Thursday, February 26, 2009


I was working on a project at work and was describing a problem I observed to my office-mate and he responded to me "P-I-O", as if I should know what that meant. I gave him a blank stare. The term comes from his background in "Flight Controls". He then explained to me what "P-I-O" stands for.

PIO = Pilot Induced Oscillation

Basically, PIO occurs when there is a delay between the flight control stick and the reaction of the airplane.

Pulling the stick back makes the nose go up, pushing it forward makes it go down. The movement of the aircraft is proportional to how far the stick moves. This is where the problem starts. These are the steps:
  1. The pilot moves the stick a small amount.
  2. Because of the delay, they don't feel a response, so they push it a little more.
  3. The airplane now starts responding to step 1.
  4. The pilot feels the response and moves stick back to the center.
  5. The airplane responds more due to step 2.
  6. The pilot feels the increased response and feels compelled to cancel it by pushing the stick in the opposite direction.
  7. The airplane slows movement due to step 4.
  8. The pilot feels no response so pushes the stick more.
  9. The airplane now starts a delayed response to the pilot's reaction.
  10. Each time, the pilot reacts more, resulting in an oscillation, thus "pilot induced oscillation" (I challenge you to find a better name)

The following videos are good demonstrations of this effect. At the end I explain what they should have done and how this relates to life ;-)

How can this be avoided?
After making the first small movement, the pilot should intuitively know the delay and wait for a response. His response has the delay built into it. This comes from training and self restraint in panicked situations.

How does this apply to you, even if you will never pilot an airplane?
  • Much of our life involves "actions" and "reactions" or "consequences".
  • Some of these actions are limited to one dimension (left/right, up/down, more/less, harder/softer, etc.).
  • Many "reactions" are delayed from the "actions".
  • These delays can result in us to overreact.
  • Overreaction results in instability.

Here are some examples:
  • A person responds to strict parents by being overly lenient with their children.
  • The same thing, but lenient parents result in being overly strict (because you know how much your kid's are getting away with).
  • The same thing, but with spending money vs. being thrifty.

What's an extreme example?

Our national government. The delays are years and decades, but our "pilots" show no constraint and ALWAYS overreact. What is the promise of every candidate? Change. But instead of slowly moving the stick back to center, they thrust it full throttle in the opposite direction.

The result is the Democrats spend hundreds of billions of dollars on their favorite causes. The Republicans then spend a trillion dollars on their favorite programs to redirect the course of our nation. The Democrats feel now feel obligated to spend trillions to redirect the course. The videos show how this ends up. PIO ain't pretty.


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