Role of medical factors in 1000 fatal aviation accidents: case note studyBMJ 1997; 314 doi: https://doi.org/10.1136/bmj.314.7094.1592 (Published 31 May 1997) Cite this as: BMJ 1997;314:1592
- S A Cullen, consultant pathologista,
- H C Drysdale, consultant pathologista,
- R W Mayes, principal toxicologistb
- a RAF Department of Aviation Pathology, RAF Institute of Health and Medical Training, Halton, Buckinghamshire HP22 5PG
- b RAF Department of Aviation Toxicology, RAF Institute of Health and Medical Training
- Correspondence to: Dr Cullen
- Accepted 29 November 1996
Sudden illness in flight is said to cause 1.5% of fatal general aviation accidents.1 This study reviews the experience from the United Kingdom.
Methods and results
We reviewed the findings of 1000 consecutive accidents between 1956 and 1995 for which a consultant from our department either performed or attended the necropsies. Medical or toxicological factors caused or were a contributory cause in 47 accidents (table 1). Cardiac disease in the pilot was the most common factor. In one case the collapse of a front seat passenger in a light aircraft was thought to have distracted the pilot and caused the accident. The other medical causes in private pilots included nine cases of alcohol intoxication and three definite suicides. Central nervous system disorders contributed to seven accidents; three pilots were thought to have had epileptic fits, one had encephalitis, one a pituitary tumour, one haemorrhage from a cerebellar arteriovenous malformation, and one with a history of migraine radioed a report of visual disturbances and numbness before his crash.
Finding disease in the crew does not mean that it is the cause of the accident. Usually it is a coincidental finding. The main problems of interpretation are that the signs of trauma are superimposed on the disease process and that the victims often have such serious injuries that meaningful examination of their organs is impossible. For example, we know of a case where a young helicopter pilot collapsed on his way to his aircraft. He was admitted to hospital where he died of a haemorrhage into a cerebral metastasis from a minute testicular teratoma. Had he died while flying his brain would probably have been severely traumatised. Even if the tumour had been found it would have been difficult to determine if the haemorrhage caused the accident or was caused by it.
The history of the flight and accident is essential for accurate interpretation of pathological findings in aviation accidents. In this series most of the pilots had cardiac disease. Often there are no signs of acute changes and pathologists rely entirely on history. Haemorrhage into an atheromatous plaque has been seen occasionally, and in these cases staining for iron showed the presence of haemosiderin laden macrophages suggesting that there had been previous bleeds into the plaque. This contrasts with the bleeding caused by direct trauma to the heart which is adventitial rather than within the plaque and has no demonstrable haemosiderin.
The commonest cause of incapacitation in flights not resulting in accidents is neurological disorders.2 3 However, neurological disorders were under represented in our series, probably because of the difficulty in postmortem diagnosis and the severe cerebral damage that often occurs in aviation accidents.
The 2.4% rate of alcohol intoxication in private pilots is comparable with that reported elsewhere4 but is much less than the third of private pilots quoted in the British Medical Association booklet Alcohol and accidents.5 Interestingly, five pilots were clearly drinking while flying as the remains of spirit bottles were found in the wreckage. One of these cases may have been suicide and in three others in which the pilot was not intoxicated we are certain that the pilot took his own life.
We thank Professor J K Mason and Drs P J Stevens, A J C Balfour, and I R Hill for their meticulous case notes and accident analysis.
Conflict of interest: None.