The price of domestic flights on small planes may increase $5 a passenger if the Government adopts new security screening measures.

An alleged hijacking last year prompted a review of aviation security which found some domestic flights to be at high-risk.

Asha Ali Abdille, a 34-year-old Blenheim vineyard worker, was accused of hijacking a passenger flight from Blenheim to Christchurch on February 8, 2008.

A summary of the report, released today, said domestic flights of fewer than 90 seats with unscreened passengers and carry-on baggage were a high-risk area.

Drunks, people with a metal illness and those holding an excessive grudge posed the biggest threat on domestic flights.

The threat of terrorism was found to be "very low".

The summary said greater screening of crew and carry-on baggage would be the best way to increase security.

In New Zealand 57 per cent of passengers on domestic flights are screened, including all passengers on the jets which have over 90 seats, compared to 96 per cent in Australia and 99 per cent in Canada.

The cost of such screening was likely to be about $5 per passenger on each additional screened flight - a total of between $121 million and $161m over 10 years depending on the type and volume of screening conducted.

The summary said airlines were likely to pass on the additional cost on to passengers.

"Airports and airlines do not consider that the risks faced by the domestic aviation system warrant additional screening."

Screening at smaller airports would be "prohibitively expensive" and it was suggested it be introduced at the country's 10 busiest airports (resulting in 92 per cent of passengers screened) or 14 busiest airports (97 per cent).

Screening is expensive and creates costs for airports, airlines and passengers, the summary said.

"Non screening measures do not mitigate the areas of high risk although they are much lower in cost."

Other options offered by the report included strengthening cockpit doors, security committees at airports and enhanced training and education for airport workers.

The Government would make a decision on security measures next month, Transport Minister Steven Joyce said.

"These are challenging and important decisions."

Abdille was also charged with taking an offensive weapon onto an aircraft and four charges, two of which relate to attacks on the pilots, of wounding with reckless disregard for safety.

The trial has been set down for two weeks in September with two days of pre-trial arguments from June 15.

The two Air New Zealand pilots who stopped the alleged attempted hijack, Ross Haverfield and Dion McMillan, were honoured with the International Airline Pilots' Association Polaris Award for heroism last month.