Global Aircraft Tracking: The Issues

qz1The growing frustration with the speed of industry efforts to implement better aircraft tracking is understandable.
2014 will go down as the year that threw the spotlight on the industry’s weak spot: how to locate a missing aircraft flying over oceanic airspace, polar routes or remote terrain – all out of the range of radar.
While an instantaneous data flow may not necessarily save lives, knowing precisely where an aircraft foundered could help speed search-and-rescue operations, avoid the huge cost of searches for both survivors and the all-important black boxes that contain the crucial information about what went wrong, and why.
2015 should in fact see some progress, however. An industry commitment made after the disappearance in March 2013 of the missing Malaysia Airlines Flight 370 should kick start the implementation of a near-term bag of quick fixes that build on existing technologies already on board – essentially implementing the least costly and time-consuming upgrades to bring the least equipped airline up to scratch.
That will precede a longer term strategy which UN aviation agency ICAO is heading which will develop a GADSS – or Global Aeronautical Distress and Safety System – which will go far beyond that the recently agreed basic performance criteria. Its ambition will take some time to develop but at its core is a universal tracking service and autonomous distress tracking.
Space ADS-B

This year will also see the launch of the first Iridium NEXT satellite which will carry an Aireon receiver. As more NEXT satellites become operational these receivers will send air traffic control Automatic Dependent Surveillance – Broadcast (ADS-B) tracking data from aircraft flying beyond the range of ground – based surveillance.
Scheduled for a 2017 completion, Aireon is set to revolutionise the way air traffic control agencies around the world manage aircraft as, in principal at least, there will be near-real-time situational awareness. An Aireon-type service could well provide the backbone of ICAO’s GADSS vision.
Existing technology to track aircraft operating out of radar range is all based on satellite technology in some way or another but as the IATA-led Aircraft Tracking Task Force pointed out, in terms of tracking capabilities, “the picture is not as complete as had originally been anticipated”.
While aircraft flying through busy continental airspace are closely tracked by radar and other systems, crews often simply report in from remote or oceanic areas via HF radio. And although many aircraft transmit their location via Automatic Dependent Surveillance – Contract (ADS-C) technology or an Aircraft Communications Addressing and Reporting System (ACARS), many aircraft are not equipped with either, the task force found.
Some argue that the vulnerability of proposed future aircraft tracking and data streaming solutions in distress situations is their dependency on the aircraft’s satellite broadband technology because the new and emerging broadband links require more accurate antenna steering in order to achieve higher bandwidth. Outside normal flight conditions, the satellite broadband link can however be easily breached should the aircraft stall and lose control.
Vulnerable
Interestingly, the current classic Inmarsat and Iridium services are less dependent on accurate antenna steering so they are actually less vulnerable than the new broadband links.
“The most vulnerable tracking systems are those that use satellites and require an antenna fixed to the aircraft to be pointed toward the satellite,” says one expert who cites the 2009 Air France Flight 447 tragedy where aircraft performance information was streaming in near-real-time over ACARS to Air France’s operational centre. “The AF447 flight did send out some ACARS messages when systems started to break down but the satcom probably stopped working when the aircraft started falling.”
He believes this is where space-based ADS-B tracking looks likely to come into its own because as long as an aircraft’s transponder with ADS-B capability continues working there is arguably no better source of position information. This is due to the transponder broadcasting the position once per second and in a fast developing accident situation the reporting has to be in the second range not in the minute range which is sufficient in regular flight.
“The other advantage of a transponder-based solution is that transmissions would not be lost when the aircraft becomes unstable because the transponder uses an omni directional antenna while most satellite broadband systems use an antenna that needs to be steered towards a satellite, which when the aircraft becomes unstable is very hard to maintain.”
Altitude
If an ADS-B transponder is the best means of sending position data that leaves the question of how to ensure transmissions are picked up for as long as possible at low altitudes over the sea or while flying through other challenging environments.
AirNav, the Indonesian air navigation service provider, has deployed ADS-B ground stations at the nation’s 27 biggest airports including some remote ones so they would be unlikely to be able to deploy more stations closer to where the AirAsia aircraft probably stopped losing altitude as the aircraft would have started going out of the range of ground-based surveillance.
Don Thoma, Aireon’s chief executive, tells Air Traffic Management that as long as the transponder is on and broadcasting, Aireon should be able to ‘see’ to the ground. “Even in situations where there are mountains that may block the line of sight between the airplane and the satellite, the satellites are low earth orbiting – meaning they move across the sky from horizon to horizon in 8-10 minutes – so the signals will be received even from aircraft on the ground in mountainous terrain.”
Thoma adds that once it is in service, Aireon will receive ADS-B messages from 1090 MHz equipped transponders in real-time. “So during a distress phase Aireon will be receiving location and velocity updates from an aircraft every 1-15 seconds with a majority about every second. So we will get very accurate and timely information from the aircraft,” he says.
Compelling
Because most airlines around the world are already required to equip with ADS-B transponder technology by 2020, Aireon offers a compelling proposition as operators need make no additional investment.  “As for the air navigation service providers, either they will be customers of Aireon and have a real-time data feed for their airspace or if they are not a customer they will have access to the Aireon ALERT (Aircraft Locating and Emergency Response Tracking) service for free,” adds Thoma.
If Aireon delivers and if no other system is developed to be as effective at picking up signals from aircraft at low altitude over the sea there will arguably not be much incentive to deploy a rival system.
Aireon could however face more competition over land from ADS-B stations on the ground as the flight tracking website operators such as FlightRadar24 tempt more people to put cheap receivers on the roof of their houses. Even so, in remote areas like Borneo, Aireon will arguably remain a more pragmatic solution.
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