Beech 1900 regional-aircraft operators should be required to inspect and repair deficient cockpit-voice recorders, the US National Transportation Safety Board (NTSB) has recommended.

Safety Board investigators say that they had trouble understanding crucial radio transmissions from the United Express Beech 1900 which collided with a Beech King Air A90 at the uncontrolled Quincy (Illinois) Airport on 19 November,1996, killing 14 people.

The NTSB says that similar deficiencies have been noted in five Beech 1900 accidents and incidents over the past two years, attributing the problem to the aircraft's isolation amplifiers.

"Beech Aircraft has been aware of this problem for more than a year, and informed the Safety Board that it had modified the audio amplifier to correct the problem on late-model aeroplanes," says the Safety Board.

Source: Flight International