Even though there are no exact statistics about the actual errors made by ATCs, a significant number of them are hesitant to report their mistakes in fear of punishment. However, reporting such instances could actually help to prevent tragedies.

Almost half of ATCs experience fatigue

In 2006, a regional airliner crashed while taking off from a runway that was too short in Lexington, Kentucky. Forty-nine of the fifty people on board died. The accident was caused by an air traffic controller who had cleared the plane for takeoff, but failed to notice it turn onto the wrong runway. It was later reported that the controller had slept for only two hours before the tragedy.

“Mitigating the effects of fatigue on air traffic controllers is a major focus of the FAA. The agency’s goal is to have a well-rested controller workforce, and we are working hard to achieve that goal on many levels. The efforts include an extensive fatigue risk management initiative, which involves working closely with controllers to address fatigue-related issues and promote carefully monitored working conditions,” says Paul Takemoto, Spokesperson at The Federal Aviation Administration.

However, the problem is still far from being resolved. A recent FAA study has revealed that ATCs are still making a rather disturbing number of significant errors, such as bringing planes too close to one another due to chronic fatigue.

Basically, two-fifths of all air traffic controllers continue to suffer from chronic fatigue; in most cases that fatigue has little to no connection to poor working conditions.

“Even with eight to ten hours of recovery sleep, alertness may not recover to the full rested baseline level, but may be reset at a lower level of function,” the report said.

In 2011, two airplanes landed at Washington's Reagan National Airport without any assistance from the airport's control tower as the ATC had fallen asleep on duty.

Notwithstanding the above, exhaustion is one of the factors that sometimes are beyond human control. But there is a whole range of other aspects which can significantly compromise ATCs’ performance.  


Communication difficulties

Even though air traffic controllers are trained to use standard air traffic phraseology, unfortunately, sometimes misunderstandings still do occur. In 2008 five died after air traffic controllers had sent two planes on a collision course. The accident took place because the ATCs misunderstood that the planes would be executing a fast low flying exercise.

Phraseology may become a very serious issue due to different levels of the English language proficiency. Although English was made the mandated language of aviation back in 1951, standard phrases used by air traffic controllers and pilots are still sometimes being misunderstood due to the language barrier.

If English is not a person’s native language, he or she may fail to take into account the different structure of words, phrases and sentences. Different pronunciation is also a common issue as even such simple words as “go” and “no” can get confused due to distinct phonetic features of a certain language.

According to the International Federation of Air Traffic Controllers' Associations (IFATCA), the communication loop between pilots and controllers is a very robust process.

“One study has shown that the reliability of the communication loop is above 99%, meaning that misunderstandings occur in less than 1% of all communication,” they say.

As stated by IFATCA, in cases where misunderstandings do occur, the Air Traffic Management system is equipped with certain mechanisms to correct them. There are other controllers and pilots listening to what is being said as well as such safety measures as the traffic collision avoidance system (TCAS) and the Short Term Conflict Alert system (STCA).