‘Safety Planes’ and Aviation Conservatism

We may think aviation is modern and progressive but outside of avionics, the electronic systems, it’s profoundly conservative, especially for light general aviation (GA) planes.

Since the post-WWII boom years ended airplanes are not mass-produced and light GA still operates largely with venerable antiques from the Truman era; and with Cessnas, Pipers, Beechcrafts, Mooneys, etc. built in small batches since.

ERCO-415D-HB-ERB-Ercoupe_airplanemartdotcom

The FAA requires a Supplemental Type Certification (STC) to make any substantial change to certificated aircraft to ensure that the expensive, heavily regulated construction is not compromised.

If you build your own aircraft you may experiment all you want but the plane cannot be used commercially and will still need to be inspected and approved by the FAA even if certificated in the Experimental category (though most homebuilts are based on conventional technology and are experimental mostly in name).

wikipedia_heading_indicatorPilots have a healthy regard for their own skins and tend to trust methods, materials and technology that have been proven through the years.

Thus we fly planes built mostly using welded steel  tubes like a WWI Fokker, or 1930s era monocoque construction, with air cooled, magneto-sparked, ‘boxer’ type engines similar to old Volkswagens.

Radio communication equipment has not advanced past the VHF radio spectrum, using AM, prone to static and interference and wastes transmission power.

To find direction we must use the magnetic compass, invented in China between the 2nd century BC and 1st century AD, error prone for aviation. Even the more modern, though still old, heading indicator must be reoriented every 20 minutes or so using the ‘whiskey compass’.

Our depression-era Continental and Avco Lycoming engines still largely use carburetors, supplanted by fuel injection for ground vehicles since the 1980s because of the carb’s poor atomization, inability to alter mixture precisely according to engine conditions, high emissions, etc.; so accidents still happen from carb ice.

gaaccidentsbytypeLSA and smaller planes, due to light construction, gust sensitivity, weak powerplants, etc., have never been very safe, especially when compared to jet airliners.

This chart shows accidents and fatal accidents per 100,000 hours of flight time.

Notice the rate for single-engine piston planes, 7.91 with 1.41 fatal, compared to jet aircraft, 0.97 per 100,000 hrs with 0.56 being fatal.

 

Having two engines doesn’t help much and actually kills more than single-engine craft.

And even the poor piston accident rate is dwarfed by rates for homebuilts, rotorcraft, gliders and balloons, though gas bags don’t seem to kill anybody, perhaps because of the slow landing speeds.

gaaccidentdistbyoperation
Here is the breakdown for GA fatal crashes by type of operation ending in 2003. Personal and business flying is the least safe type operation even compared to crop-dusting.

cause_enWho or what is responsible for this abysmal showing by general aviation? Over half were caused by flight crew errors such as stall/spin and controlled flight into terrain; nearly another third were caused by weather and aircraft malfunctions.

This poor safety record is not a new phenomenon and even in the 1920s and ’30s there were government and private initiatives to improve flight safety by making the aircraft easier to fly and resistant to stalls and spins.

In Beware the ‘Safe’ Airplane Richard Harris detailed several attempts and why they failed. Like the Piper Cub, everybody’s favorite with gentle flying manners and low stall speed. Yet the Cub’s accident record is not good at all, in terms of both having an accident and surviving it. Harris says “Yes, the Cub definitely can — and may — just barely kill you.”

The Ercoupe, he says, “heavily sold as “The World’s Safest Airplane!”, turns out to have one of the highest crash and fatality rates of modern light aircraft, per seat-mile flown…even scored badly in crashes listed under troubles it was supposedly immune from: stall/spin crashes (worse than Bonanzas and Mooneys) and groundlooping (worse than the Piper Cub)!”

The “unstallable” canard-wing;  slots and limit-travel elevators; gyrocopters; two engines; tandem-engine; Aero Commander & Aerostar; parachutes; Glass Cockpits; None panned out in terms of safety.

What Harris says we really need:
Reliable engines;
Stout, forgiving landing gear;
Moderate airfoils that handle stalls well;
Long wings and tails that spread out forces, leaving a plane less vulnerable to turbulence and less twitchy in control;
Robust airframes (and even seats) that survive and absorb impacts;
roll-cage structures;
Good glide-ratios and slow descent rates — combined with low stall speeds — to give pilots more options and control in dead-stick  situations;
Maintenance affordability, accessibility and ease, and low-maintenance design; …and even…basic cockpit ergonomics.

HowSafeIsFlyingChartI’d like to end with a table showing the safest and most dangerous of the old LSA types available to us but statistics are not available, or my web search skills have declined.

I know the Cessna 172 and smaller 150/152 types are very safe, while Piper Super Cubs not so much-but those don’t qualify as LSA. But then safety is a relative thing as the chart above shows.

There IS a safe light plane. It’s the one on the ground — tied firmly to the earth, or locked in a hangar. All others are risks to be selected and managed with care. Richard Harris

Some interesting links: Flying Mag, May 06, 2009 bashing LSA safety record; Phillip Greenspun on flight safety, 2002; AOPA table showing improved flight safety through time, 2009; planecrashinfo.com interesting airliner plane crash stats site.

Ercope photo courtesy airplanemart.com
DG image courtesy Wikipedia

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