Let me begin by affirming that I am a great admirer of Ms. Deborah A.P. Hersman, the Chairman of the National Transportation Safety Board (NTSB). It seems to me that she well understands the power of moral suasion at her agency's disposal, and she makes good use of the bully pulpit that her office provides.
Given my admiration of her, I was taken aback and disappointed when, in her opening remarks for the Board's recent forum on Professionalism in Aviation, Ms. Hersman said this:
"[T]he American people rightly demand not 99-plus percent safety, they demand 100% safety."
Of late, we are daily reminded that we engage as a society in high-risk endeavors. Whether we are speaking of an aviation mishap or a major casualty in some other technology-intensive field, we understand that some combination of carelessness, incapacity and neglect tipped the balance from "ops normal" to catastrophe. The systematic defenses that had been designed to save the day were overwhelmed. And people died.
Predictably, the cries for safety ring out across the land. Managements and regulators are faulted because they failed to ensure that the operations were safe. We must be able to assure the public that they will be safe! Tell me, please, what does "safe" mean?
The dictionary teaches that "safe" means "secure from liability to harm, injury, danger, or risk." So, to render an activity safe, must we reduce the "liability to harm, injury, danger, or risk" to essentially zero? Is that to be our goal?
"A ship in harbor is safe, but that is not what ships are built for."
-- John A. Shedd, educator, Salt from My Attic, 1928
If, in our economic activities, we are to venture out of the harbor and onto the stormy seas of real life, we have to realize that there will be risk, there will be danger, that we shall go in harm's way. We cannot be safe.
Let me repeat that: We cannot be safe! Ever! To live, is to live with risk. To "demand 100% safety" (in Chairman Hersman's words) is to be at best naive and at worst a fool.
"Insisting on perfect safety is for people who don't have the balls to live in the real world."
-- Mary Shafer, NASA Dryden Flight Research Center
If we will wrap our minds around this simple, somewhat discomforting truth, perhaps we can abandon the fallacy of safety and start to think seriously about risk mitigation. To live in the real world, we need to understand the sources and magnitudes of our risks. We need to think through ways to avoid or to counteract them. And we need to so order our lives that adequate countermeasures will be at hand whenever danger looms.
Risk mitigation is always purchased. We must decide how much of it we wish to pay for. The calculus, whether explicit or instinctive, involves evaluation of the likelihood of mishap and the cost of consequences.
When the potential cost of failure is very high (say, a nuclear plant core melt-down) there is almost no limit to the risk-reduction budget. When the cost of failure is less extreme (as with aviation systems, where at worst a few hundred people are at risk) then we will spend a lot to reduce risk, but not an unlimited amount. We just can't afford to reduce risk in aviation to the level where it must be in nuclear systems.
Once the calculus of risk mitigation is completed and appropriate safeguards are in place, it's essential to avoid deviations that introduce unmanaged risk factors. There are always pressures, economic and political, to allow a risk in "just this once". And then if no mishap occurs, well, it must be all right to accept that risk routinely. That's called "the normalization of deviance," and we lost two space shuttles that way in spite of supposedly nuclear-quality risk management systems.
When the public asks of us, "Is aviation safe?" we can't honestly say, "Absolutely!" We have to answer: "We understand all of the risks and we take measures to deal with them. And we work every day on doing it better." And it has to be the truth.