TP 13579 PROCEEDINGS of the 2nd International Meeting ... - UQAC

IMAPCR ’99
• for operation of aircraft, the acceptable uncertainties related to measuring the variables
for calculating different tribosystems are not described.
• the ICAO documentation indicates an accuracy for reporting of friction characteristics
(wet friction, compacted snow, and ice) that cannot be met because of uncertainties in
the measurement methods used.
• the language used in ICAO documents dealing with snow, slush, ice, and water on the
movement area is not consistent and does not reflect all types of operational surfaces.
129. To ensure effective implementation of the safety-related Standards and Recommended
Practices, Mr. Norheim recommended that ICAO address the discrepancies outlined and
that the current knowledge of different scientific disciplines be applied in the updating
process.
130. The moderator added that the concern expressed in Mr. Norheim’s presentation was shared
by those present and that ICAO needs to address and clarify the documentation.
Statistical Methodology for International Runway Friction Index (IRFI)
131. James C. Wambold, CDRM, Inc., State University, Pennsylvania, spoke of two objectives:
• to compile a database containing all available data from winter and summer conditions
using different measuring devices, tires, and aircraft tire braking performances;
• to correlate the data to determine a harmonized runway friction index: the International
Runway Friction Index (IRFI).
132. Mr. Wambold introduced the concept of a reference device – an arbitrary device that makes
use of virtual reference, i.e., using an average of all participating devices (used in the IFI).
133. He then presented a statistical model:
IRFI = a + b DEV
where a & b were calibrated by regressing REF DEV = a + b DEV
134. By regressing and calibrating the formula, an average R 2 of 0.928 was achieved.
135. Mr. Wambold concluded that:
• a reference device for the IRFI is needed;
• the Statistical IRFI has been developed;
• an ASTM Standard has been drafted.
18