraft," Dr Byrnes said.
"It should identify if you are on some sort of collision path with an aircraft."
However, it often does not work at low altitude.
On Wednesday night, Flight 5324 and the Black Hawk helicopter found themselves in a tragic set of circumstances.
In a busy airspace, with little room to move, low light and at an altitude too low for the safety system designed to avoid a crash to work.
Flight 5324 was on approach to the airport at about 300 feet when the collision with the Black Hawk helicopter occurred.
"There just isn't enough room below that to manoeuvre," said aviation safety expert and former airline pilot John Nance.
Investigations have started and critical flight data will help put together what exactly happened and how this could have been avoided.
"It's hard to speculate who was in the wrong position, but it seems like the [plane] was on the normal approach that they would have made to that airport," Dr Byrnes said.
He said there were likely failures of multiple systems that led to the crash.
The cockpit voice recorder and a flight data recorder from the plane have now been recovered, according to the NTSB.
They have been taken to a lab to be analysed.
Investigators are expected to have a preliminary report into the deadliest US air disaster in more than 20 years within 30 days.
"It's unbelievable how much we fly without incident," former FAA administrator Randy Babbitt told CNN.
"So when we do have one, it lights up everything."
Army Secretary nominee Daniel Driscoll said during a Senate hearing on Thursday, local time, that the crash may prompt the military to reconsider conducting training operations near the busy Washington DC airspace.
"This seems to be preventable," Mr Driscoll said.
"I think we might need to look at where is an appropriate time to take training risk, and it may not be near an airport like Reagan."
