Building contingency

Building contingency

Jason George shares an article that explores building contingency at the cost of agility, and why taking the safe route may be more costly. 

The next time you travel by airplane, look out the window and see if you can count how many engines are attached to the wings. Chances are pretty good you will find only one on each side. This holds true even on routes with long stretches over water or harsh terrain that provide no suitable diversion sites in case of mechanical trouble.

With few exceptions, most jets in commercial service now come fitted with two engines, a notable change from the status quo in the middle of the 20th century. In those earlier days of air travel the norm was to have four, and not because they provided the optimal ratio of power or efficiency. The main reason for this redundancy was the perceived unreliability of existing engines.

If there were only two to begin with, a blown piston or other mishap would leave just a single engine operating, a prospect too risky for regulators. This led manufacturers and their airline customers to converge on four engines as the standard. (For obvious reasons of symmetrical thrust an odd number wasn’t a popular choice, although some models featured a third engine embedded in the tail.)

What’s more, regulatory bodies like the Federal Aviation Administration in the U.S. mandated that aircraft couldn’t stray too far from possible landing sites, in case of emergencies requiring immediate help from the ground. This meant routes were carefully plotted not to take the shortest distance between origin and destination but to stay within range of potential diversion airports throughout the flight.

Key points include:

  • The great circle route
  • Known unknowns
  • Getting rid of the safety net

Read the full article, Calculated risks and the costly status quo, on