Gremline Flight Safety Report: Qualified And Authorised? / Acceptable Risk and MAO

the online flight safety digest

Text Box: qualified and authorised? / acceptable risk

the gremline digest — qualified and authorised? / acceptable risk

Qualified And Authorised?

 I once read an annual report on a junior officer that said, ‘His enthusiasm often outstrips his ability.’ I’m still not certain whether that was a good report or a bad one! However, working on an aircraft or any of its associated systems is no place to let one’s enthusiasm to get something fixed go beyond your level of qualification and authorisation.

We have probably all witnessed a helpful bystander offer to get his car to jump-start an aircraft with a flat battery. Not wise. Better to have a qualified engineer investigate why the battery is flat, rectify any fault and then fit a fully charged battery before the next flight. How many missing fasteners on your engine cowling are acceptable? Are you sure you have the correct type of fastener to replace those missing? Why are the fasteners missing?
‘Modifying’ a component on an aircraft is just another word for botching the job, unless you are qualified and authorised to incorporate an authorised modification. Let’s look at an accident that shows how serious the after-effects of a botched job on a piece of aircraft equipment can be.


A young and experienced glider pilot suffered serious injuries when he crashed into trees close to his intended landing point at an airfield. The glider was destroyed on impact. The left shoulder and lap straps of the pilot’s harness were found to have disconnected from the quick release fastener (QRF) during the impact, probably increasing the severity of the pilot’s injuries. There was no evidence of damage to the strap fasteners.

      The reasons for the crash were identified by the British Gliding Association (BGA) and are irrelevant to this discussion, which will concentrate on the reason for the failure of the pilot’s safety harness.
      The UK Air Accidents Investigation Branch (AAIB) conducted an examination of the QRF rotary buckle and the rest of the harness in collaboration with the QRF manufacturer’s representative in the UK, an expert metallurgist and, subsequently, by returning the buckle to its manufacturer in the USA.
      The rotary buckle is a metal housing with five slots to take the metal end fittings for two shoulder straps, two lap straps and one crotch strap. These end fittings may be released by rotating a four-vaned handle on the centre of the QRF clockwise or counter-clockwise, thus unlocking the harness. The release mechanism for the crotch strap or either of the lap straps may be deactivated so that the buckle remains attached to one piece of harness when the QRF is unlocked. The shoulder straps can be released separately by pushing forward on the tab located between the shoulder strap end fittings. The QRF buckle is a sealed construction and does not require internal checks or maintenance.
      Each strap end fitting is retained in the locked buckle by a restraining dog and a combination of ‘mushroom’ pins. Unlocking the buckle by rotating the four-vaned handle retracts each restraining dog inside the QRF. The buckle failed by the left-hand lap fitting pulling out of the buckle. For this to happen the detached mushroom pin found inside the QRF could not have been in place at the time of impact and physical evidence showed that it had been loose for some time. The way in which the mushroom pins in the failed QRF were riveted was compared to an example buckle from the same manufacturer. The method of riveting on the example buckle was stronger and offered greater resistance to pull-out.


The rotary buckle manufacturer found that the buckle, manufactured more than 20 years before the accident, did not match the rest of the harness. They made negative comments on the apparent lack of servicing of the buckle, which had become worn beyond the limits specified in the Component Maintenance Manual. They also criticised the method used to attach the harness to the glider fuselage structure. The webbing, the lap belt plug-in fittings and the webbing adjusters were from at least one other manufacturer. The Gliding Club stated that the harness had not been changed or modified since they acquired the glider, complete with the harness, 5 years prior to the accident.
     It does not seem unreasonable to assume that the QRF buckle had been subject to an unauthorised repair some time in the past 20 years. It also seems that someone somewhere put together a seat harness from bits and pieces of other harnesses. Finally it seems that the harness was neither inspected nor serviced on a regular basis.
      The failure of this harness highlights the need to ensure compatibility between all the components of a harness and to ensure regular periodic inspection and servicing.

The facts in this article are based closely on UK Air Accidents Investigation Branch (AAIB) Investigation Reference EW/C2002/06/05 which source is gratefully acknowledged. The full report may be seen by entering the above reference at   Any opinions expressed are those of the author and are not intended to represent the views of AAIB.



Acceptable Risk & MAO

 Risk taking is an essential part of human life. There cannot be life without risk. Western society seems intent on removing all aspects of risk from our daily lives. The ‘no win – no fee’ litigious culture seems to encourage us to blame anyone but ourselves for any mishap we suffer as we blunder our way through life. Trip over an uneven pavement and sue the local council instead of learning to look where you are putting your feet. Stumble against a wall and sue the owner for having built the wall in the ‘wrong place.’ I believe this culture is weakening all of us and is aiming at the unattainable goal of totally removing risk from everyday life. These thoughts led me to the idea that zero risk is only available to those who are already dead, so what level of risk is acceptable to those of us who are willing to recognise and accept some responsibility for our own actions?

Recent research confirms that each of us has a slightly different perception of what is ‘acceptable risk.’ It has been discovered that this variation in perception is at least partly determined by the levels in our brain of a particular protein called monoamineoxidase (MAO). This discovery may help to provide one answer to some of the puzzling aspects of safety promotion and accident prevention.
      Research shows that the lower an individual’s MAO level the greater is the level of risk deemed as ‘acceptable’ by that individual, and the higher the level of MAO the less likely is an individual to take risks. It is hardly surprising to learn that, in general, males have lower levels of this protein in their brains than females. Also that our levels of MAO tend to increase as we grow older. The observation that old women are generally more cautious than young men is worthy of the findings of a research programme at ‘The University of the Blindingly Obvious’, but the relationship to MAO levels is of interest.


It has been found that psychopathic criminals have particularly low levels of MAO so are apparently willing to take much greater risks in society than ‘normal’ people. Bullfighters as a group were also found to have low MAO levels – but there are some female matadors. It seems that if we are born with low levels of MAO then we will be high risk-takers for the rest of our lives, despite some moderation in older age. Perhaps, up to a certain level, high risk-takers are also high achievers? Can one achieve anything without some level of risk?
      Would it assist the selectors of fighter pilot trainees and future astronauts to measure MAO levels and reject those with levels higher than some pre-determined datum? The possibilities could expand to reject anyone applying for a job as a ‘Lollipop Lady’ at a school crossing unless she was over 65 and had an astronomical MAO level – but then she would probably not allow any children to ever cross the road just in case an unseen vehicle was lurking somewhere below the distant horizon.
      More seriously, it may be possible to discover an effective way in which to permanently adjust the level of this protein in mentally ill patients to return their MAO to ‘normal’ and so cure one aspect of their illness. It seems that currently available MAO-inhibiting drugs are going out of fashion as anti-depressants. Perhaps
boosting MAO levels would be more effective?
      It seems apparent that we cannot produce a zero-risk environment for human habitation. Even if we did, we couldn’t exist there. It is also apparent that we, as individuals, cannot agree as to what level of risk is ‘acceptable’ because what is acceptable to me may seem nannyish to a younger man and, at the same time, foolhardy to an old lady.


What has this got to do with Flight Safety? I think it may go some way towards explaining why some young macho male pilots are convinced that the REGULATORS in CAA/FAA, (or wherever the local rule makers sit), are a lot of old women who have forgotten all about real aviation while some of us older people working in Flight Safety are equally convinced that many young pilots are totally irresponsible and should be locked into the hangar with their aircraft.
      Both of these perceptions are (probably!) wrong. It seems that they are at least partially chemically determined in our brains and not much can be done to dramatically alter them at present. ‘Education’ and ‘persuasion’ can modify our perceptions and understanding, but there will always be a gap in individual definitions of ‘acceptable risk.’
      If we can recognise and accept this gap in perception then perhaps we can all concentrate on trying to keep flying reasonably safe without aiming at an impossible target and one that may even be undesirable.
      I have no idea what my own MAO level is, and have no desire to know. Despite being ancient, I still believe that a world totally devoid of risk would be a totally boring place to inhabit.



Search Now:
Amazon Logo



Text and Photographs 2008 Gremline & Hill House Publications, unless otherwise stated.


landing page about gremline copyright/conditions/contact information exchange glossary

uk emergency diversions uk links, chirp & gasco global & misc links forum

the gremline cockpit — index of articles the gremline bookshop top of page