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Safety Recommendation Details

Safety Recommendation A-83-019
Details
Synopsis: ON JULY 9, 1982, PAN AMERICAN WORLD AIRWAYS FLIGHT 759 CRASHED AFTER TAKING OFF FROM RUNWAY 10 AT NEW ORLEANS INTERNATIONAL AIRPORT, KENNER, LOUISIANA. WHEN FLIGHT 759 TOOK OFF, THERE WERE ISOLATED HEAVY SHOWERS OVER THE AIRPORT AND TO THE EAST OF THE AIRPORT ALONG THE AIRPLANE'S INTENDED DEPARTURE PATH. LOW LEVEL WIND SHEAR CONDITIONS HAD BEEN DETECTED BY THE AIRPORT'S LOW LEVEL WIND SHEAR ALERT SYSTEM (LLWSAS), AND THE SYSTEM HAD ALARMED SEVERAL TIMES, THE LAST TIME ABOUT 4 MINUTES BEFORE FLIGHT 759'S TAKEOFF. THE SYSTEM WAS NOT ALARMING AT THE TIME THE TAKEOFF CLEARANCE WAS ISSUED; HOWEVER, A WIND SHEAR ADVISORY WAS BROADCAST 2 SECONDS AFTER THE ACCIDENT.
Recommendation: THE NTSB RECOMMENDS THAT THE FEDERAL AVIATION ADMINISTRATION: STUDY THE FEASIBILITY OF ESTABLISHING AIRCRAFT OPERATIONAL LIMITATIONS BASED ON THE DATA AVAILABLE FROM THE LOW LEVEL WIND SHEAR ALERT SYSTEM.
Original recommendation transmittal letter: PDF
Overall Status: Closed - Acceptable Action
Mode: Aviation
Location: Kenner, LA, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: DCA82AA028
Accident Reports: Pan American World Airways, Inc., Clipper 759, Boeing 727-235, N4737
Report #: AAR-83-02
Accident Date: 7/9/1982
Issue Date: 3/25/1983
Date Closed: 6/18/1990
Addressee(s) and Addressee Status: FAA (Closed - Acceptable Action)
Keyword(s): Low Level Windshear, Weather, Wind

Safety Recommendation History
From: NTSB
To: FAA
Date: 6/18/1990
Response:

From: FAA
To: NTSB
Date: 10/27/1988
Response:

From: FAA
To: NTSB
Date: 5/26/1988
Response: A redesigned and improved LLWAS was operationally tested at Denver Stapleton Airport in 1987. The results of this test were positive, and the modified LLWAS will be commissioned this year. This redesigned system provides runway-oriented wind information which is transmitted to pilots as a gain or loss of speed. The effort described in the response to Safety Recommendation A-83-18 also applies to this safety recommendation. The feasibility of establishing aircraft operational limitations is being studied by a multidisciplinary team which is provided oversight by a steering group composed of representatives of the aircraft manufacturers, aircraft operators, pilot organizations, NTSB technical staff, NASA, FAA, NCAR, and Lincoln Lab. I am confident that this will provide us with the right answers in the shortest possible time. I believe that the ongoing actions fully meet the intent of this safety recommendation as issued to the FAA, and I urge the Safety Board to classify this safety recommendation as "closed."

From: FAA
To: NTSB
Date: 9/16/1986
Response:

From: NTSB
To: FAA
Date: 9/16/1986
Response: In the course of the Safety Board's investigation of an accident involving Delta Air Lines flight 191 at Dallas/Fort Worth International Airport, Texas, on August 2, 1985, the Safety Board has performed a detailed review of all Safety Recommendations, currently classified as open, issued to the FAA on the subject of windshear. Also addressed in this review were three Safety Recommendations that discussed the timely detection of severe weather, though not specifically related to windshear or microbursts. The Safety Board's review included past FAA responses, evaluation of the FAA's letters of September 24, 1985, and May 5, 1986, and our analysis of the FAA's Integrated Wind Shear Program Plan. A more descriptive review of the FAA's responses to these Safety Recommendations and of the program plan is contained in appendix H of the Safety Board's report of the Delta flight 191 accident. The open Safety Recommendations reviewed by the Safety Board are as follows: A-74-13 A-76-34 A-77-63 A-80-118 A-83-15 A-83-18 A-83-19 A-83-20 A-83-21 A-83-22 A-83-23 A-83-24 A-83-25 A-85-26 A-85-27 The Safety Board has carefully reviewed the Integrated Wind Shear Program Plan and the two letters from the FAA mentioned above and finds that the actions concurrently being taken and planned by the FAA will comply with the intent of all of the above Safety Recommendations when implemented. Therefore, all of the above-listed Safety Recommendations have been classified as "Open--Acceptable Action" pending completion of the FAA's planned actions. The Safety Board appreciates the FAA's actions to improve windshear detection and avoidance, and in the dissemination of information on windshear.

From: NTSB
To: FAA
Date: 10/1/1985
Response: We note that at the present time meaningful data are not available either through the LLWAS or the Doppler radar program to establish aircraft operational limitations. We are hopeful that when the LLWAS is improved with more sensors, and the Doppler radar program is developed further, the FAA will be in a better position to address aircraft operating limitations. We request to be informed of the progress of this recommendation which is classified "Open--Acceptable Action."

From: FAA
To: NTSB
Date: 4/2/1985
Response: FAA LTR: THE LLWAS IS BEING REDESIGNED TO INCLUDE MORE SENSORS, AS WELL AS DIFFERENT SOFTWARE, WHICH WILL ANALYZE THE WIND CONDITIONS AT MULTIPLE LOCATIONS ABOUT THE RUNWAY. THE QUALITY OF THE NEW WIND DATA MAY ALLOW OPERATIONAL LIMITATIONS TO BE BASED ON THAT WIND INFORMATION; HOWEVER, WE DO NOT YET HAVE SUFFICIENT DATA FOR A MEANINGFUL EXAMINATION OF THAT CONCEPT AT THE PRESENT TIME. IN ADDITION, THE DOPPLER RADAR PROGRAM MENTIONED IN OUR RESPONSE TO SAFETY REOMMENDATION A-83-18 WILL PROVIDE DATA POTENTIALLY USEABLE FOR ESTABLISHMENT OF OPERATIONAL LIMITATIONS FOR VARIOUS AIRCRAFT. AGAIN, BOTH OF THE PROGRAMS ARE IN EARLY STAGES, AND SUFFICIENT DATA DOES NOT YET EXIST TO SUPPORT SUCH LIMITATIONS.

From: NTSB
To: FAA
Date: 5/29/1984
Response: We acknowledge the limitations of the LLWAS, that it provides only the wind data which are measured at the ground and within the immediate vicinity of the runway, and that the data are not adequate to quantify the intensity of wind shear which could be present on an airplane's approach or departure flightpath. Nonetheless, as you have indicated, it is the best system available today and we believe that it should be used to maximum advantage. The use of LLWAS for operational decisions could be optimized if a pilot were able to compare the longitudinal wind gradient which is measured by LLWAS to the hazard it presents to his particular airplane. Within this context we believe that it is possible currently to define operational limitations for various airplanes in terms of the longitudinal wind gradient along the runway and that the establishment of such limitations should be kept in mind as changes to LLWAS software and other system enhancements are studied in the evaluation to which you referred in your response to Safety Recommendation A-83-20. Data Source: NTSB Recommendations to FAA and FAA Responses Accordingly we urge the FAA to reconsider this recommendation in a broader context than the presently installed sensors and LLWAS software. Pending further response, Safety Recommendation A-83-19 will be classified as "Open--Unacceptable Action."

From: FAA
To: NTSB
Date: 7/21/1983
Response: FAA LETTER: CURRENT SENSORS DO NOT PROVIDE ACCURATE MEASUREMENT OF SHEAR VELOCITIES AS THEY ARE ENCOUNTERED IN THE APPROACH AND DEPARTURE PATH BY PILOTS. FUTURE SYSTEMS, SUCH AS NEXRAD (NEXT GENERATION RADAR) WILL PROVIDE IMPROVED INFORMATION ON HORIZONTAL SHEAR STRENGTH BUT NOT ON VERTICAL SHEARS. THE FAA BELIEVES THAT THE LLWSAS IS REPRESENTATIVE OF THE BEST SYSTEM AVAILABLE AT PRESENT WITH TODAY'S TECHNOLOGY AND IS USED BY PILOTS TO HELP MAKE OPERATIONAL DECISIONS REGADING SEVERE CONVECTIVE WEATHER. IT MUST BE UNDERSTOOD, THAT THE INFORMATON DERIVED FROM THE LLWSAS IS NOT NECESSARILY ADEQUATE TO QUANTIFY THE INTENSITY OF THE WEATHER HAZARD AND MUST BE COMBINED WITH OTHER INFORMATION (I.E., PILOT REPORTS, VISUAL SIGNS, GROUND AND AIRBORNE RADAR, AIRCRAFT PERFORMANCE CHARACTERISTICS) BEFORE AN OPERATIONAL DECISION IS MADE. THE LLWSAS IS A USABLE TOOL BUT NOT FOR THE PURPOSE OF ESTABLISHING OPERATIONAL AIRCRAFT LIMITATIONS. THE NATIONAL ACADEMY OF SCIENCE STUDY ON WIND SHEAR IS ADDRESSING THE IMPACT OF WIND SHEAR ON AIRCRAFT PERFORMANCE AND IS EXPECTED TO RESULT IN RECOMMENDATIONS ON PILOT TRAINING FOR OPERATIONS IN WIND SHEAR CONDITIONS.