The unsung air traffic controllers

On 18 January 2024, just before 9:30 am at Shah Amanat International Airport, Chattogram, a Boeing 737 from US-Bangla Airlines requested clearance for takeoff. 

The control tower instructed the aircraft to hold its position for a brief period. However, for reasons unknown, the pilot overshot the designated holding position. 

The air traffic controller (ATC) reacted swiftly, urgently repeating: 'Maintain position, Bangla Star' (the aircraft's call sign).

The situation got complicated. A chartered plane from Arirang was already in the vicinity, preparing to land imminently. A collision between the two planes seemed imminent, risking numerous lives. 

With time rapidly slipping away, the ATC remained stoic, carefully assessing the situation. Recognising that the Arirang plane was lighter, the ATC decided it could be manoeuvred to find a way out of this crisis. 

Accordingly, the pilot was instructed to make an additional loop in the sky. Through coordinated effort, both planes narrowly averted disaster on that fateful day.

This incident echoes a similar scenario at Dhaka Airport the previous July, where a Biman Bangladesh Airlines plane veered off the runway just as another plane was poised for landing. 

The unregulated movement of aircraft without ATC guidance poses grave dangers. ATC personnel persistently guide pilots during flights, ensuring safety and order, crucially averting potential collisions through timely instructions.

Operating from glass-enclosed circular rooms at elevated heights, commonly referred to as a tower, ATC teams oversee airport operations. 

Tower heights vary across airports, with Delhi at 103 metres, Tokyo at 115 metres, and Bangkok at 132 metres. Construction of a new tower is underway at Dhaka airport, while the current active tower stands at a height of 75 feet.

Evolution of Air Traffic Control

The world's first air traffic control tower was established in 1920 at London's Croydon Airport. Standing at a mere 15 feet high, the tower was a wooden structure adorned with four windows. Its staff was tasked with maintaining flight schedules and furnishing pilots with crucial weather updates. 

Following World War I, air travel between European cities burgeoned, with Croydon accommodating a fleet of two dozen aircraft. This volume, substantial for the era, rendered Croydon the world's busiest airport at the time, prompting England's Air Ministry to introduce order to the skies, birthing the concept of air traffic control (ATC).

Heathrow Airport has since supplanted Croydon as a pivotal air hub. Presently, Heathrow's website reports approximately 1,300 daily departing flights. 

In its nascent stages, ATCs relied on rudimentary methods, such as signalling pilots with waving flags. However, technological advancements have revolutionised the field, with modern ATC systems harnessing radios, radars, and computers. 

Typically, specific towers oversee aircraft within a 25-mile radius and up to 4,000 feet of altitude before transferring control to area control centres and, ultimately, to the nearest ATC unit.

Becoming an airspace guard

In 1986, SM Ohidur Rahman earned a master's degree in physics. He began applying for positions aligned with his qualifications, a path dictated by the limited options for someone with a typical middle-class upbringing. 

One day, an announcement in The Daily Ittefaq caught his eye: the Bangladesh Civil Aviation Authority sought candidates for the role of Assistant Aerodrome Officer. 

Curious, but unfamiliar with the job's responsibilities and prerequisites, he decided to pursue it nonetheless.

A few days later, he received an invitation to participate in the job test. Finding the exam manageable, he secured the position and embarked on a six-month training program. 

During this period, he delved into the intricacies of air traffic control, learning about ATC's pivotal role, flight operations, pilot responsibilities, and communication protocols. Additionally, he acquired vital knowledge on handling emergencies such as plane crashes and hijackings.

After completing basic training, Ohidur was stationed at Dhaka Tower before being posted to Chittagong for on-the-job training. His career commenced at Chittagong Tower, where, after five to six months, he assumed the role of a solo controller.

During his tenure, Chittagong Airport was notably small, with only Biman Bangladesh Airlines operating regular flights, supplemented occasionally by Air India with 2-3 flights per week. 

The runway's short length restricted landings to aircraft such as the F27, F28, and Barajor DC 10. Ohidur remained in Chittagong until '94, with occasional short-term assignments to Saidpur or Rajshahi.

Compared to land or sea travel, air transportation sounds straightforward, due to the absence of physical barriers. Yet, complexities arise from the diverse aerial routes. 

For instance, various flight paths exist at different altitudes, leading to potential collisions if not managed properly. Consider two planes converging on the same route—one cruising at 18,000 feet and the other at 16,000 feet—a collision risk can emerge without intervention.

Moreover, when a pilot intends to descend from 16,000 feet to 14,000 feet, cooperation with ATC is essential. ATC possesses comprehensive data on aircraft movements at different altitudes, ensuring safe navigation and preventing mid-air mishaps. 

In instances where pilots lose their bearings, ATC provides invaluable guidance, leveraging radar systems to navigate them safely to their destination airports.

ATC works predominantly within controlled airspace, encompassing the airspace surrounding airports at designated altitudes, where ATC governs aircraft movements. Conversely, ATC also offers guidance beyond controlled airspace, albeit over shorter distances.

ATC staff are on duty from 7:30 am to 2:00 pm, from 2:00 pm to 8:00 pm, and for an extended 11 and a half hours shift on the third day of the week. Efficient communication between ATC and pilots is crucial, with codes such as "May Day" or "7700" conveying emergencies. 

In ATC operations, there are some other specific codes that signify situations like a hijack or radio communication failure.

ATC personnel play a critical role in assisting pilots during adverse conditions, such as reduced visibility due to fog or rain, ensuring safe landings even when visibility is reduced to zero.

"It is important for ATCs to possess multitasking abilities and patience, with numerical competence for staying ahead," said Ohidur. 

"Memorization of crucial details such as the location of airport hangars, taxiway lengths, and the count of runway lights is essential," he added. 

An alert ATC, Ohidur stressed, ensures the safety of hundreds of lives. After retirement, Ohidur is occasionally called upon to take classes for new recruits.

Navigating Air Traffic

Air traffic management is a globally coordinated effort, involving contributions from nearly every country. 

Airlines must navigate various processes to ensure the success of this initiative. This involves obtaining permission from Civil Aviation authorities and negotiating air service agreements. 

Additionally, for scheduled passenger flights, crucial information such as flight type, altitude, speed, and route must be communicated via the AFTN (Aeronautical Fixed Telecommunication Network) channel.

Flight scheduling occurs biannually, with Summer and Winter Schedules. Airlines submit their schedules to the International Air Transport Association (IATA), which consolidates and distributes them with the agreement of all involved parties.

Countries along the flight routes receive schedule updates via telex two hours before departure. Since the introduction of wireless communication in aircraft in 1930, Air Traffic Control (ATC) maintains communication with pilots via radio. Radar assistance is employed as flight volumes increase.

ATC utilises primary and secondary radar units. Primary radar detects aircraft location but not altitude or speed, while secondary radar, connected to aircraft transponders, provides detailed positional data.

"Modern technology ensures comprehensive aircraft surveillance, preventing unauthorised entry into prohibited, dangerous, or restricted airspace," said Ohidur. 

Dhaka Airport handles an average of 200 flights daily, with 350 to 400 aircraft transiting Bangladesh's airspace, each subject to fees payable to the Civil Aviation Authority.

Adherence to rules and regulations, established by the Chicago Convention of the International Civil Aviation Organization (ICAO) post-World War II, is paramount for aviation safety.

This article was originally published in Bangla and was translated by Miraz Hossain.