The Why and How of Runway Friction Testing

by

Delia HarversonFindlay Irvine Ltd.

Midlothian, Scotland

and

Thomas J. YagerNASA Langley Research Center

Hampton, VA, USA

Part 1: A Brief History

What were the first Continuous reading Friction Measuring Equipments

[CFMEs]

??When were they introduced

??

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The first CFME was the Skiddometer

designed in Sweden in the late 1950s

the second CFME

designed by the UK Ministry of

Defence in the early 1960s

was the

1962: a Canberra lands on a winter contaminated runway ...

Why were these early CFMEs Why were these early CFMEs developed?developed?

… and comes safely to a stop

The first CFMEs were developed The first CFMEs were developed mainly for testing in winter mainly for testing in winter

conditionsconditions

After the Skiddometer and the MuMeter came the Saab Friction Tester

which was also originally designed to measure in winter conditions

Later CFMEs were designed as much for maintenance testing as for operational testing

Is it as important to measure runway friction in summer as in winter??

YES!YES!

In rain, a runway with poor texture and rubber deposits can be just as slippery as a

runway contaminated with ice and snow

questionquestionquestionquestion

An accident waiting to happen …An accident waiting to happen …

Are there more overrun accidents on wet runways or on runways contaminated with

ice and snow?

There are substantially more overrun accidents on wet runways

Most of these accidents Most of these accidents need never have need never have

happenedhappened

another questionanother questionanother questionanother question

Nothing will guarantee that an overrun accident won’t happen at your airport …

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… but regular use of an approved, well maintained CFME will make it less likely

Operational testing is carried out in natural conditions, in winter, in order to make immediate operational decisions.

Maintenance testing is carried out in carefully controlled conditions, which include an exact amount of water put down in front of the measuring wheel, in order to make engineering decisions.

operational & maintenanceoperational & maintenancetestingtesting

operational & maintenanceoperational & maintenancetestingtesting

Should engineering decisions ever be made on the basis of operational testing?

No!No!Natural conditions are much too variable to provide a proper basis for engineering

decisions

operational & maintenanceoperational & maintenancetestingtesting

operational & maintenanceoperational & maintenancetestingtesting

How do we ensure that maintenance friction testing is consistent …

… that the same results are obtained in Lima as in London Heathrow?

… in Santa Cruz as in Singapore?

runway friction testingrunway friction testingrunway friction testingrunway friction testing

For this, the international community depends on

ICAOICAO

runway friction testingrunway friction testingrunway friction testingrunway friction testing

Forget it!

runway friction testingrunway friction testingrunway friction testingrunway friction testing

Before we get onto ICAO’s role, two quick words about the lunch-box test …