2017 was the safest year in aviation history with zero
deaths from commercial passenger jets, and just 44 onboard fatalities attributed to the
aviation industry as a whole when military and cargo flights are factored in.
Despite ever increasing demand for flights and the number of passengers flying soaring
to 4 billion in 2017, the number of crashes has declined dramatically over the decades.
Figuring out why crashes have reduced so dramatically, we first have to ask ourselves, why do crashes
happen in the first place.
Although the number of crashes have continually fallen, the statistical cause of crashes has
remained fairly stable.
With pilot error, mechanical failure, severe weather, and sabotage being the consistent
highest cause of fatalities.
Let’s dive deeper into the history of aviation to see how the airline industry has adapted
to become safer over the past century.
Going right back to the early decades of the aviation industry, an era dominated by the
mailplanes and barnstormers, flying was a hugely risky endeavor.
Planes were cheap and operators valued timely delivery, over pilot safety.
Not that the competitive daredevil pilots needed much pushing.
Plane technology was in its infancy and crashes were frequent.
An airmail pilot during this period had a one in four chance in meeting their end at
the controls of their aircraft.
[1]
These cowboy days of flight were short-lived, with the arrival of increasingly expensive
planes, a burgeoning commercial passenger industry, and with the formation of the first
pilots union in 1931, operators were forced to think about reliability not only for the
safety of their passengers and pilots, but to protect their financial interests.
Profit was threatened even further after a landmark case in 1936 when the widow of the
fallen pilot, Joe Livermore, successfully sued Northwest Airlines for pressuring her
husband into flying in dangerous conditions, but overzealous employers could not be blamed
for all crashes, even in the case of Joe Livermore.
Livermore was an older pilot, which in these days meant you were in your 30s, familiar
with the navigation method of contact flying, using visual references on the ground to navigate,
which required flying below the clouds, where turbulence and terrain posed a much higher
risk.[2] Livermores Lockheed 10 was equipped with instruments that allowed him to navigate
above the clouds using electronic airways. and he was expected to use it.
The system used radio beacons that guided the pilots between stations along the intended
route.
Each beacon would transmit morse code in alternating 90 degree quadrants.
So, if you were flying in quadrant “A”, you would only be able to hear the morse code
for that quadrant “dit-dah”.
In the next quadrant, the “N” quadrant, you would hear the mirror image code “dah
dit”, and when flying between the two, the signals joined to form a steady tone.
This designated the airway, thus each beacon was capable of producing 4 airways.
This system relied completely on the pilots ability to decipher the signal and static
could interfere with the reception.
Not only this, but pilots had no way of knowing if they were heading toward a station, or
away from it.
Getting lost with a plane that has limited fuel is obviously not ideal, and passing through
cloud cover without certainty of the terrain below was a harrowing experience.
It wasn’t unheard of for phantom radio signals from distant stations skipping through the
atmosphere luring pilots to their deaths either.
While this method of flying is vastly safer than flying in the lower atmosphere, to avoid
pilot error, pilots needed reliable fool-proof equipment that will not lead them astray.
Radio navigation is still in use today, but has improved dramatically.
Computers now interpret the radio signal and provide a read out on instrumentation such
as the automatic direction finder, the oldest radio navigation instrument still in use,
which points the pilot in the direction of the tuned station, and autopilot systems are
capable of tracking a selected route using this method.
Yet even with dramatic improvements, catastrophic incidents were still possible due to pilot
error.
Take Korean Airlines Flight 007, where the pilots incorrectly programmed the autopilot
system, causing the plane to track a straight bearing over Russian airspace, where is was
shot down.
This event led to further improvements to autopilot interfaces to reduce the chances
of pilot error, and was the primary driver for the Ronald Reagan administration opening
Global Positioning Satellite access to the world.
Providing even more redundancy to the tools pilots rely upon to safely complete their
job.
The importance of reliable instrumentation cannot be overstated.
Navigation errors are now a thing of the past, but they are not the only instrumentation
that a pilot relies upon.
Faulty sensors, like pitot tubes, which are these tubes that you can see on the outside
of the plane that measure airspeed, can be attributed to several crashes over the past
decade.
Flying a plane without reliable speed data, is incredibly difficult, if not near impossible.
The 2009 crash of Air France Flight 447, which killed 228 people, is a perfect example of
this.
Pitot tubes work simply by measuring the pressure caused by force of moving air attempting to
enter the tube.
The faster the plane travels, the higher the pressure, allowing the pitot tube to measure
air speed very accurately.
The pitot tubes of flight 447 failed as it was flying through the inter-tropical convergence
zone, an area prone to thunderstorms.
Here the pitot tube began to fill with ice, blocked the passage of air to the sensor and
thus dropping the air pressure.
The aircraft registered a malfunction and turned off the autopilot, giving manual control
over to a panicked crew who have no visual horizon in the pitch black of a storm and
proceeded to enter the plane into a stall resulting in the deadly crash into the Atlantic
ocean.
It took 2 years to find the black box and discover the exact cause of the crash.
Pitot tubes are equipped with drainage holes and heating elements to prevent this kind
of problem [4], but this particular model became overwhelmed with ice before it could
be cleared.
After this crash Airbus replaced these flawed pitot tubes, and pilots were warned of the
problem, which brings us to our next life saving measure.
The humble checklist.
Just 3 years after this fatal crash, a very similar problem struck to a Ryanair flight
on approach to Riga airport through moderate snowfall, when the pitot tube heater failed.
When speed measurements became erratic and the autopilot switched itself off, the pilots
were quick to level off flight at 4000 feet and began to work their checklist.
Checking each pitot tube output and comparing it with measurements from alternative sensors
like the inertial reference system to figure out which sensor was faulty, allowing them
to find a reliable read out on the captains sensors and safely land the plane.
[5]
The history of aircraft safety is defined by trial and error learning Accidents by their
very nature are caused by unpredicted circumstances, and even our understanding of weather has
improved through our obsession with flight, take the discovery of the Microburst weather
phenomenon, that mysteriously downed multiple planes like Delta Flight 191.
Microbursts are characterised by a column of rapidly descending air that spreads out
horizontally as it strikes the ground.
Microburst are perhaps the most dangerous of all weather phenomenon that threaten planes,
with strong erratic winds.
Imagine a plane flying into a microburst.
At first it will experience strong turbulence and a perceived increase in airspeed as the
plane encounters a strong headwind, tempting the pilot to reduce power.
Next the plane encounters the incredibly strong downburst of air, which could be enough to
down the plane alone, and as it passes through the downward draft the air direction flips
suddenly to a tailwind, resulting in a sudden loss of lift which would be made even worse
if the pilot had indeed reduced power when the headwind was encountered.
These effects combined resulted in Flight 191 hitting the ground a mile short of the
runway.
Killing 134 of the 163 on board and one person on the ground when the downed plane collided
with a car.
This crash, along with several similar prior crashes, resulted in a 7 year investigation
by NASA and the FAA, resulting in the discovery of the microburst phenomenon, and the introduction
of on-board wind shear radar to detect them.
There has only been one crash attributed to microbursts since.
This improvement may never have been possible without the black box, which gave researchers
vital data on the airspeeds flight 191 encountered, helping them to piece together an incredibly
difficult puzzle.
The black box was introduced in 1953 after a string of crashes of the De Havilland Comet,
which fell foul of unforeseen stress concentration in the corners of it’s square windows and
fatigue stress from repeated pressurisation cycles, leading to the introduction of round
windows and better consideration of fatigue stress, but also inspired Australian inventor
David Warren to provide a tool to help air crash investigators solve their mysteries.
It’s a simple concept.
A heavily protected box that can survive fire, water and impact.
It is perhaps the most valuable tool at our disposal in our quest to minimise the likelihood
of future crashes.
Yet, even now, this technology is not perfect.
Crashes like Malaysian Airlines MH370 remains a mystery as the blackbox was never found,
and it’s likely policies will be changed to have flight data continually streamed in
real time to ground stations to eliminate the need to locate the flight recorder after
a crash.
[6]
We could be here all day detailing these learning experiences, but that’s the core of why
flying has become radically safer.
We are continually learning and preventing repeated mistakes.
Systems have continually improved to drastically reduce the chances of human error, the largest
contributor to crashes.
Systems like fly-by-wire have been developed that prevent pilots from pushing the plane
beyond it’s capabilities, instruments at the pilots and air traffic controls disposal
have improved and been computerised, engines and flight structures have become vastly more
reliable, and our ability to predict and avoid adverse weather has improved and navigation
is now pinpoint accurate thanks to GPS.
But these improvements don’t explain the radical difference in safety between airlines
and countries operating in the same year.
The odds of you dying on the top 39 safest airlines is about 1 in 20 million, reverse
that and take the bottom 39 airlines and your chance is 1 in 2 million [3], ten times the
likelihood.
It’s not hard to differentiate between the top airlines and bottom airlines, the key
difference being an airlines ability to maintain older aircraft or buy new ones.
Iran exemplifies this problem with 94 airliner accidents in the past decade, resulting in
741 deaths.
Much of this can be blamed on the sanctions placed on Iran forcing them to rely on older
unreliable aircraft, which have not benefited from lessons of the past.
The problem is further compounded with a severe lack of replacement parts, preventing vital
maintenance work.
These problems are so bad that airlines like Iran Aseman, which just this year suffered
a crash killing all 65 passengers onboard, have been banned from flying to Europe.
With sanctions lifted, Iran airlines looked poised to buy 180 aircraft from Airbus and
Boeing to renew their aging fleets.
Updating our technology is our greatest tool in improving aircraft reliability and ensuring
the safety of our passengers.
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