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This question was raised as part of this discussion.

Why are accident rates higher on smaller aircraft?

It seems the safety record of military, private and small commuter planes is much less safe than that of large commercial operations and I was wondering what factors cause this?

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    $\begingroup$ This seems a bit broad to me as military, private, business, and airline operations are very different, as are the types of small planes they fly. $\endgroup$ – fooot May 4 '18 at 14:23
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    $\begingroup$ @Cloud have you considered therapy for your phobia about flying? It seems to be causing you much unhappiness and it doesn't need to. $\endgroup$ – zeta-band May 4 '18 at 14:46
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    $\begingroup$ @zeta-band Hi, thanks for the suggestion. What type of therapy? I have thought about doing a fear of flying course through an airline if that might help $\endgroup$ – Cloud May 4 '18 at 15:23
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    $\begingroup$ @Cloud The Mayo Clinic has a page on general therapy for phobias. You will have to find a resource in your location that can help with with specific treatment. $\endgroup$ – zeta-band May 4 '18 at 15:57
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The amount of resources that go into commercial aviation are really amazing -- the amount of time, talent, money, and effort that have gone into making the airlines the safest mode of travel known to recorded history is really extraordinary, and the results reflect that.

Design

Aircraft are expensive, but a part of that expense is the extreme care that has been taken to make them highly reliable, with redundant systems and lots of advance warning systems when something is nearing the point of failure.

Fifty years ago, aircraft were less reliable; the engineers have incorporated the lessons learned. And, considering how much money an airliner make, airlines are generally willing to pay absolutely top dollar for the very safest design possible.

Small aircraft have also benefited from this learning process, but as a matter of economics, they don't get quite as much redundancy or refinement. While 99.999% might be "good enough" for the general aviation, the airlines can afford the (high) costs of adding more 9's onto the end of that number.

Maintenance

Again, the airlines can afford a maintenance process and inspection regime that would raise the cost of flying a light aircraft significantly.

Mechanics are trained to uniform standards and work in a carefully monitored environment where parts are exactly tracked and the aircraft have an incredibly detailed history of all that's been reported and fixed over their lifespan.

Manufacturers like Boeing and Airbus can see millions of hours of data and spot trends that are developing to head off incipient problems before they become widespread. This, combined with the way that the aircraft are engineered, makes things really, really reliable.

General aviation maintenance is good -- I'm not bashing that -- but airline maintenance, especially at the major airlines, is amazing. That's not free, but the results are there.

Pilot experience and training

Light aircraft are often flown single-pilot, by a pilot who probably has under 2000 hours, and who may have flown 200 hours in the past year.

On the other hand, airline pilots are typically hired with at least 1000 to 2000 flight hours, often more, and a captain at a major airline may well have 10,000 to 20,000 hours. Added to that, the crew has probably flown between 400 to 800 hours in the last year, as well as getting multiple days of training -- both ground school and simulator -- as well as at least one if not two checkrides.

Flying is their profession, not a hobby, and they spend time continuously studying the aircraft, its systems and checklists, the environment, and the regulations. And, they're trained to work as a crew -- if one pilot is about to make a mistake, the other pilot is there to catch it and keep things on track. Not everybody flying light aircraft has these resources.

All of this is possible because, while it is all expensive, airlines can afford it.

And the records speak for themselves -- one fatality in a commercial U.S. aircraft over the last several years -- which includes many millions of flights. I don't think any other human activity -- including sleeping in your own bed at night -- can claim a similar safety record.

The relevant point isn't that light aircraft flying is "dangerous" compared to commercial aviation; it's plenty safe by normal comparisons. It's just that airline flying is so incredibly safe, any other activity will look more risky in comparison.

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  • $\begingroup$ Excellent answer, thanks. $\endgroup$ – Cloud May 4 '18 at 16:17
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    $\begingroup$ "to include sleeping in your own bed at night" I'd like to see the statistics on that one. Also some joke about crew resource management or sterile cockpits... $\endgroup$ – user28387 May 4 '18 at 16:33
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    $\begingroup$ @PhotoScientist If we all live to 90 years old, having slept 8 hours per night, and then one passes away peacefully in the middle of the night, that is about 1 death per 262,000 person-hours spent in bed. One million flights is probably over one hundred million passenger-hours, so ... yeah. Some may joke about CRM, but after 2+ decades of studying & using it in crew aircraft, I will say quite confidently that it works well. $\endgroup$ – Ralph J May 4 '18 at 17:05
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    $\begingroup$ @tonysdg I would venture a guess that flying across the US is significantly safer than walking that same distance, and similarly, that hopping a flight from England to France is significantly safer than trying to swim the channel. And I'm not even factoring in the time; just "will you reach your destination alive." $\endgroup$ – yshavit May 4 '18 at 19:49
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    $\begingroup$ @PhotoScientist: Haha alright, I admit defeat :) With my sister being an aerospace engineer, I really should know better than to make jokes with aviation enthusiasts ;-) $\endgroup$ – tonysdg May 4 '18 at 20:58
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Another factor: commercial airliners tend to fly at high altitudes, over most bad weather and conditions of poor visibility for most of their flight time. Light planes are typically unpressurized, with a ceiling of 12,500 feet (up to 15k feet for short periods of time), which puts them in the conditions of bad weather or poor visibility, not only during takeoff and landing, but for most of their flight time.

The majority of light plane crashes are weather and visibility related... typically a VFR pilot flying into IFR conditions, becoming disoriented due to poor visibility, and crashing... such as the JFK Jr crash.

Commercial flights don't tend to have this happen, partially because the pilots are trained in IFR flying so they're less prone to spatial disorientation when they can't see the horizon, partially because they have the experience and the equipment/information to detect and avoid really bad weather, and partially because they're usually flying over most bad weather and conditions of poor visibility, not in them.

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Large commercial flights, two engines, two pilots. More eyes and hands to handle loss of an engine. Very high recurrent training standards mandated.

Owner flown and other private pilot flights, it's usually attributed to lack of training. Flying into IFR weather without the rating, or practice, or equipment (think icing conditions). Or fuel exhaustion. Much less training after an initial license, or add on rating (instrument, maybe commercial, maybe other plane types. For example, mine stopped after the instrument rating, and I only flew my plane, so I just became really proficient in it).

Medium to large Business, they typically have professional pilots flying the plane. Small business might have the owner as pilot and I'd have to see stat's on their accident rate. I bet the rate is pretty low.

Then there's things like helicopter conducting sight seeing tours over the Hudson River in NYC. I think that was mechanical failure.

Military - I believe that outside of war theaters, the accidents usually occur during training, and they do a lot of it. Fly enough hours, and something is bound to break, or an unrecoverable situation occur, or just plain human error occur.

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  • $\begingroup$ Don't forget auto pilot. And can't ATC land some planes from the tower? $\endgroup$ – Mazura May 5 '18 at 17:17
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    $\begingroup$ @Mazura - no, not at all. ATC is like a traffic cop, but the driver still guides the vehicle. $\endgroup$ – nexus_2006 May 5 '18 at 17:49
  • $\begingroup$ Small planes (my definition of small, 2-4-6 seats, vs FAA definition, which is anything up to 12,500 lbs) have autopilot as well. Avionics in small aircraft can be pretty advanced. Affordable Flight Management Systems (FMS) give us the same capability as the big iron. Only thing missing is the autoland in zero-zero conditions, and capability to land in 50 and 100 foot ceilings. The larger small planes are often flown commercially and may be better equipped for the lower ceiling approaches. We with IFR ratings have to fly a minimum number of approaches to stay current to able to file IFR. $\endgroup$ – CrossRoads May 5 '18 at 22:40
  • $\begingroup$ Simulated terrain views based on GPS position and altitude is also becoming common, mimicking the infrared views found on more expensive planes. Bigger planes may have radar too for better avoidance of weather. $\endgroup$ – CrossRoads May 5 '18 at 22:43
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For general aviation, it's mostly the higher probability of accidents caused by bad judgement; flying VFR into IFR, running out of gas, overloaded takeoffs, incompetent handling close to the ground, etc. Whereas the airline world is highly regimented and operates on clear go-no-go criterea, with backups of backups both system wise and procedurally. When I was bush flying on floats, the dangers were mostly due to the need to make constant judgement calls on weather and loads etc. It's a world of greys, not black and white and of living by your wits. Very challenging but loads of fun.

Anyway, filter out all the GA accidents caused by incompetence and poor airmanship, and I believe you start to approach the safety of airline flying. Because if you are in a Chevy Biscayne of the sky like a Cessna 172, that is halfway well maintained, on a sunny day, full of gas, and you have some minimal level of good skills and judgment, you really really have to work at it to kill yourself.

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  • $\begingroup$ Why is running out of gas so common? I mean, people don't do it in cars very often so how it happens so often in private flight? $\endgroup$ – Cloud May 4 '18 at 16:21
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    $\begingroup$ @Cloud: I think it happens more than you think in cars. It's just that the consequences aren't as newsworthy as they are with airplanes. $\endgroup$ – Fred Larson May 4 '18 at 16:52
  • $\begingroup$ Typically a light plane flies into conditions of poor visibility, such as fog or rain, and runs out of gas trying to find an airport with good enough visibility to land. Unlike airliners, light planes don't have the equipment, nor does the pilot have the training, to use the Instrument Landing System that guides airliners to a landing in bad weather. Also, inexperienced pilots are slow to even detect an emergency situation, let alone declare one to get the help to get down safely. $\endgroup$ – tj1000 May 4 '18 at 17:21
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    $\begingroup$ Light planes DO have Instrument Landing System equipment. We just may not be able to make it down to 50 feet, or have autolanding, like the big iron boys & girls can. For example, the lowest I can go is 200 feet above runway height, if I'm not out of the clouds by then I'm going around to try again, as conditions do change, or I'm going elsewhere. $\endgroup$ – CrossRoads May 4 '18 at 17:27
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    $\begingroup$ @CrossRoads I don't think the answer was meaning to say that light aircraft don't have ILS equipment, but rather than non-IFR-rated pilots flying into IMC is a significant cause of death (which is true.) $\endgroup$ – reirab May 4 '18 at 17:49
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All aircraft and pilots must meet certain standards to be deemed fit to fly. For example: all parts used in an aircraft (general, commercial, or military) must have accompanying documentation attesting to their fitness for use in an aircraft - traceability to point of manufacture, inspection, etc.. Aircraft used in commercial transport do require more frequent inspection than general aviation, but that shouldn't make general aviation less safe. Commercial pilots require more frequent medical examinations, require periodic "check rides" and generally end up more closely monitored for proficiency than private pilots. Also, commercial pilots tend to accumulate far more flying hours, so commercial pilots are usually more experienced than private pilots. That said, commercial pilots always start out as private pilots. General aviation aircraft far outnumber commercial aircraft; there are far more general aviation aircraft movements than commercial aircraft. Military aircraft have to operate in hazardous conditions - combat aircraft have to be flown to the edge of their flight envelope to gain a tactical advantage and/or escape a threat; even military transport sometimes have to be operated at their extremes to either get in and out of tight and/or unprepared places or avoid becoming a target. This sort of flying must be practiced regularly so that the pilots get it right when it matters most, so military flying is often riskier than non-military, even in peacetime.

So,

A higher incident rate among general aviation can be attributed to sheer statistics - just more of them around, and also to a lower level of pilot skill, experience, or discipline.

A higher incident rate among military aviation can be attributed to the extremes to which plane and pilot have to be pushed, and the greater likelihood that either/both will from time to time be pushed a little too far.

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  • $\begingroup$ You have some useful points here, but "more flights inevitably equals a higher accident rate" isn't really accurate. Aviation accident rates are often given per 100,000 flight hours, for example, which allows you to compare rates in commercial vs. GA regardless of the occurrence (the absolute number) of accidents. $\endgroup$ – Pondlife May 6 '18 at 15:37
  • $\begingroup$ @Pondlife Good point. Flight durations probably are longer for commercial flights than general aviation, on average, but most accidents/incidents occur during or around takeoff and landing than during cruise. Since general aviation likely performs more takeoffs and landings per flight hour than commercial, it would be reasonable to expect that takeoff and landing related accidents would be higher per flight hour for general aviation than commercial even if rates per movement were the same. $\endgroup$ – Anthony X May 6 '18 at 19:49

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