In his recent article (''Sense of foreboding in the air as watchdog muzzled'', August 25, p11) John Woods asserted that the Civil Aviation Safety Authority should return to the good old days of ''product surveillance by qualified and current CASA pilots and engineers''.

It may have escaped his notice that air transport regulatory authorities all over the world have taken the same path as CASA, not because of pressures to reduce cost, but to improve safety.

The concept of a CASA auditor checking line operations was flawed for a number of reasons.

Firstly it is impossible to check everything done on line operations. Secondly studies have demonstrated that a ''quality auditor'' can actually reduce safety by leaving the burden of oversight to the regulator rather than ensuring that the flying organisation has in place a system of checks and balances a safety management system. An organisation's safety system will be far better than any that a regulator could provide.

One example demonstrates this. When CASA used to have its own pilots flying in cockpits with airline crews, in most cases the CASA pilot had far fewer hours, and far less experience than the crews supposedly being checked. They were not regarded highly by the airline crews and often were out of date with the latest techniques, aircraft and flying practices. They added little if any value to the ongoing safety improvement program. (However, these checks did provide wonderful ''jollies'' for the CASA pilots).

A properly constructed and executed safety management system is a far better method of ensuring airline safety, and has been pursued by authorities around the world, not just in aviation, but in other industries such as mining, oil and gas.

The regulator's role is to ensure that airlines have an effective system in place. The International Civil Aviation Organisation has mandated such systems for all member states, and it will become law in 2009.