Why does a pilot say "contact" before the guy spins the propeller for him?

Question

sopwith camel, fokker byplanes

Answer 1

Contact means he's activated the "spark", or engine ignitor.

Answer 2

That means the magneto "CONTACT breaker points" are not grounded.  They're like the points that were in the old car distributors.  So spinning the engine spins the mag and it creates it's own spark.

Magnetos do not need any electrical power to make a spark, they just need to be turned.  So when the pilot "un-grounds" the mags any movement of the engine/prop/magneto might create a spark and the engine will start.  So yelling "contact" means the guy spinning the prop should have a firm grip on the prop and it's ready for starting.

That's why pilots always treat a prop as if it might turn.

Answer 3

Ignition switch is 'on'.

Answer 4

Usually means that the magnetos are on and she's ready to fire!  Brakes Set, Contact and away she goes.

Answer 5

It means the switch has been turned on. That would be the switch that connects an electric current from the engine's magneto to the spark plugs. A magneto was an early version of the engine distributor. Every early engine from a Harley to a tractor had a magneto.

Answer 6

The procedure and commands for hand propping are:

Person out front says, “GAS ON, SWITCH OFF,

THROTTLE CLOSED, BRAKES SET.”

Pilot seat occupant, after making sure the fuel is

ON, mixture is RICH, ignition/magneto switch is

OFF, throttle is CLOSED, and brakes SET, says,

“GAS ON, SWITCH OFF, THROTTLE

CLOSED, BRAKES SET.”

Person out front, after pulling the propeller

through to prime the engine says, “BRAKES

AND CONTACT.”

Pilot seat occupant checks the brakes SET and

turns the ignition switch ON, then says,

“BRAKES AND CONTACT.”

The words CONTACT (mags ON) and SWITCH OFF

(mags OFF) are used because they are significantly

different from each other. Under noisy conditions or

high winds, the words CONTACT and SWITCH OFF

are less likely to be misunderstood than SWITCH ON

and SWITCH OFF.

Never allow a person unfamiliar with the controls to

occupy the pilot’s seat when hand propping.

The procedure should never be attempted alone. (IMHO)

Answer 7

it means the aliens have landed - alien contact..... lol, just kidding

Answer 8

Cherokee was pretty close to right.

The person out front calls out "Mixture rich, throttle closed, brakes set, switch off."

The pilot replies "Mixture rich, throttle closed, brakes set, switch off."

The person out front pulls forward HARD on the propeller to make sure the brakes are holding.  If so, then the pilot operates the primer to inject some fuel into the cylinders, and then the person out front turns the propeller a couple of turns to remove oil from the cylinders.  (Especially important with a radial engine.)

All this done, the person out front calls out "Contact!"  The pilot opens the throttle about 1/4 to 1/2 inch, turns the mag switch to "Both" and calls out "Contact!"

(Some engines start on only one magneto or a special circuit.)

The person out front swings the propeller, using a carefully devised stance and grip to avoid becoming unbalanced in such a way as to fall toward the propeller as it starts.

If all goes well, the engine starts.

As Cherokee mentions, the word "Contact" is used to avoid confusion between "switch off" and "switch on."  I have come close to fistfights with ignorant people who did not want to follow the safe and proper procedure and use the right terms.  I know one line crew member who insists on "all off" and "Git it hot!"

I suppose that's better than some things that he could say.

I fly a little jewel of an airplane with an 85-HP engine that I can usually prop from off to the side with one hand.  Given this, and the fact that the Chief has really reliable brakes, I don't hesitate to prop it myself if it is not convenient to get help (Like at First Flight airport, Kill Devil Hills NC, at dusk.  I go there often.  It is usual for there to be no one in sight at dusk, and overnight parking is prohibited)  So I prop it myself.

Never had any trouble.  But this is the airplane I soloed in, many, many years and hours ago, and I trust it.  I would not try this with a bigger engine or an unfamiliar airplane.

Very little has changed about this since the days of the LeRhone engines.  Be sure you learn the proper stance and grip before you try hand-propping an airplane.  There is more to it than there looks.

Try an internet search on "hand propping airplane."

Then have fun!

Answer 9

Means the juice is turned on and the engine is ready to start they do the same today with under water welding by saying make it hot or contact.

Answer 10

Radial engines are known to have the oil settle into the bottom cylinder when left sitting for a length of time, like over night.  So in the old days, before the first flight of the day, a mechanic would turn the prop by hand to circulate the oil that had pooled in the lower cylinder.  The mechanic would holler to the pilot, "switch off?"  The pilot would reply "switch off" to let the mechanic know it was OK to turn the prop through a couple of times.  Then the mechanic would yell "switch on!" The pilot would yell beck, "switch on", or "contact!" This would let the mechanic know that this time when he pulled the propeller through, the engine would be starting (through magneto grounding etc)

Since neither the Sopwith Camel or the Fokker Tri-plane had brakes, the mechanic would then position himself to pull the chocks that kept the plane from rolling forward until the pilot was ready to go.