Despite the air industry's abiding reputation as the safest form of travel, the fact remains that passengers on commercial flights are entirely entrusting their safety to the experience of pilots, air traffic controllers and ground handling staff, as well as the safety and reliability of a range of technologies.
This trust is not limited to the time that an aircraft spends in the sky. The taxiways and runways of an airport's aerodrome are a much more common setting for safety problems and incidents of this type still occur with reasonable regularity.
Although no passengers were injured when a Purolator flight overshot the runway at St John's International Airport in the Canadian province of Newfoundland and Labrador in July 2011, last year's tragic runway overrun in Mangalore or the deadly fire that broke out on British Airtours flight 28M in 1985 prove incidents during take-off and landing can be just as devastating as those which occur mid-flight.
Here we look at the safety challenges facing airfield operations managers and air traffic control (ATC) staff, from runway incursions and excursions to foreign object debris (FOD), as well as the technologies that help prevent airfield incidents from occurring in the first place.
The principal risks on runways are generally separated into three broad categories. The most common of these is the runway excursion, which is broadly defined by the ICAO as "a veer off or overrun off the runway surface".
This can cover planes exiting the runway incorrectly or veering off the side of the runway upon take-off, or when a plane, due to poor visibility, pilot miscalculation or technical issues, runs out of runway upon landing, as was the case in St John's Airport and Air India instances described above.
A runway incursion, meanwhile, is defined as a person or vehicle (including another plane) that is incorrectly present on a runway surface that presents a risk of collision, a notable example being the near-miss at San Francisco International Airport in 2007, when a SkyWest aircraft almost collided with another plane after being instructed to land on the wrong runway. A separate but related danger is the presence of FOD on the runway, which can pose serious risks to planes either landing or taking off.
The third category is runway confusion, which generally involves a plane using the wrong runway or taxiway at an aerodrome, which poses a collision risk and a danger of taking off from an inappropriate runway.
The latter is exactly what happened at Blue Grass Airport, Kentucky, in 2006, when Comair flight 191 incorrectly attempted to take off from a runway that was too short, causing it to overrun and crash, killing all onboard except for the flight's first officer.
The relatively regular occurrence of runway incidents has meant that improving runway safety has been a consistently high-profile endeavour for the aviation industry and its regulators. A June 2011 safety paper by the UK's main air navigation service provider NATS (National Air Traffic Service) cited ground safety as a significant priority, noting the importance of providing aerodromes with "technology-based safety nets designed to mitigate errors made by pilots, drivers and ATC". This focus on technology to improve safety on the ground is echoed across numerous aviation safety organisations worldwide.
As a result, a host of technologies to help prevent runway and airfield incidents are now on the market. Communications technology, for example, is a fundamental method of improving safety, one that lies beneath all other technologies in that it simply improves the speed and efficiency of reporting and ensures that safety-critical messages get through to the right people.
But significantly more sophisticated systems exist to integrate runway safety communications, allowing for faster on-the-fly decision-making as well as streamlining the reporting process.
In March 2010, UK-based IT services company Polymorph was awarded a contract by Manchester Airport's Airfield Operations team to provide a tailored safety management information system.
The technology automates safety and incident reporting, auto-populating and organising safety reports, as well as keeping track of improvements and corrections made to equipment and protocol. The system also automatically ensures all national and international civil aviation safety regulations are being upheld.
This leaves ATC staff, managers and others to concentrate on communicating with one another rather than getting bogged down in data entry.
"The new system Polymorph developed for us provides a central repository that captures all incident data," said Manchester Airport's airfield operation manager Radford Taylor. "This can now be accessed by a wider range of employees therefore ensuring that suggestions about safety can be captured in a structured manner which delivers improvement."
Layered on top of a high-quality communications set-up should be a number of well-integrated physical technologies that makes the safest option the simplest option for pilots and their ATC colleagues.
Sensor systems play a major role in runway safety, especially where FOD detection is concerned. Qinetiq's Tarsier system, operational from Heathrow and Vancouver to Dubai and Doha, uses radar technology to continuously sweep runway surfaces for any object that might pose a risk to departing or arriving flights.
"BAA carries out four runway inspections a day," said Heathrow's head of airside operations Colin Wood. "Tarsier does a sweep every 68 seconds. There has been FOD detected by the radar which would not normally have been picked up due to the frequency of the runs we normally carry out."
Cameras support the system in identifying whether or not spotted FOD threatens planes and Tarsier's new iterations include a day and night camera to help make those decisions, even in the dark. Brett Patterson, airside operations director at Vancouver Airport, the first airport to install day / night cameras to its existing Tarsier system, praised the reassurance the cameras have brought with them. "The camera allows us to determine quickly whether the FOD is a two inch worm that poses no threat, or a broken zipper from a suitcase that does," he said.
Lighting the way for pilots
The introduction of runway status lights is also improving airside safety at airports worldwide. These innovative lights allow ATC to provide clear visual messages to pilots moving on to incorrect runways or taxiways, flashing red to warn that a plane is not cleared to cross or move down a particular route.
Last year a set of runway status lights successfully completed a test period at Boston's Logan International Airport, having already been deployed at major US airports in Dallas, Los Angeles and San Diego.
Clearly, lights like these have the potential to save lives in a situation similar to Comair 191's tragic disaster in 2006. Fortunately, in 2011 the Federal Aviation Administration (FAA) kicked off an initiative to install runway status lights at a further 23 airports across the US, from McCarran Airport in Nevada to JFK in New York.
"These lights are designed with the pilot in mind," said FAA's acting administrator on the launch of the national initiative. "It's a big step for safety on the runway. We're expecting to see positive results right from the start."
These "positive results" might be difficult to quantify, as it's impossible to know if individual incidents would have become more serious without the support of safety technologies. It's clear these systems and others, including GPS tracking for airfield vehicles and engineered materials arrestor systems (EMAS) to help decelerate aircraft that have overrun, have proved their worth to passenger safety.
This is supported by FAA statistics, which show a marked reduction in runway incursions from 2009 to 2010, with the six incursions last year down 50% on 2009. Given that 67 incursions took place in 2000, the long-term trends seem to be improving, too.
With the smart integration of physical technologies and IT-based communications systems, along with detailed and extensive staff training programmes, airports worldwide should be able to enjoy a future in which incidents on the runway become ever more rare.