Navigating Aeronautical Safety—Part 2

Unfortunately, the stories like the luck of JAL 907’s pilots are outliers in the quest to preserve lives aloft. Much more often, safety is purchased with the blood from hundreds of broken bodies inside the wrecks of crashed airframes.

The Bloody Triumph of Navigation

William Langewiesche’s story concerning the origins of CRM misses a huge fireball:

Tenerife took the lives of 583 human beings, the worst loss in aviation history. The world’s airlines (especially American and Dutch ones) were more than open to ideas about rooting out Clipper Skippers after the actions attributed to one Jacob Veldhuyzen van Zantens.

I feel compelled to point out some of the other lessons gleaned from so many killed in the Canaries. Chiefly the near-prohibition on stating the word “takeoff” on the radio outside the phrase “cleared for takeoff;” had the Tenerife controller given KLM 4805 his ATC clearance without using the word takeoff, perhaps Klaas Meurs or Willem Schreuder would have again notified van Zanten that they were not cleared to depart (or van Zanten himself could have noticed).

I will keep the focus on the controllers because eventually they were outfitted with a means to navigate their runways and taxiways more rapidly and shut down the van Zantens out there:

Since the rollout of Airport Surveillance and Detection Equipment (ASDE), controllers can “see” aircraft on taxiways regardless of actual visibility. More recently ASDE-X (which detects each airliner’s transponder on the ground) enables controllers to see a discreet tag on the ground radar screen, which in the future will permit FLL tower controllers to yell at errant United A320s without even having to look up.

But ASDE wasn’t developed in a vacuum. The road to CRM being mated with navigation equipment on the ground required the integration of the two aloft and in the regulatory sphere, an advance spearheaded from the deadly crashes of two widebody trijets that carried the same identifier.

The 191s

The highest fatality count from an airliner crashing into U.S. soil occurred at Chicago O’Hare International Airport on 25 May 1979:

American 191’s 273 dead spurred the extension of CRM beyond the cockpit. Lux, Dillard and Udovich weren’t given vitally needed information—the fact that the number one engine had detached (actual airframe separation is far more serious than loss of just engine power), the partial change in the position of the slats and flaps, and most importantly the total failure of the stall warning system on the DC-10. If the American pilots had known about one or more of the failures, those deaths likely could have been avoided.

Beyond the plane and its flight crew, light was shone on the Clipper Skippers in Tulsa. American 191 was primarily a maintenance accident, whose root was similar to the problems caused by autocratic captains in 1970s Pan American 747 cockpits. Grounding the DC-10 fleet and discovering the systemic problem (eight more aircraft had bulkhead cracks that could cause a similar engine separation) forced the FAA to adopt CRM in their enforcement duties, both over DC-10 operator maintenance and the manufacturer (recall the addition of additional stick shakers with redundant power sources along with hydraulic check valves).

The safety legacy of American 191 would eventually lead to American Airlines’ hometown of Dallas/Fort Worth six years later:

Delta 191 did not match its predecessor’s death toll, but the impact of the L-1011’s crash was even larger. Top-of-the-line airborne weather radars are one of the few expenses modern airlines often don’t skimp on; the risk of a horrific hull loss like the 1985 DFW L-1011 is just too great. Today not only are there microburst alerts warning of similar danger around major airports when the powerful downdrafts form, but the frightening power and the respect a pilot must give to the weather phenomenon is drilled during training from private pilot through ATP certification.

Amongst the integration of systems in fourth-generation airliners include windshear guidance, another system that at first appears to be automation (but isn’t—it too is navigation). Should the system detect the telltales of a microburst or other windshear event, an audible “windshear” caution message flags before escalating to full-on escape guidance. The pilot flying firewalls the thrust levers (commands maximum engine power) and either pitches up immediately or accelerates to a better climb-out speed first before pitching up (a circumstance such as encountering windshear on short final…such as the situation that Delta 191 faced). In this way the guidance can be lightly automated—fourth-generation computers can often tell if a speed increase is advisable more rapidly than the task-saturated pilots. But the maneuver is still manually flown; the expectation being that the pilots will exercise better judgment than the computers alone in a potentially deadly situation.

The legacy of the 191s is a dramatic drop in fatalities. It also answers a grievance airline pilots probably would nurse upon reading Langewiesche’s galling pronouncement:

In 1987, Airbus took the next step by introducing the first fly-by-wire airliner, the smallish A320, in which computers interpret the pilots’ stick inputs before moving the control surfaces on the wings and tail. Every Airbus since has been the same, and Boeing has followed suit in its own way.

These are generally known as “fourth generation” airplanes; they now constitute nearly half the global fleet. Since their introduction, the accident rate has plummeted to such a degree that some investigators at the National Transportation Safety Board have recently retired early for lack of activity in the field. There is simply no arguing with the success of the automation.

The A320 and its successors benefited enormously that the aftermath of the 191s had solved most of the issues facing air carrier safety…save for the elephant in the room:

The A320 is sometimes nicknamed derisively the Lumberjack, in homage to the performance of Air France 296 above. Automated fourth-generation airliners played no role in the mitigation of CFIT, as the Lumberjack of 1988 demonstrates.


One thought on “Navigating Aeronautical Safety—Part 2

  1. Pingback: Navigating Aeronautical Safety–Part 3 | In The Corner, Mumbling and Drooling

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