Despite occasional news of major airline accidents with fatalities, statistics continue to show that travel by air is very safe compared to other modes of travel. We use this data to convince ourselves to choose air travel when other options exist or to consider travel is an option when there is no other option.
I agree that Airline travel is safe, but this is a conclusion based on statistics rather than physical Truth. Making decisions based on the statistics of safe transport over a large number of flights is a great example of evidenced-based decision-making. The statistics of safe travel obligates us to choose air travel over other modes or over the option of not traveling. This obligation is explicit for business travel where airline travel for many occupations is as much a part of the job description as having a desk and a phone. We have been making flight decisions this way for decades so it predates recent big-data analytics that obligate new forms of decisions, but it is essentially the same approach. Based no statistics, not underlying truth, we can confidently make decisions.
Physically, airline travel is inherently unsafe. An aircraft cruising tens of thousands of feet above the surface is at peril of falling out of the sky. Human engineering of the aircraft results in a structure that is stable and controllable when operated in a multidimensional volume of parameters. Flight computers and pilot skill are very effective at keeping the aircraft inside this volume where the aircraft can operate safely. The statistics we have is confidence that human engineering, computers, and pilot skill can keep an aircraft from straying into a vast volume of parameters where the aircraft can not operate, and will quickly send the aircraft to the ground.
The recent tragedy of Air Asia 8501 is a recent example an aircraft entering this forbidden volume by some combination of weather conditions, instrument failure, and pilot error. I have limited understanding of exactly what went wrong, but it appears that the pilots lost control over the aircraft when it is several miles above the surface and despite that height and time advantage they were unsuccessful at ever regaining control. The aircraft entered the vast volume of parameters where the aircraft can not operate.
Aeronautical engineering teaches us that there are ways to build and operate an aircraft safely. This knowledge overlooks the problem that there are many more ways that aircraft can not operate. Pilots are trained to keep the aircraft in the volume of safe controllable operation, and they are trained to recover quickly when the aircraft strays outside of this volume. The latter training is very important. This fact is an admission that the previously safe aircraft can become very unsafe.
When an aircraft strays outside of its volume of safe operation, there is a narrow volume of time and actions that can return the aircraft to the safe volume. If the pilots fail to react correctly and in time, the aircraft will be in the vast volume where the aircraft can not operate at all and becomes as helpless as a falling feather in the air. For most conceivable configurations of aircraft with respect to the air, the aircraft will fall out of the sky just as surely as a rock would. This is what I mean about the unsafety of aircraft. Physically, the heavier-than-air mass of metal and cargo will fall to the ground at devastating speed in all about a very small volume of safe operation. A random simulation of different aircraft configurations and orientations in air will show nearly all to result in a crash.
In practice, crashes are rare. They are rare not because the concept of a heavier than air craft suspended in air is inherently safe. It is statistics of safe flights the prove that we have the skill and technology to keep the aircraft in its volume of safe operation.
When we make a decision that it is acceptable to fly, that decision is based on data, not physics. Certainly physics of aeronautical engineering and pilot skills contribute to the statistics. Physics tells us that heavier than air objects will fall out of the sky, and such objects include aircraft that are not in the proper configuration for safe flight. Despite the physics of the real risk of falling like a rock, the data over millions of flights assures us that the next flight will be safe. It takes an example like the Air Asia flight to remind us that aircraft are still heavier-than-air objects that will fall to earth.
My purpose of this discussion is to distinguish data from physical truth. Heavier than objects generally fall out of the sky. However, through engineering and training, we accumulate data that gives us great confidence that humans can control a particular type of object so that it always returns to earth safely. Certainly there is physics in the human engineering, but what finally convinces us is the data: the statistics of the safety over a long period of time. All mechanical forms of transportation employ physics in engineering and training. Airline travel in particular stands out as being particularly safe, not because of the physical truth, but because of the statistical evidence of actual observations.
I am using this as analogy to dedomenocracy. Dedomenocracy is a form of government where all policy decisions are based on statistics of observed data. In its pure form, dedomenocracy must exclude any human cognitive input, including model data from theories.
To counteract potentially misleading trends, dedomenocracy relies on frequent decision makings of short-lived rules where new rules have no obligation to honor precedents to be consistent with old rules. Every decision is based on the best data available at the time. In addition, the decision is based on nothing except this data. Human concepts of truth are not legitimate forms of data in a dedomenocracy.
When a dedomenocracy makes a decision to impose some new policy, it is just like our making a decision to employ airlines for our travel needs. We suspend our knowledge of what might go wrong by accepting the data that shows that those things rarely if ever happen.
Statistics shows us that aircraft do not fall out of the sky like rocks even though they are perfectly capable of acting like rocks as Air Asia 8501 reminds us.
Hypothesis Discovery 
While I was writing this post, there was another accident reported in France involving GermanWings 4U9525. In contrast to the AirAsia accident, it appears this flight was stable but descended into a mountain. The latest news is that one pilot was locked out of cockpit and remaining pilot was silent or incapacitated, based solely on voice data recording. So far, it appears that before hitting the ground, the plane was flyable but instead it had no one in control. There must have been an additional event that caused the descent that would not have been part of the computer flight programming.
Implicit in the statistical assurance of safe flight is that humans are in control of the plane. Planes are not safe without a pilot especially when configured to descend into mountains.
It is far to early to tell what happened in this flight, but it coincided with writing this post and gives another distinction of data from physics. The safety of flight is a statistical observation about human control over flying, not about inherent safety of the heavier-than-air object in the atmosphere.
Latest news on GermanWings 4U9525 is official announcement that leading theory is the lone copilot deliberately kept pilot locked out and deliberately crashed the plane. (Updated: I just read where some airlines have a procedure anticipating this by placing flight attendant in cockpit during a pilot’s absence so there is always two people in cockpit. This did not happen in this case).
From a data perspective, this is a rare but not unprecedented scenario. The data says that our collective experience over millions of flight hours is that flying is safe. The data tells us about human’s ability to control an aircraft physics to keep the plane from hitting the ground. It also tells us about human’s ability to master mental/psychological risks. Those risks are not eliminate by engineering or training.
When we say we trust the safety of flight, we are actually saying we trust the competent and good will of the pilots. Nothing in physics, engineering, or training assures flight is inherently safe.
As aside, I recall hearing that the flight safety statistics look best when measured in terms of incidents per passenger-mile. When statistics are recomputed in terms of passenger hours, the relative safety of flight looks less impress. The more time passengers spend under control of a crew, the more opportunity for the crew to make mistakes or to do something evil.
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