Readers will be aware of the "Sticky" on the availability of the complete series of the former Aviation Safety Digest in digital form on the CASA website.
In August 1965, a Viscount 832 was en-route from Canberra to Melbourne when No.1 engine propeller autofeathered followed shortly afterwards by an uncontrollable fire in the nacelle. The captain diverted to Mangalore, Victoria, where an emergency landing was made in the dark with all emergency services standing by. Thanks to the actions of the flight crew and the efficiency of the fire crew, the intense fire was confined to the engine nacelle and all occupants were able to evacuate the aircraft safely.
An excellent four page summary of that incident was published in Issue No. 45 of Aviation Safety Digest, March 1966. See:
https://www.atsb.gov.au/media/5774742/asd_45_mar_66.pdf
The editorial comment included in the article, quoted an RAAF source which applies today just as much as 55 years ago.
It said "Nothing in this life is infallible, and yet, to be effective, a fire warning system must be as close to it as possible. if it is to fail, it should fail safe. Of the two failures possible, it is preferable to have a warning where no fire exists on occasions, than to have a fire where no warning is given. To ensure the highest possible reliabilityin detecting a fire, the system must be sensitive to as many manifestations of fire as possible. This makes the problem of discrimination most difficult. Technical effort and research is constantly striving to eliminate the false warning but it will never be entirely successful.
"False fire warnings amount to a 'fail-safe' protection only so long as the aircraft captain treats every warning as a real one. If he is prepared to wait for a more spectacular evidence of fire before taking postive action, a fire warning system is useless."
And, we could add, his first "real" warning is likely to be his last!
The above opinion ruefully reminded me of when I first flew as a 21 year old co-pilot on Lincoln bombers. . I was told that false engine fire warnings were common in the Rolls Royce Merlin engines of the Lincoln. The technique commonly used to confirm if there was a real fire following a fire warning, was to turn the aircraft as quickly as possible to see if there was a smoke trail. if there was, then operate the engine fire extinguisher system. Try that when flying in cloud..
I next struck a similar "she'll be right Mate" attitude when one day flying as co-pilot to the Commanding Officer of the RAAF VIP squadron at Canberra. It was a positioning flight in a Convair 440 Metropolitan from Canberra to Sydney to pick up the then Prime Minister Sir Robert Menzies from Sydney.
30 miles from Sydney a fire warning sounded for No 2 engine. The CO was quite calm and treated the fire warning as false as he did not want to risk disrupting the PM's schedule. I could see him mulling over possible solutions to the dilemma.
He called Sydney ATC and told them he was returning to Canberra where he had quickly arranged for another Convair to be on standby so he could fly it to Sydney just in time to be on schedule to pick up the PM. All the time the fire warning engine was still running normally apart from its fire warning light glowing red. Eventually, after ten minutes into the return to Canberra he feathered the propeller. I don't recall if the warning light went out or not. He gave me the feathered landing for practice.
The point of all this was that things were different in those days. But it was all to easy to rationalise and think if there is no smoke then there is no fire
Nowadays ATSB reports appear more bland than in the old days of Aviation Safety Digest where the editor could be blunt in his comments and the reader could agree or disagree. The causes of aircraft accidents have changed little since the old days but the reporting is more cautious, more politically correct and scanned closely by the legal fraternity before publication.
The Viscount in-flight engine fire as written up in ASD No. 45 of March 1966 is a good example why todays pilots should not ignore the circumstances surrounding incidents and accidents of the past. For those interested, it's all there in those golden ASD gems available at no cost on the CASA website.