The usual method of countering bird strikes is for airport operators to implement ground-based detection and deterrent techniques and technologies - habitat management, radar detection of bird flocks, using dogs and birds of prey to scare the birds away, and so on - but there's now a growing trend for fitting automated bird-deterrent systems on board aircraft, which work in tandem with airport radar.
The technology currently falls into two broad camps - pulsed landing lights and ultrasound generators, the former being more established. The idea of course is that aircraft of any size (including helicopters) can carry this capability with them wherever they fly, but is only activated if necessary on take-off and landing, when the vast majority of bird strikes occur.
Ultrasound technology is still at an early stage, although the principle is simple - to project sound waves in front of the aircraft at frequencies beyond human hearing to scare birds away. The development of one such system was announced in October 2010 by Devonhill Technology Partners, but apart from that the technology still appears to be largely at the research stage.
Pulsed-lighting systems, however, are already in service with some airlines and other operators, and commercial prospects look healthy for both types of technology.
As Balaji Srimoolanathan, programme manager, aerospace and defence, at consultancy Frost & Sullivan, says, "While my feeling is that light-based deterrent systems would be more effective, since birds rely more on vision than sound, I can see there being a case for both types of technology on board, depending on the scenario.
"Whichever the technology though, it's extremely important to have them on board because different airports have different facilities and environments, and there are no global regulations in this respect so airlines have to mitigate the risks themselves. Potentially the market for these onboard technologies is a huge one," he says.
Onboard bird strike technology
Perhaps the best known onboard system at the moment is Pulselight, from US company Precise Flight, which has been adopted by more than a dozen carriers including Alaska Airlines and Qantas.
Essentially, Pulselight is a box of electronics that causes an aircraft's normally steady taxi or recognition lights to flash rapidly in various patterns, giving a better warning of the aircraft's approach and therefore more time for birds to bet out of the way. It integrates with traffic collision and avoidance systems, which can automatically activate it should they need to, and can be retrofitted.
In trials on Boeing 737s between 2005 and 2007, Qantas found the system achieved a reduction of up to 66% in bird-strike rates per 1,000 departures (day and night) compared with 737s without the system; the system has now been adopted on its domestic fleet. As a result of these trials, Alaska Airlines began fitting the system on its 737 fleet in 2010, and claims a return on its investment of two years.
Elsewhere in the US, the system is also now available as an option on most new business jets, has been adopted by the Houston and Los Angeles police departments and is mandated for aerial firefighting as well as for helicopter tour operators in heavily congested areas such as New York.
Despite this take-up though, opinion varies as to who should be fitting the technology - airlines or manufacturers. British Airways, for example, says it's down to the manufacturer. According to a spokesman, "There are technologies coming in but the route into it is via Boeing, Airbus and so on."
Yet Boeing, for example, says, "We work with industry on the issue. We continue to follow the development of technologies directed toward reducing bird strikes, to assess their maturity and overall benefits, but we have no plans at this time for incorporation."
Others remain tight-lipped. American Airlines and Airbus, for example, simply said they weren't able to comment.
This seems surprising, especially when you consider that bird strikes are estimated to cause damage worth $400m in the US alone and $1.2bn worldwide every year to commercial aircraft and that, according to Srimoolanathan, this technology would be most important for larger aircraft with wing-mounted engines - which includes the type of craft built by these manufacturers and operated by these airlines.
Boeing's point about maturity, however, might offer a clue here. Even for pulsed lighting, take-up so far has been confined mostly to national or domestic carriers and local operators, and the aviation industry is notoriously conservative, so any new technology usually takes years to come into service - in fact, by the time it does, it isn't "new" any more.
Only part of the solution
And as Srimoolanathan points out, this onboard technology is just one tool in the box. "It's only part of the solution," he says, "and it has to work hand in hand with perhaps more important preventative measures such as ground / habitat management within the airport area to reduce its attraction to birds in the first place, and even in neighbouring areas using measures such as clearing urban litter to remove potential food sources."
The thinking in some quarters, however, is that by shifting some of the responsibility for avoiding bird strikes to airlines and other users of airspace, fresh investment in ground infrastructure can be avoided. But that argument is a non-starter as far as Srimoolanathan is concerned: "Airports have technology in parallel with this, but investment can't come from just the airports or airlines, it has to be a joint approach."
Detection systems are a case in point. "The emphasis must remain on radar detection," he says, "and although it would be good to have that onboard the aircraft, its high cost makes it untenable for the foreseeable future at least."
Onboard systems are on their way though, so when you see an aircraft flashing its lights as it takes off or comes in to land, remember that they're just trying to fly that bit safer.