I have a question regarding runway surfaces that I have not been able to find an answer to over the Internet!!
Quite often, I have noticed from inside the plane (just before taking off) that the runway sections near the threshold markings are ribbed!! I commonly assumed that they were there to provide traction/better grip during the take-off??
But since the power plants of modern jets aren’t connected to the wheels, there wouldn’t be any wheel spin or slippage (correct me if I am wrong) while taking off would there?
Could you please explain what these ribbed sections do and are they related to traction at all?
Thank you for your time
Charlie
Hi Charlie,
The ‘ribbed’ runway surfaces you are referring to are in fact known as ‘grooved’ runway surfaces. The main function is to prevent hydroplaning (skidding on wet runway conditions). The grooves allow water film to flow off the runway surface easily following a heavy rain and the peaks between the grooves will be in contact with the aircraft tyres. Additionally, these grooves maximise friction for wheel braking.
As you are aware, wet runways affect aircraft performance. Heavy rain water can contaminate the runway surface as well as causing dangerous landing conditions. So it can have serious adverse effects on ground controllability as well as braking efficiency of the plane in a heavy downpour.
The grooves are meant mainly to facilitate the landing process rather than for the take off phase. So even though the wheels are not connected to the engine like your car, skidding can occur during the braking stage on landing. All planes have very good anti-skid braking system unless they fails.
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