After two planes flew into New York's World Trade Centre on 9/11, the Federal Aviation Administration (FAA) grounded all flights except one, which managed to save a man's life.
The first plane struck the skyscraper shortly before 9am on 11 September 2001, followed by the second little more than 15 minutes later.
At 9.45am, another plane circled over downtown Washington, D.C. before crashing into the Pentagon building.
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The horror of the situation prompted the FAA to quickly issue a ground stop to all air traffic set to encounter New York airspace which had not yet departed, and by 10am the FAA Command Center had decided to close all US airspace.
All commercial air traffic was grounded within a few hours of the attack.
However, the FAA made an exception later the same day when snake handler Lawrence Van Sertima was bitten by one of the most deadly snakes in the world, a Taipan snake.
With the stop on air traffic preventing Van Sertima from being taken to hospital by helicopter, it took 40 minutes for him to travel to Miami’s Baptist Hospital.
Within hours he was in critical condition, bleeding from his eyes and mouth as the snake's venom attacked his blood, muscles, kidneys and heart.
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The snake bite unit of Miami-Dade’s Fire Rescue had five vials of a polyvalent antivenin, which just about helped to keep the snake handler alive, but he was in desperate need of the monovalent antivenom, which was made specifically from the venom of the Taipan snake.
The antivenom only existed in New York and San Diego, meaning it would have to be flown to Miami from one of those areas. Knowing they would be unlikely to receive clearance for a plane to take off from New York, the medics attempted to get the antivenom from San Diego.
The FAA in Washington granted permission for the flight, with the stipulation that it be escorted by two fighter jets.
Thankfully the plane made it in time, and within 45 minutes of landing the antivenom was being administered. Van Sertima recovered from the bite before finally learning about the terrorist attacks a few days after they took place.
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US airspace remained closed for several days after the attacks, but eventually the country's airports reopened and residents began taking steps to recover from the tragedy in which almost 3,000 people lost their lives.
Emily Brown