Research Aims To Prevent Accidents
On Hazardous Runways
makes a test run on a snowy runway in Michigan.
Runway water, ice or snow was a factor in more than 100 airplane
accidents between 1958 and 1993. Most of those accidents involved
supports a national goal to reduce the fatal aircraft accident rate
by 80 percent in 10 years and by 90 percent in 25 years.
To help accomplish this ambitious agenda, NASA Langley Research
Center has partnered with Transport Canada and the Federal Aviation
Administration (FAA) in an on-going,
5-year winter runway friction measurement program.
The research effort uses instrumented aircraft,
friction-measuring ground vehicles and test personnel from around
Results will benefit aircraft, airports
The major objectives of the Joint Winter Runway Friction
- Coordinating different ground vehicle friction measurements to
develop a consistent friction scale for similar potentially
hazardous runway conditions.
- Establishing reliable correlation between ground vehicle
friction measurements and aircraft braking performance.
Accomplishing these objectives would not only give airport
operators a better way to evaluate runway friction and maintain
acceptable operating conditions, but would also contribute to
reducing traction-related aircraft accidents.
Testing began in 1996
Since testing started in January 1996, 5 instrumented aircraft
and 13 ground test vehicles have been evaluated at sites in Canada,
the United States, and Norway. The test aircraft have included the
Canadian National Research Council's Falcon 20, the FAA's B727, a
deHavilland Dash 8, and NASA's B737 and B757. The
friction-measuring ground devices have come from a number of
international partners. Transport Canada's surface friction tester
and electronic recording decelerometer, the Scottish GripTester,
the French IMAG, and Norway's
and airport surface friction tester have all contributed data. So
have the FAA's runway friction tester and BV-11 trailer, the
American Society for Testing and Materials (ASTM) E-274
skid trailer, and NASA's instrumented tire-test vehicle and
Data collected from 1996--1999 includes nearly 400 instrumented
aircraft test runs and more than 8000 ground vehicle runs. Tests
were performed on a variety of runway conditions:
- Bare and dry
- Rain and artificially wet
- Artificially flooded
- Loose and compacted snow
- Smooth and rough ice
- Sanded and chemically treated ice
Researchers also took manual measurements to monitor conditions
before and after a test run series. They recorded ambient
temperature; temperatures of pavement surface and snow, slush, or
ice; depth of cover material (water, snow, slush, ice); and in the
case of snow or slush, density of cover material.
Researchers take measurements before aircraft and ground vehicles
conduct their runway tests.
From this substantial friction database, engineers have
developed an international runway friction index (IRFI) to
standardize friction reporting from different devices and to
minimize pilot difficulties in making critical takeoff and landing
decisions. An IRFI methodology standard that defines procedure and
accuracy requirements is under review for approval by an ASTM
More tests planned
Future test plans include:
- Standard-equipped wide-body aircraft tests at a European
- Falcon 20, Dash 8, and B757 aircraft tests at North Bay,
Ontario, and Sawyer Airport, Gwinn, Michigan.
- Ground vehicle tests during annual NASA Wallops Flight Facility
workshop in Virginia and at a special test track in Oslo,
The overall results from this program will increase aircraft
safety and the capacity of airports where winter conditions are
severe. Some of the results and test procedures may also apply to
For more information, visit our Web site: http://sdb-www.larc.nasa.gov/SDB/