He was part of a Westpac helicopter crew on a mission near Newcastle to find Folkard's attacker, suspected to be a bull shark. From the air, his colleague spotted a figure against the sand, possibly a great white, gliding towards an unsuspecting surfer.

''My heart sank. We thought we were going to witness something really bad,'' Nickisson said later. ''We really feared for this bloke's safety - it was dire.''

The helicopter hovered to warn the surfer, who caught a wave to shore, but it was not the only shark the crew would spot that afternoon.

The water was teeming with the predators, lured in by thousands of bait fish, prompting authorities to close beaches along the coast.

Nickisson and his colleagues conduct shark patrols only occasionally but he describes them as ''very effective'', adding ''you can see a lot more from the air than you can from the ground''.

A damning government report on aerial shark sighting tells a different story, however, fuelling questions over whether the measure protects swimmers from attack, or simply deludes them into feeling safe.

''The chances of seeing a shark [from the air] are extremely slim,'' says Vic Peddemors, a shark biologist and one of the state's foremost shark experts. ''Shark attacks are such a rare event, is aerial patrolling really the best way to spend public money?''

The report by the Department of Primary Industries, co-written by Peddemors, found that despite strong public support, aerial patrols were ''extremely limited'' in their ability to detect sharks, ''giving the public an inflated sense of protection against shark attack''.

The findings, released last year, were based on a trial at Jervis Bay using artificial sharks, placed at various depths.

It found fixed-wing aircraft crews spotted just 12.5 per cent of the dummies, while helicopters - the main form of government-funded patrols in NSW - detected 17 per cent.

A spate of shark encounters in NSW has reignited debate over the best way to protect beaches.

Last month, a surfer lost a finger and suffered serious thigh wounds after being attacked by a shark on the mid north coast.

On Sunday, a 2.5-metre great white attacked an off-duty lifeguard near Dee Why, taking a large chunk from the 23-year-old's surfboard.

And at Bondi on Tuesday, a shark sighting prompted thousands of bathers to scurry ashore.

Despite a spike in shark encounters each summer, Peddemors says the rate of attacks in NSW has remained stable over the past 20 years, even though the population and recreational ocean use has increased.

Figures from the Australian Shark Attack File, maintained by Taronga Zoo, show there is one unprovoked shark fatality each year in Australia, on average, from an estimated 100 million annual beach visits. By comparison, an average of 121 people drown at the beach annually.

Christopher Neff is a PhD candidate at the University of Sydney, who is conducting the first doctoral study of policy responses to shark attacks.

He says media reports of shark sightings focus on threatening sharks seen ''lurking near bathers'' rather than those that swam peacefully away, which drives unrealistic public fears of attack.

In response, Neff says, the government enacts measures such as aerial patrols, which he describes as nothing more than a ''confidence building exercise''.

''I think it's important to build public confidence, so long as you are telling the public the whole story and you don't lull them into a false sense of security,'' he says, calling for beach signs that advise swimmers of shark dangers. ''You've got to be honest that there is no such thing as zero risk.''

Under a state government contract, Newcastle Helicopters is conducting aerial beach patrols in NSW this summer from Seal Rocks, on the north coast, to south Wollongong.

The Minister for Primary Industries, Katrina Hodgkinson, would not say whether the patrols would be funded next summer, referring questions to the department.

A departmental spokesman would not disclose how much the government pays for aerial patrols each year, saying the figure was ''commercial-in-confidence''. But the Coalition committed $200,000 a year to aerial shark surveillance and shark safety research before the last election, he said.

Other aerial patrols rely on public and corporate donations.

''There are no 100 per cent guarantees when entering the ocean but the government is willing to do all it can [to] reduce the risk to the people of NSW and ensure they have an enjoyable summer,'' the spokesman said.

The previous Labor government withdrew its support for aerial shark patrols in 2007 after a NSW shark protection summit questioned their value. They were reinstated in 2009 and they have been conducted each summer since as the government assesses their usefulness.

The spokesman said aerial shark patrols continued ''to provide a full scientific evaluation of aerial surveillance as a bather protection measure'', adding that alternative methods were being investigated, such as unmanned surveillance vehicles.

A spokesperson for Newcastle Helicopters declined to comment.

However Barry Sandry, a pilot at the Australian Aerial Patrol in the Illawarra, insisted aerial shark patrols were a valuable early warning system. The organisation took part in the shark sighting study in the summer of 2010-11.

Sandry says about 12 sharks are spotted on a typical patrol. Those at a safe distance from swimmers prompt a radio alert to lifeguards but ''if someone is in danger, we fly at a very low level, we have sirens on board and a PA system so we can move people out of the water as quick as we can'', he says.

The service, which receives little government funding, costs about $800,000 a year to run - bankrolled by its major sponsor, Bendigo Bank, other community contributions and revenue from the organisation's commercial arm.

Sandry insists that it is money well spent.

''It is going to make people feel safer, knowing that the patrol is going over the top [of the beach] and they are swimming in an area considered safe,'' he says.

''You get comments from people - they say things like 'it's good to know you guys are there'.''

Allaying fears is part of the job but the benefits are real, Sandry says.

''We've been operating for 57 years … we know the [shark] activity that is out there on a daily basis. If the service wasn't effective, we wouldn't continue to do it,'' he says.

The report argued the best alternative to aerial shark patrols was bolstering funding for lifeguard-run beach surveillance programs and expanding the government's shark awareness program, Shark Smart.

Peddemors hopes that by drumming home the shark safety message, knowledge of the risks will become ''second nature'' to beach users. But he conceded that primal fears were hard to shift.

''It doesn't matter whether you live here or in America or South Africa or India, I think it's an inbred fear of being eaten by another animal,'' he says.