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North American culture seems to embody some rather odd
attitudes to safety of different modes of transportation.
Perceptions of danger and assignment of responsibility differ
among modes.
Aircraft
I think it is safe to say that flying involves putting oneself
in quite an untenable situation, compared to ground based modes.
One cannot just stop and step out. Control failure, engine
failure on takeoff (often caused by striking a bird), excessive
icing and encounters with thunderstorms can be immediately fatal.
Engine failures can result in a glide (by autorotation, in the
case of helicopters) to earth and a forced landing at a
potentially hostile location. Flying at high altitudes involves
the risk of sudden loss of pressurisation requiring an immediate
emergency descent. Flying in cloud requires the use of ground
based air traffic control to avoid collisions. Instrument
approaches require vigilant crews and reliable avionics - yet
people still fly into the ground by descending below legal
minimums or by omitting to properly set the altimeter.
Despite the hostile environment and multitude of possible
"gotchas", travel by aircraft is indeed relatively
safe. It is a tribute to the professionals (designers, builders,
inspectors, pilots, controllers) in the industry that the safety
record is as good as it is. This safety comes at a huge economic
cost, however - new aircraft designs and modifications to
existing designs must be extensively tested, a large amount of
preventive maintenance must be done, hugely expensive avionics
are required (possibly including an inertial reference system, a
ground proximity warning system, cockpit voice and data
recorders) and a huge bureaucracy exists to implement and enforce
safety regulations.
Pilots are immersed in a safety culture - they learn all the
risks of flying, how to assess them, and hopefully some decision
making skills that will help them make good decisions. One
decision that is sometimes made and must be considered is simply
to not go, or to return once airborne. The pilot in command of a
flight is legally responsible for just about anything that can go
wrong. She or he is responsible for the airworthiness of the
aircraft, even though certain things cannot be checked in the
walkaround of a large aircraft. Airline transport pilots must
pass an extensive medical exam every 6 months, and must
continually undergo recurrent training.
Despite all these measures, however, the safety record is not
improving. It appears that we have reached the limit of what can
reasonably be done, and that "human error" (caused by
loss of situational awareness, fatigue, ..) and just plain bad
luck will continue to cause accidents.
Rail
Modern rail travel is incredibly safe. For example, there has
never been a fatal accident involving a TGV (train à grand
vitesse - high speed train) in more than 14 years of service, at
regular speeds of 300 km/h (originally 270 km/h) and headways
(time between trains) as low as 4 minutes.
The major dangers in rail travel are derailment and collision.
Derailments are quite uncommon if regular maintenance of track
and switches and rolling stock is performed. Collisions are
uncommon because of highly reliable, automatic, fail-safe
signalling systems. Railway signalling is too large a subject to
get into in detail here, but basically the concepts are:
- trains are automatically detected due to their axles
shorting out the two rails
- any failure in the signalling system results in a
"red light" (fail safe)
- signalling systems are designed so that a train always
has enough time to come to a complete stop if the train
ahead were to stop instantaneously (the "brick
wall" assumption) and the train behind has a partial
brake failure
- some signalling systems (metro/subway lines especially)
have mechanical devices which activate the brakes of a
train which is (incorrectly) passing a red signal
Note that Murphy can strike here as well, as is evidenced by
the recent Toronto Transit Commission subway crash. That crash
involved both driver error and mechanical failure of the system
designed to activate the brakes in the event of driver error. No
system is ever 100% fail-safe.
Road vehicles
A huge number of people are killed or injured in cars every
year. Driving itself should not be tremendously dangerous,
although it does involve risks that flying does not. For example,
passing within metres of opposite direction traffic at high speed
involves the risk that the other driver may not be competent or
may be impaired, the other vehicle could have a mechanical
failure (e.g. steering) or could lack traction resulting in a
loss of control.
A driver's licence is required to operate a vehicle on public
roads, but in many jurisdictions the test required to obtain a
licence is ridiculously easy. In most cases the licence is valid
for life, with no retest ever required. In British Columbia this
is even true of truck and bus driving licences, although a retest
may be requested by the ministry at any point.
Safety standards for cars apply only to their initial
manufacture. Add-ons and modifications do not need to meet any
safety standards, or at least none that are enforced. No
requirement exists for regular inspection of cars. Trucks and
buses, on the other hand, require safety inspections at regular
intervals and are subject to inspection at many roadside
inspection (weigh) stations.
The most bizarre thing about cars, however, is that
responsibility for accidents involving adverse weather conditions
is very rarely attributed to the driver. I will wager that in any
one week you will be able to find in your local paper a report
about a "traffic accident" which was caused
by weather conditions. For example, a recent Canadian Press
report was headlined "Fog blamed in vehicles' pile-up"
and contained the following first paragraph:
Thick fog and slippery roads caused a traffic tangle
Thursday in which seven tractor-trailer units, a school bus
and several vehicles collided on a southern Alberta highway.
The report makes it sound as if the accident were "an act
of God". What about the responsibility for safe operation of
the vehicles? Is that not the drivers' job? If weather conditions
deteriorate, one must drive more slowly and carefully, or
perhaps even stop or decide not to make the trip in the first
place. This is not commonly done, I believe, because
- a lot of areas are built so as to require travel by car
- driver training does not emphasise the "think about
the trip before you go" checklist type of thinking
emphasised in flying
- a person who decides to not go due to weather is often
looked at as being overly cautious or "chicken"
I can just imagine the reaction if an inquiry into an aircraft
crash stated that the crash was caused by fog, and not that the
crash was caused by the pilot's failure to conduct a missed
approach and divert to an alternate airport.
James Strickland
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