The crash of Germanwings Flight 9525 in the French Alps sent a chill through our bones and served to remind us of the inexorable law of probability that sooner or later, another one of aviation’s finest would attempt the unthinkable.

Again we are at grips with the indisputable fact that the flying public is only as safe as airline employees are sane. Hearts go out to the victims’ families and to the brave recovery workers investigating the crash site. Nobody pretends their work is just another job.

Flight attendants and pilots are no different than other groups in the workplace. They sustain a normal average of both good and bad, perhaps even harboring a cold-blooded killer or two which, in the context of what just happened, would not require much of a stretch to imagine.

After 9/11, it drove me to distraction that ground personnel were allowed access to the airport through the employee parking lot without having to pass through security screening. I could have easily smuggled a gun onto the airplane by planting it in a secure area in advance of the flight, clearing security at check-in as an outbound working crew-member, then retrieving the weapon in time for departure.

The Association of Flight Attendants lobbied in vain to have this gaping security loophole closed.

The Federal Aviation Administration mandates that two crewmembers must be on the flight deck at all times. Even then, it’s far from certain another crewmember could have prevented the crash of Germanwings Flight 9525, but at least there might have been some chance of a successful outcome.

As it was, all alone in the cockpit, in full control and without perceptible strain, the co-pilot had cushioned time to execute his sinister plan with lethal effectiveness.

Supposing the situation provisionally resolves itself in the flight attendant’s favor. What then? With an ominous mountain looming into view, a look through the cockpit door’s peephole would undoubtedly reveal a violently agitated pilot pleading to get in. Flight attendants are not trained to operate the switch that overrides the door’s locking mechanism, if they even know one exists. With time of the essence, its location and operation should be second nature. Making it a part of every flight attendant’s annual emergency equipment training is a no-brainer.

With no protocols in place to evaluate the mental health of their employees, airlines lack dexterity at flushing out internal trouble. I wasted plenty of energy containing the onboard mayhem of a few. More often than not, fearing a lawsuit, the company looked the other way. I had to literally beg a base director to ground one dangerous alcoholic with anger-management issues. When the person in question opted for early retirement instead of mandatory rehab, the base breathed a communal sigh of relief, prompting one colleague to remark, "With flight attendants like that, who needs terrorists?"

Lives depend on crewmembers’ sound judgment. We need them at their sanest and most effective as safety professionals, where they feel responsible for their actions, for each other and for us.

Airlines have been so focused on the outside threat that they’ve overlooked the obvious threat from within. Andreas Lubitz should have been nowhere near an airplane. An ex-girlfriend, a Germanwings flight attendant no less, called him troubled and tormented. The warning signs were there, but nobody wanted to read them.

Employees have a duty to speak up when they fear all is not well with the balance of a co-worker’s mind.

Another Germanwings tragedy is just too dear a price to pay for silence.