Aviation regulators have been urged by safety consultants to consider extra restrictions for trainee pilots making multiple attempts to pass flight tests.
The Aerosafe Risk Management consultancy's advice is in a review commissioned by the Civil Aviation Authority after 13 deaths in 135 flight training crashes in 11 years to 2010.
According to a separate survey of 470 commercial pilot trainees from six aviation schools, only 65% passed flight tests on their first try, and almost 10% required more than two attempts.
Aerosafe said although there were some restrictions on re-sitting flight tests, it was worth considering how appropriate it was to issue professional licences entitling such pilots to carry fare-paying passengers.
The CAA says it is taking steps to obtain better statistical reports on examination and flight test performance to assess what types of intervention may be needed.
The Transport Accident Investigation Commission, also cited in the review, said training aircraft accounted for almost 60 out of 131 near collisions reported in the past 11 years.
That compared with just three training aircraft involved in close calls between 1990 and 1999, out of 17 such incidents reported in total.
Aerosafe said having more "near misses" reported reflected a more open safety culture so was very positive.
But the consultants made several recommendations aimed at reducing the risk of training crashes, including to review and simplify aerodrome procedures and "airspace design" to ensure trainee pilots are not distracted from looking out for other aircraft and hazards.
After two student pilots were killed in a midair collision over the Manawatu in 2006, there were found to be no procedures governing the maximum number of aircraft which could operate in the area.
Neither was there any formal briefing between instructors on the training area being used, even though both aircraft were from the same aviation school, at Massey University.
The consultants said aviation training was of significant economic importance, having doubled from 98,000 training hours in 2000 to more than 198,000 in 2009, generating $53 million in annual income.
Although New Zealand was still seen as having a good safety record, incidents and accidents jumped from 81 for every 100,000 flying hours in 2000 to 202 reported last year.
Four people were killed in two training crashes last year, compared with two deaths in 2009, three in 2003, and none in five of the 11 years.
Although the increase could not be conclusively attributed to any change in the industry, the consultants pointed to an analysis by the aviation authority which noted a 200% increase in commercial licences issued to foreign nationals from 2006 to 2010.
An economic analysis last year estimated aviation training generated $15 million in "export" revenue annually from non-New Zealanders, and forecast that to rise to between $24 million and $56 million by 2015.
