Content provided in partnership with

Government Industry

The Never Ending Story — Going to Even Greater Lengths to Prevent Take-off Overruns

Air Safety Week, July 17, 2006

A 30-Hour Day Defense Mechanism

The part that fatigue had played in setting the scene for the Halifax 747 freighter accident was evident in the TSB's discovery that 71 percent of MK flights on the route had been planned to exceed 24 hours duty time. Twenty-four hours was the maximum allowed for a "heavy" crew under the Ghanaian registered MK's own operating manual. Indeed, had the Flight MKA1602 crew gotten airborne, their cumulative duty time would have been over 30 hours.

Most Popular Articles in Business: Research and Markets : Tesco Plc - SWOT Framework Analysis; Do Us a Flavor - Ben & Jerry's Issues a Call for Euphoric New Flavors; eBay made easy: ready to start an eBay business? These 5 simple steps will ...; Katrina's lawsuit surge: a legal battle to force insurers to pay for flood ...; Wal-Mart's newest distribution center opened last month near the southwest ...; More »

The TSB's call for a takeoff safety device to alert crews to a difference between expected and actual takeoff performance was echoed by the Air Canada Pilots Association Chairman Brian Boucher. (see ASW, Nov. 1, 2004 for discussion of a take-off performance monitor - TOPM). Boucher also says Canadian regulations that currently allow crews to fly up to 20 hours need to be revisited, to effectively manage the risk of fatigue. The TSB Report cites instances where patently incorrect data had been entered into passenger jets' FMS (Flight Management Systems), leading to some very close calls. Wendy Tadros, TSB's acting chair, said inputting errors are a "pervasive problem" worldwide. "We believe we need an additional line of defense -- a mechanism to catch the unexpected errors," she said.

The Takeoff Performance Monitor

Pilots do have an innate tendency to implicitly trust computer outputs. Indeed, it is hammered into ab initio pilots to "always trust their instruments" (see ASW April 25, 2005 "The Airline Machine Minder" and ASW January 10, 2005 "A Nonpareil Year for Safety"). But there has proven to be too much scope for undetected human input error in automated processes, so the industry will now seek a new insurance. The TSB found there to be two separate problems:

* The failure or absence of procedural defenses to detect an error in the takeoff performance data; and

* The failure of the crews to recognize abnormal performance once the takeoff had commenced.

Whatever the last-ditch solution is to be for underpowered or misconfigured takeoffs, it would have to be user friendly and early warning. Progressive takeoff roll data could be presented to the pilot in a readily interpretable form for situational awareness. It can be a single white LCD digit in a separate prominent display, adjacent to the airspeed indicator, which will illuminate after a standard trigger distance (perhaps after 3,000 feet of wheel- spin). If it shows zero, you are "on the money". If it indicates +1 (green) you are lighter than you thought, it's more humid or the temperature has suddenly dropped. If it shows -1 (amber) you are heavier etc.; -2 (amber) and you are worried (it has your attention); drops to -5 (red/flashing) and the decision that "discretion is the better part of..." is already made for you and it's made in time, and so you reject your takeoff early.

This decision aid would add technological logic to what a pilot must instinctively do now: monitor the progress of the takeoff run and determine whether it "feels" right or not. The difference is that it would add confidence and a quantifiable precision to a seat-of-the-pants process. It would work just as well in cold dark places, in rain and snow and other cases where the crew's sensory perceptions may be constrained or illusions present (such as humps in the runway). It should not be a distraction because the display could be keyed to just disappear once the nose-gear oleo extends upon rotate.

Getting something wrong now and again is human nature. Allowing that error to create a calamitous accident chain is bad risk management. TOPM is "doable" within existing technology. Such a "Take-off Tattle-Tale" could easily be integrated into present aircraft electronic systems.

Government Industry

The Never Ending Story — Going to Even Greater Lengths to Prevent Take-off Overruns

Air Safety Week, July 17, 2006

Find Research Guides for:

Find Featured Titles for: Arts

Most Popular Articles in Business

Most Popular Publications in Business