| We've all heard the old saying that, because auto | | | | a Boeing 737, where recovery from a roll that results |
| accidents are more prevalent than aircraft accidents, | | | | from a fully deflected rudder is not possible unless |
| flying is safer than driving. What this statement | | | | attempted at above "crossover speed", the problem |
| ignores, of course, is that aircraft accidents are | | | | with this decision was that, by pulling up on the yoke |
| invariably more fatal than auto accidents. The best | | | | and increasing crossover speed, the pilots also |
| way for pilots to avoid flying accidents is to | | | | increased the plane's angle-of-attack, which |
| participate in upset recovery training, where they | | | | decreased roll control. If the pilots had pushed the |
| learn numerous techniques and maneuvers for dealing | | | | yoke forward, reducing angle-of-attack while gaining |
| with a variety of unanticipated aircraft disturbances. | | | | airspeed, they may have gained enough lateral |
| But even after pilots receive upset recovery training, | | | | control to counter the roll. |
| they can still increase their knowledge of upset | | | | The second questionable piloting decision involves the |
| recovery by studying situations where upset | | | | plane's increased angle-of-attack. By pulling back on |
| recovery went wrong, an fine example of which | | | | the yoke to increase crossover speed, the aircraft's |
| occurred on September 8, 1994, when USAIR Flight | | | | angle-of-attack increased to such a degree that it |
| 427, a Boeing 737-300, plummeted to the ground on | | | | caused the plane to stall. When a plane stalls above |
| its way to Pittsburgh International Airport. | | | | its critical angle-of-attack, lift decreases as drag |
| The cause of the accident was attributed to a faulty | | | | increases, making the plane increasingly difficult to |
| rudder power control unit, which caused the rudder | | | | control. Further compounding the problem was what |
| to fully deflect to its "blown down" limit. On its way | | | | is known as "negative damping in roll", which occurs |
| to the airport, the 737-300 experienced wake | | | | when a stalled wing's angle-of-attack increases, |
| turbulence from a Boeing 727 that flew ahead. The | | | | causing the wing to drop and increasing the plane's |
| 737-300 rolled to the left and the co-pilot attempted | | | | yaw in the direction of the stalled wing. |
| to roll back to the right. But instead of becoming | | | | Ultimately, the pilots of Flight 427 were at the mercy |
| level, the plane yawed to the left as a result of a | | | | of a rare mechanical failure, but this is exactly the |
| fully deflected left rudder. As the plane rolled further | | | | kind of situation that upset recovery training, which |
| to the left, its nose continued to drop. Six seconds | | | | the pilots of Flight 427 undoubtedly possessed, |
| after the rudder became fully deflected, the plane | | | | intends to make survivable. The pilots displayed solid |
| stalled, making it nearly impossible to control. A few | | | | recovery attempts during a yaw and roll that can |
| seconds later, the plane impacted the ground. | | | | happen to any aircraft for a number of reasons, but |
| In looking at what went wrong with Flight 427 from | | | | their situation possessed mitigating circumstances |
| a piloting perspective, two things stand out. First, the | | | | that were likely not simulated during their upset |
| pilots pulled back on the yoke in an attempt to bring | | | | recovery training. That's why studying aircraft |
| the plane's nose level with the horizon. In the case of | | | | accidents is a valuable asset to learning to fly safely. |