DIGITAL ATC Towers

AIBM

April - June 2018

In a bid to reduce costs without compromising on safety, the AAI has decided to implement the Remote Virtual Tower, especially in regional airports as an alternative to the traditional Air Traffic Control Tower, which consume more money and manpower.

Upon walking into any airport, a symbolic image that strikes a familiar picture is the Air Traffic Control Tower (ATCT), which enables the air-traffic controllers to control the flow of air traffic by providing them an advantageous view atop the lofty infrastructural set-up. From here, they can monitor flights taking off, landing and taxing to and from terminals.

The ATCT is a mandatory aeronautical facility for the operation of the airports and is operated by the Airports Authority of India (AAI). ATCTs are established to provide for a safe, orderly and fast flow of traffic in the airport and its vicinity.

Problem Detection

The role and importance of ATCTs is undeniable when it comes to air traffic management and navigation. However, the construction, maintenance and operational cost of ATCTs is huge and not feasible for regional or small airports where flight activity is limited or few. Here are two instances for better understanding:

In 2017, New Delhi constructed a new ATC tower, which at 101.9 metres is believed to be the country’s tallest. The tower will give a 360-degree view of the airport to the controllers who will be able to see all the three runways, aprons and taxiways. The construction of the seventh tallest ATC tower in the world took place next to the existing tower and was built at a cost of INR 3.5 billion.

The Chhatrapati Shivaji International Airport in Mumbai is equipped with an 83.8 metre high ATC tower, which also couples as a tourist landmark. The ATCT has a commanding view of most ground operations, inbound and outbound flights, thereby improving safety, efficiency and security. Since the airport and its related functions remain in fragmented parcels spread over a sizeable geographic area from Terminal 1 on the west to Terminal 2 on the east, the ATCT signifies a landmark that visually ties all of these assorted facilities together into one unified airport environment.

However, the construction and implementation process of the new ATC tower was not easy. Various complex problems arose during the implementation process, ranging from use of specialised concrete, shuttering arrangement to unique glazing challenges due to the distinctive shape of ATC tower. It involved labour strength of about 400 in peak periods to 170 in periods of not so favourable weather conditions. The project cost neared INR 1 billion.

The above two examples shed light on the difficulties and cost involved to set up an ATC tower in an airport. However, Delhi and Mumbai have two of the busiest airports in the country and also act as gateways to other countries via flights. As such, these airports can easily sustain the operational and set-up costs of newer ATC towers in addition to existing ones. The smaller and regional airports, which do not have the same means, may face a roadblock owing to the set up of ATC towers.

Seeking Solution

The traditional ATC towers can be alternated with Remote Virtual Towers (RVTs) or digital ATC towers. In simpler words, Remote Virtual Towers operate without an ATC tower and depend on technology like high resolution, infrared cameras for air traffic management.

As the name suggests, RVTs make use of remote centres to look after flights. These centres are housed in ordinary low-rise buildings, some of which may be hundreds of kilometres away. The centres receive a live video feed from cameras positioned around the airfield to create a ‘virtual’ image of the airport to be displayed on large screens positioned around the controllers’ desks.

The Remote Control Tower (RCT) or Remote Virtual Tower allow airports to improve their profitability by offering longer opening hours and preventing them from being closed down due to overbearing costs of operating traditional ATC towers.

Exploring RCTs

RCT is a fairly new concept wherein the Air Traffic Service (ATS) at an airport is performed somewhere else than in the local control tower by using technology. RCT replaces the onsite view of the airport control tower with a visualisation system located at a remote site by using high resolution visual/ infrared cameras, optimised for wide-range coverage by providing a video presentation that uses object detection and alerting functions together with information enhancement. Operating a tower remotely opens a wide range of synergies, since it allows co-location of several towers to one Remote Tower Centre (RTC), where several airports are controlled centrally by the same staff, allowing judicious utilisation of resources.

The Single European Sky ATM Research (SESAR) programme pioneered the technology of the RCT and coined the term “Remote Virtual Tower” for a remote control tower. SESAR explains, “A remote virtual tower is where ATS is remotely provided through direct visual capture and visual reproduction (e.g. with cameras). The ATS are provided using a Remote Tower Module (RTM), which includes operator workstation(s), ATM systems and display solutions. A remote tower module is the term for the complete module, including both the Controller Working Positions (CWPs) and the visual reproduction display screens.”

There are three different operational types of RCTs:

• Single remote control tower
• Multiple remote control tower
• Contingency remote control tower

Safety Quotient

Air traffic is growing exponentially in India, which increases need of Air Navigation Service Providers (ANSPs) to reduce operating costs of Air Navigation Services especially for medium and small airports using latest technology. Modernisation of Air Traffic Services requires new age technology and supporting infrastructure, which is expensive. ANSPs, for instance, constitute a fixed cost that is difficult to recover at airports with lower air movements. Even a fully equipped and operational control tower at a small airport servicing only a handful of take-offs and landings per day can be an economic burden, which may overstretch the financial capabilities of ANSPs at a lowtraffic airport. A suitable alternative is the remote tower module that is economically feasible without compromising efficiency.

However, the technology, which is already in use in countries like Australia, Canada, Ireland and Sweden, lacks global regulation from International Civil Aviation Organization (ICAO), the UN body that oversees the principles and techniques of international air navigation. The safety of the remote tower module also depends on equipment reliability and its maintenance, failing which it may negatively affect the efficiency of the module. Additionally, Air Traffic Controllers need to be trained and certified to be familiar with the use of Remote Virtual Towers for air traffic management.

Benefits of RCT

RCTs allow higher situation awareness especially in low visibility conditions using visual enhancements. This makes it more flexible when compared to traditional ATC towers. However, in order to enjoy this flexibility, one has to comply with licensed, high-end equipments that have been already tested in similar situations.

Since most of the processes are digitalised, RCTs also enable better allocation of precious human resources, in addition to allowing higher level of standardisation and interoperability across remote aerodrome systems and procedures.

The installation and commissioning process of RCTs is also faster as opposed to the traditional concrete structure as were experienced during the construction of the new ATC tower at the international airport in Mumbai. Furthermore, augmentation of situation awareness of airport and airspace is economical.

The Next Step

The AAI is working with India’s aviation safety supervisor, the Directorate General of Civil Aviation (DGCA), on the study of remote tower module and has sought information from countries where remote towers are already in use.

“Remote ATC is all the more needed for India given our vast area, low traffic at regional airports and the need to keep airfares low. However, in several parts of India availability of reliable power and telecom connectivity is a challenge,” Amber Dubey, India head of aerospace and defence at consultancy KPMG told international news agency, Reuters.

Recently, the ATC towers at two of the biggest and busiest airports – Delhi and Mumbai faced power failures, although no accidents were reported. While this highlights the importance of an alternative system such as RCT, air traffic controllers have big concerns regarding the transfer of data from the airport to the remote tower. An ATC official at India’s airport regulator told Reuters that they are yet to understand how the data transfer will work, what medium will be used and what the backup will be. “If the (data transfer) medium goes blank, the airport will be cut off,” said the official.

AAI Chairman, Guruprasad Mohapatra stated earlier in the year that India is likely to get its first remote air traffic control tower by December 2018 at Ahmedabad airport, allowing one tower to manage aircraft movements for several nearby airstrips. Mohapatra said that the concept will be useful for smaller airports under the government’s regional connectivity scheme (RCS), which aims to utilise underserved and unserved airports and improve connectivity to Tier-II and Tier-III cities.

“Under RCS, we will have a plethora of airports with just one or two flights per day. So, rather than setting up Air Traffic Control towers and deploying ATC personnel (at each of these airports) we hope to cover them with remote tower concept,” Mohapatra said. This, he stated, will be a pilot project that will pave the path towards implementation of the module across other smaller airports.

Constraints of Remote Air Traffic Control Tower

• Removing the controller from the aerodrome control tower eliminates the use of out-the-window view to visually survey the airport and its vicinity
• Reliability of dedicated data communication network, specially at remote sites
• The impact of hardware failures might be fatal for operations
• Cyber-security has become an increasing source of concern within the aviation community and remote tower operations have the potential to increase the vulnerabilities of the system
• Traffic separation, especially for VFR flights