An aviation expert says the mechanisms are in place to keep helicopter pilots safe - but the job will never be risk free.

Experienced pilot, Peter Robb, died while spraying farmland northwest of Wanganui yesterday morning.

An Airline Pilots' Association safety investigator, Gary Parata, says the industry's done things like reduce the number of hours pilots can fly in a day to increase safety.

"There's been a steady decline in the rate of accidents occurring to all agriculture and operations, and in particular helicopters, which is very pleasing to see.

"That doesn't prevent these accidents from happening."