Brakes and Contact!” After calling out these words and hearing them repeated back from the cockpit, an intrepid aviator standing at the nose of a classic old aeroplane smartly whips the prop downward, and the engine roars to life. So romantic. So classic. So dangerous if you don’t know what you’re doing.

Even though you (probably) don’t hand prop a SPAD XIII on the regular, you still have to come into close contact with props as part of every preflight inspection—or at other times, such as when pulling an aircraft without using a tug.

We’ve been taught that all propellers should be treated as live (i.e., ready to spring to life) with just the smallest movements. Yet, prop versus human accidents continue to occur through moments of forgetfulness born of routine, distraction, or poor communication.

The investigations that follow and the conclusions they draw remind us that many, if not all, of these incidents are preventable. They result in life-changing injuries or worse. Just last month, a woman in Kansas was tragically killed after backing into the operating propeller of a skydiving aircraft.

The risks of prop strikes come in two broad categories.

1. A stationary propeller springs to life and strikes someone.
2. A propeller that’s already turning strikes someone.

Let’s address the former first.

Common reasons why idle props spring to life

• A hot magneto created by a fault or improper grounding provides a spark that ignites the fuel when the propeller is moved.
• A faulty ignition switch is broken or stuck in the START position.
• Improper shutdown when a pilot forgets to turn off the magnetos, resulting in a spark that ignites residual fuel in the cylinder combustion chamber.
• A pilot intentionally starts the engine. We shout “Clear Prop!” for good reason, but incidents still occur when that critical phrase isn’t heard in time (or at all).

Best practices for general prop safety

Always assume that the propeller can spin at any moment. If you’re running your fingers along the prop during preflight, position your body weight and feet carefully, and be ready to get away quickly, just in case.

Before approaching the prop, confirm that the magnetos are off and the keys are out of the ignition and in your pocket. If feasible, be sure the prop area is clear before turning on the master switch, just in case the starter circuit is closed for some reason.

Maintain a clear zone around the propeller whenever the aircraft is running, and avoid the temptation to make last-minute checks on the ground once the engine is on. It’s a pain, but if you need to check something outside, turn the engine off first.

Get and stay on the same page as everyone outside the airplane. Be sure to wait a few seconds after loudly yelling “Clear prop!” out an open window (if allowed by the POH) before starting the engine.

Best practices for hand-propping

Hand-propping requires additional layers of safety measures. The FAA makes that abundantly clear in the Airplane Flying Handbook when it states that “hand propping an aircraft is a hazardous procedure when done perfectly."

But if you fly a vintage airplane with an “Armstrong Starter" and your personal minimums allow you to proceed, then be sure to fully absorb and follow Chapter 2 of the Airplane Flying Handbook, from which the tips below were sourced.

• Have a qualified person who understands the procedure in the cockpit to manage the controls, receive direction from the person managing the hand-propping, and communicate back.
  
  
• Keep the chocks in place to prevent the aircraft from moving forward when the engine starts. When an aircraft moves forward, one’s instinct is to step back out of the way, which could lead to a fall.
  
  
• Ensure the area around the propeller is clear of people, animals, and objects. There are many tailless FBO dogs due to rushing or not respecting proper engine start protocol.
  
  
• Confirm that the magnetos are off before handling the propeller. Then, check again.
  
  
• Follow the aircraft’s specific procedure for priming the engine to avoid flooding or improper fuel flow.
  
  
• Ensure the area around the prop is clear. Do this even if you think there’s no one around before throwing the prop blade downward.
  
  
• Use the correct hand-propping technique as described in the POH. If you’ve never done it before, get expert instruction first. For most situations, you will lay your hands flat on the front of the propeller blade while avoiding wrapping your fingers around the trailing edge so that the prop won’t strike your hands if it kicks back.
  
  
• Ensure the throttle is set to idle and the mixture is rich (or as instructed in the POH).
  
  
• Know where to stand and where to go. Position yourself slightly less than one arm’s length from the blade, and step away from the prop arc as you pull it through.
  
  
• Post-flight, ensure that the magnetos are fully grounded and the key is removed from the ignition to help start the next flight safely.

Additional considerations:

• Securing the airplane — give it a nudge to make sure the brakes are applied. Investing in larger chocks and tying down the tail can provide additional security.
  
  
• The ground surface — ensure the area around the aircraft isn't slick (rocks, mud, ice, oil, etc.).
  
  
• Your clothing — ensure you won't trip over loose or long pants or untied shoes. Additionally, be conscious of long sleeves, wedding rings, or anything that could get caught on the prop. Gloves can help here.

Once you’ve gotten expert instruction in hand-propping, then, and only then, should you attempt to hand-prop an airplane. Keep in mind, there’s something even better than learning how to hand-prop an airplane, and it’s much safer. It’s called an electric starter.

Know Before You Go