It is not a job for the faint-hearted. The training takes 3½ to four years, with one in four dropping out. And even if one makes it, the work itself is stressful.
But despite being glued to monitors for nine hours a day - with half-hour breaks in between - Mr Anthony Ang, one of 390 air traffic controllers at the Civil Aviation Authority of Singapore (CAAS), takes satisfaction from guiding pilots safely from take-off to landing.
Getting into the control chair, though, is not easy.
It starts with a three-hour aptitude test and two rounds of interviews, Mr Ang told The Straits Times at the Singapore Air Traffic Control Centre near Changi Village on Tuesday.
"It's very intense. They stress you out and drain you mentally with numbers and tests."
Mr Ang, 39, tried twice to be an air traffic controller. In 2003, he passed the test but failed to get past the first interview.
Three years later, he gave it another go and made it - though his reward was some of the most intense training he has experienced.
"The first three months were hectic with intensive lessons and about 15 written exams," he said.
"For some papers, the passing mark was as high as 85 per cent, and 70 per cent for other papers. Halfway through, I asked what I had got myself into."
But he persevered and completed the course which also includes on-the-job training and simulator sessions.
"It is a long and tough process but critical for the work that we do. Of utmost priority is the safety of persons on board the aircraft," said Mr Ang, who has been on the job for 10 years.
With the number of flights at Changi Airport expected to double in the next 10 years, the CAAS intends to grow the pool of air traffic controllers to about 600 by the end of the decade.
Based on air traffic projections and aircraft orders, the International Civil Aviation Organisation - the United Nations' civil aviation arm - estimates that the world will need another 40,000 air traffic controllers by 2030.
Singapore's air traffic controllers, who are usually based at either the Changi Airport control tower or the air traffic control centre, manage the Singapore flight information region, which is more than 1,000 times bigger than the Republic's own airspace. It includes areas in Riau - including parts of Batam and Bintan.
Handling up to 11 or 12 flights at any one time is demanding and requires focus, the ability to multitask and make decisions under immense pressure, Mr Ang said.
"Emotional stability is critical. When you step into the tower or the control room, your mind must be absolutely clear," said the father of an 11-year-old boy and a girl aged seven.
For Mr Ang, a hot beverage 15 minutes before his nine-hour shift starts helps him to be focused.
"The moment I sit in my chair and plug in, it's 100 per cent concentration," he said.
Whether it is dealing with bad weather or communication issues with pilots who may not be very proficient in English, every shift has different challenges, Mr Ang said.
His toughest was on Nov 4, 2010, when a Qantas Airbus A380 aircraft made an emergency landing at Changi Airport after one of its four engines exploded in mid-air.
Mr Ang, who was in the Changi Airport control tower at the time, said: "There was no panic but we were prepared for a pressure cooker situation with one runway down for a few hours, which meant all flights in and out had to be handled with just one runway. At the end of my shift that day, I was completely drained out.
"But there is no other job I would rather do," Mr Ang said.
