Helicopter tour crashes in Hawai'i have dropped sharply since the Federal Aviation Administration tightened regulations on such tours in 1994, according to a report released today.

The study, done by researchers at the Johns Hopkins Bloomberg School of Public Health, compared crashes from 1995 to 2008 with those from 1981 to 1994. The study found that the crash rate for helicopter tours fell 47 percent after the stricter regulations went into effect.

"In summary, we found that after the 1994 rule, the estimated crash rate was reduced by almost half and fewer crashes and deaths have been associated with ocean ditching," researchers wrote.

The study was limited to helicopters, which comprised 80 percent of all sightseeing aircraft that crashed in Hawai'i from 1981 to 2008. Of the 59 total crashes during the period, the majority — 34 — were attributed to aircraft malfunctions, according to the study.

The FAA rule was put into place after an escalation of Hawaiian air tour crashes in 1994. That year, when approximately 97 helicopters were flying air tours, 10 of them — one-eleventh of the fleet — crashed, according to the study.

Among other things, the regulations placed a minimum flight altitude of 1,500 feet above terrain for helicopter tours. They also required improved safety procedures such as detailed passenger briefs, as well as a requirement for aircraft flotation equipment including life vests for all passengers on ocean-front flights.

However, the study also noted that the National Transportation Safety Board recommended in its annual report that more attention be paid toward maintenance, pilot training and restricting flights to operating areas and conditions that enable safe emergency landings.

Nationally, 2008 had the lowest amount of sightseeing crashes in the past 26 years for both fixed-wing aircraft and helicopters. The nation's air-tour industry experienced six aviation accidents last year, including two in Hawai'i, according to the FAA.

In Hawai'i, there was an average of 2.5 air fixed-wing and helicopter tour accidents annually over the past 10 years, down from 3.6 per year during the 1990s. On average, that's less than one fatal air tour crash per year for the past 20 years.