THE National Transportation Safety Board (NTSB) probing the fatal February 23 Atlas Air Boeing 767-300 freighter crash near Houston are stumped over a sound on the voice recorder signifies the activation of the go-around switch immediately before the crash sequence.
NTSB investigators have released detailed information on the cockpit-voice and flight-data recordings, as well as a spectral analysis of certain sounds in the cockpit, reported London's Air Cargo News.
The aircraft, which was flying on behalf of Amazon Air, suddenly entered a steep dive into Trinity Bay from 6,000 feet while preparing for an approach to Houston.
Cockpit conversation indicates that the flight was progressing normally; with a call to start extending the flaps heard some 60 seconds before the impact.
But just under 30 seconds after this 'flaps 1' call, and shortly after the jet encountered moderate turbulence, the recorder picks up the sound of a click, the origin of which has stumped the inquiry.
The time alignment of the click, it says, matched flight-data recorder information showing activation of the go-around mode.
Spectral analysis has been conducted to try to establish the likely source of the sound. Although the recording quality was poor, investigators have used filtering and detailed comparison with the double-click of a 767 go-around button being pushed and released to try to identify the noise.
The inquiry says the mysterious click on the cockpit recorder 'shares a similar characteristic' to the go-around button activation, and that it 'could potentially be associated' with the release portion of the double-click.
'However, it cannot be conclusively determined if it is the same sound due to the degraded quality of the [recording] at the time of the sound detection,' it stated.
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NTSB investigators have released detailed information on the cockpit-voice and flight-data recordings, as well as a spectral analysis of certain sounds in the cockpit, reported London's Air Cargo News.
The aircraft, which was flying on behalf of Amazon Air, suddenly entered a steep dive into Trinity Bay from 6,000 feet while preparing for an approach to Houston.
Cockpit conversation indicates that the flight was progressing normally; with a call to start extending the flaps heard some 60 seconds before the impact.
But just under 30 seconds after this 'flaps 1' call, and shortly after the jet encountered moderate turbulence, the recorder picks up the sound of a click, the origin of which has stumped the inquiry.
The time alignment of the click, it says, matched flight-data recorder information showing activation of the go-around mode.
Spectral analysis has been conducted to try to establish the likely source of the sound. Although the recording quality was poor, investigators have used filtering and detailed comparison with the double-click of a 767 go-around button being pushed and released to try to identify the noise.
The inquiry says the mysterious click on the cockpit recorder 'shares a similar characteristic' to the go-around button activation, and that it 'could potentially be associated' with the release portion of the double-click.
'However, it cannot be conclusively determined if it is the same sound due to the degraded quality of the [recording] at the time of the sound detection,' it stated.
WORLD SHIPPING