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ON JANUARY 23, 1982, WORLD AIRWAYS, INC., FLIGHT 30H, A MCDONNELL DOUGLAS DC-10-30, WAS A REGULARLY SCHEDULED PASSENGER FLIGHT FROM OAKLAND, CALIFORNIA, TO BOSTON, MASSACHUSETTS, WITH AN EN ROUTE STOP AT NEWARK, NEW JERSEY. FOLLOWING A NONPRECISION INSTRUMENT APPROACH TO RUNWAY 15R AT BOSTON-LOGAN INTERNATIONAL AIRPORT, THE AIRPLANE TOUCHED DOWN ABOUT 2,500 FEET BEYOND THE DISPLACED THRESHOLD OF THE RUNWAY, LEAVING 6,691 FEET REMAINING ON WHICH TO STOP. ABOUT 1936:40, THE AIRPLANE VEERED TO AVOID THE APPROACH LIGHT PIER AT THE DEPARTURE END OF THE RUNWAY AND SLID INTO THE SHALLOW WATER OF BOSTON HARBOR. THE NOSE SECTION SEPARATED FROM THE FORWARD FUSELAGE AFTER THE AIRPLANE DROPPED ONTO THE SHORE EMBANKMENT. OF THE 212 PERSONS ON BOARD, 2 ARE MISSING AND PRESUMED DEAD. THE OTHERS EVACUATED THE AIRPLANE SAFELY, BUT WITH SOME INJURIES. THE REPORTED WEATHER WAS A MEASURED 800-FOOT OVERCAST, 2 1/2 MILE VISIBILITY, LIGHT RAIN AND FOG, TEMPERATURE 35 DEGREES, AND WIND 165 DEGREES AT 3 KNS. THE WET RUNWAY WAS COVERED WITH HARD-PACKED SNOW AND A COATING OF RAIN AND/OR GLAZED ICE.
THE NTSB RECOMMENDS THAT THE FEDERAL AVIATION ADMINISTRATION: AMEND 14 CFR25.735 TO REQUIRE THAT MANUFACTURERS OF TRANSPORT CATEGORY AIRPLANES DETERMINE AND DEMONSTRATE THE EFFICIENCY OF BRAKE CONTROL SYSTEMS ON SURFACES WITH LOW FRICTION COEFFICIENTS REPRESENTATIVE OF WET AND ICY RUNWAYS BY USING SIMULATION TECHNIQUES INCORPORATING DYNAMOMETER TESTS AND ACTUAL BRAKE SYSTEM COMPONENTS, OR BY ACTUAL FLIGHT TEST. (Supersedes Safety Recommendations A-74-119 through -121 and A-76-136 and -137)
Original recommendation transmittal letter:
Closed - Reconsidered
BOSTON, MA, United States
World Airways, Inc., Flight 30H, McDonnell Douglas DC-10-30CF, N113WA
Addressee(s) and Addressee Status:
FAA (Closed - Reconsidered)
Safety Recommendation History
In correspondence dated May 20, 1987, the Safety Board acknowledged the difficulty of accurately measuring antiskid brake system efficiencies on surfaces with low friction coefficients using presently available testing and simulation techniques. However, the National Aeronautics and Space Administration, Langley Research Center is using their Aircraft Landing Dynamics Facility to perform tests on the space shuttle brake systems under different surface friction conditions. The Safety Board believes that such technology could be transferable to the new aircraft certification process and that FAA should conduct further research in this area. However, since research is beyond the scope of the recommendation, A-82-166 is being reclassified "Closed--Reconsidered."
The Safety Board is aware of the efforts made by the National Aeronautics and Space Administration and anti-skid manufacturers to determine and enhance the efficiency of anti-skid systems on contaminated runway surfaces. The Safety Board's original concern, still present today, is that anti-skid systems may be designed to provide their optimum efficiency on dry runway/pavement surfaces since transport category airplane landing and takeoff data are calculated from dry runway performance. We are concerned that there are no objective criteria for establishing that the anti-skid system provides the best compromise in performance on dry and slippery runway surfaces. We are sensitive to the difficulty of adequately measuring brake system efficiencies. For instance, testing in a controlled environment using single wheel track tests cannot be relied upon to estimate actual airplane runway performance. As a result, the Safety Board realizes that more work and testing must be accomplished before anti-skid systems can be compared for efficiency on slippery surfaces. In the interim, modern anti-skid systems have demonstrated good performance under most circumstances. Although the Safety Board feels there is room for improvement, we are aware that defining true anti-skid efficiency for a variety of aircraft, speeds, and runway conditions is difficult at best. The Safety Board nevertheless encourages the FAA to strive for improvements in this area. In lieu of determining and demonstrating anti-skid efficiencies for transport category airplanes on surfaces with low coefficients of friction, the Safety Board will await the release of Advisory Circular (AC) 91-6A. Pending the release of the AC, this recommendation is classified in an "Open--Acceptable Alternate Action" status.
BECAUSE OF THIS VARIABILITY IN METHODS OF MEASURING AND COM PARING BRAKE EFFICIENCY, AND LACK OF CONFIDENCE IN SIMULA TION DATA FOR USE IN PREDICTING BRAKING PERFORMANCE, I DO NOT AGREE WITH THE BOARD'S RECOMMENDATION. THE FAA WILL, HOWEVER, ISSUE AN ADVISORY CIRCULAR (AC) 91-5A, PERFORMANCE INFORMATION FOR OPERATION WITH WATER, SLUSH, SNOW, OR ICE ON THE RUNWAY. THIS AC WILL PROVIDE THE TAKEOFF AND LANDING PERFORMANCE OF TURBINE POWERED AIRCRAFT ON WET RUNWAYS OR RUNWAYS CONTAMINATED BY STANDING WATER, SLUSH, SNOW, OR ICE AND PROVIDE ADJUSTMENTS TO BE APPLIED UNDER THESE CONDI TIONS. ADOPTION OF THIS AC, TOGETHER WITH THE RULEMAKING DISCUSSED IN MY RESPONSE A-82-163, WILL PROVIDE FOR INCREASED SAFETY DURING OPERATIONS ON SLIPPERY RUNWAYS.
The Safety Board is concerned that current 14 CFR Part 25 requirements are not specific with regard to antiskid system performance on surfaces with different faction characteristics. The FAA's "Engineering Flight Test Guide for Transport Category Airplanes," FAA Order 8110-8. has some definitive guidance for compliance with 14 CFR 25.735(e) stating that the antiskid equipment should ensure satisfactory operation on slippery runways as well as on dry, hard surfaced runways without additional antiskid adjustments. We understand that the functioning of antiskid equipment is examined during landings on wet surfaces during the airplane's certification program. However, the determination of satisfactory operation appears to be subjective, and the wet runway surfaces are not representative of low coefficient-of-friction surfaces covered with snow or ice. Although the Safety Board acknowledges that the determination of antiskid system performance on surfaces having a wide range of friction coefficients, through simulation or flight test, presents a difficult problem, it believes that such data are essential to the goal of presenting comprehensive stopping data to pilots. It therefore believes that FAA should continue to examine, perhaps through joint research with the National Aeronautics and Space Administration (NASA) and industry, methods by which antiskid brake system performance can be defined and demonstrated. We urge you to consider such an effort and respond to us regarding any FAA actions to resolve this issue. The Safety Board will hold Safety Recommendation A-82-166 in an "Open--Unacceptable Action" status pending your consideration of our comment.
FAA LETTER: MANUFACTURERS UTILIZE WET AND DRY RUNWAY TESTS IN TUNING THE ANTISKID TO OPTIMIZE OVERALL BRAKING PERFORMANCE. IN ADDITION, CURRENTLY CERTIFICATED LARGE TRANSPORT CATEGORY AIRCRAFT HAVE SATISFACTORILY DEMONSTRATED DURING CERTIFICATION TESTING, AS REQUIRED BY 14 CFR 25.1309(A), THAT THE ANTISKID SYSTEM FUNCTIONS AS INTENDED ON WET AND DRY RUNWAYS. BECAUSE OF THE VARIABILITY IN METHODS OF MEASURING AND COMPARING BRAKING EFFICIENCY, AND BECAUSE OF OUR LACK OF CONFIDENCE IN SIMULATION FOR USE IN PREDICTING BRAKE PERFORMANCE, WE DO NOT AGREE WITH THE BOARD'S RECOMMENDATION.
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