c PB86-910406 / L NATIONAL * TRANSPORTATION SAFETY BOARD WASHINfSTON, D.C. 20594 AIRCRAFT ACCIDENT REPORT DELTA AIR LINES, INC., LOCKHEED L-101 l-385-1, N726DA DALLAS/FORT WORTH - INTERNATIONAL AIRPORT, TEXAS AUGUST 2,1985 NTSBIAAR-86/05 UNITED STATES. .-. GOVERNMENT REPRODUCE0 BY - - - U.S. DEPARTMENT DF COMMERCE NATIONAL TECHNICAL INFORMATION SERVICE SPRINC3FIELD. VA. 22161 -. -_ .__ TECHNICAL- -----_--- -- -.-. REPORT ---- ----.. DOCUMENTATTfIN --. --.. PAGF. ..-- I Report No. Z.Government Accession No. 3.Recipient’s Catalog No. ‘NTSB/AAR-86IOj PB86-910406 4 Title and Subti tie Aircraft .Accldent K t--uelta 5.Report Date ‘Air Lines, Inc., Lockheed L-loll-385-1, N’7‘ii%fi, August 15, 1986 Dallas/Fort i\;ortll International Airport, Texas, 6.Performing Organization Auplst 2, 1985 Code 7. Author(s) 8.Performing Organization Report No. 9. Performing Organization Name and Address 10.Woqr3k2i;i t No. National Transportation Safety ijoard d Rurcau of Accident Investigntmn ll.Contract or Grant No. Washington, D.C. 20594 13.Type of Report and Period Covered 12.Sponsoring Agency Name and Address Aircraft Accident Beport August 2, 1985 NATIONAL TRANSPORTATION SAFETY BOARD Washington, D. C. 20594 14.Sponsoring Agency Code ls.Supplementary Notes 16.Abstract On August 2, 1’385, at 1805:52 central daylight -time, Delta Air Lines flight 1 Y 1, a Lockheed L-1011-385-1. UTZliDA, crashed while,approaching to land on runway 1SL at tile Dallas Fort CVorth International Airport, Texas. (While passing through the rain shaft beneath a thuflderstor:n, flight lY1 entered a inicroburst which the pilot was unabie to traverse successfuliy. The airplane struck the ground about 6,300 feet north of the approach end of runway 1’7L, hit a car on a highway north of the runway killing the driver, struck two water tanks. on tile airport, and broke apart. Except for a section of the airplane containing the aft fuselage and empennage, the remainder of the airplane disin egrated during the impact sequence, and a severe fire erupted during the impact sequence. Of the 163 persons aboard. 134 passengers and crewmembers were killed; 26 passengers and 3 cabin attendants survived. The National Transportation Safety Board determines that the probable causes of the accident -were the flightcrew’s decision to initiate and continue the approach into a cumulonimbus cloud which they observed to contain visible lightning; the lack of specific guidelines, procedures, and training for avoiding and escaping from low-altitude wind shear; and the lack of definitive, real-time wind shear hazard information. This resulted in the aircraft’s encounter at low altitude with a microburst-induced, severe wind shear from a rapidly developing thunderstorm located on the final approach course. ’ 7* Key ‘Ords <nstrument approach; fhunderst This document is available tiicroburst;%ind shear; -Doppler radar; from the National Technical heather; WWF%; In- tion; Information Service, cures Springfield, Virginia, 22161 19Securi ty Classification 20.Security Classification 2l.No. of Pages 22.Price (of this report) (of this page) 166 UNCLASSIFIED UNCLASSIFIED. NTSB FO~III 1765.2 (Rev. g/74) I CONTENTS SYNOPSIS. , . 1 1. FACTUAL INFORMATION. .................. 1 1.1 -History of the Flight ..................... 1 1.2 Injuries to Persons ...................... f 1.3 Damage to Airplane ...................... 1.4 Other Damage ........................ i 1.5 Personnel Information ..................... 1.6 Airplane Information ..................... 7 1.7 .. Meteorological Information. .................. 8 1.7.1 WeatherRadarData. ..................... 9 1.7.2 The Fort Worth NWS Forecast Office ............... 11 1.7.3 The Fort Worth ARTCC’s Center Weather Service Unit. ...... 13 1.7.4 The Contract Weather Observer. ................ 15 1.7.5 Delta Air Lines Meteorological and Dispatch Departments ..... 17 1.7.6 Witness Statements ...................... 17 1.8 Navigational Aids ............. ; ......... 23 1.9 Communications ....................... 23 1.10 Aerodrome Information .................... 23 1.10.1 Low Level Wind Shear Alert System ............... 23 1.11 Flight Recorders ....................... 24 1.12 Wreckage and Impact Information ................ 25 1.13 Medical and Pathological Information .............. 27 1.14 Fire. ............................. 27 1.15 Survival Aspects ....................... 28 1.15.1 Emergency Response ..................... 30 1.16 Tests and Research ...................... 31 i.16.1 Wind Shear Research ..... ................ 31 1.16.2 Wind Field Analysis ...................... 34 1.16.3 Airplane Performance ..................... 38 1.16.4 -Flight Director System Study .................. 40 1.16.5 Weather Analysis ....................... 41 1.16.6 Flight Attendant’s Jumpseat Restraint Systems .......... 41 1.17 Other Information. ...................... 42 1.17.1 Air Traffic Control Procedures ................. 42 1.17.2 Air Traffic Control Procedures at the DFW Airport Traffic Control Tower. ....................... 43 1.17.3 Delta Air Lines Flight Operation Procedures and Training ..... 50 1.17.4 Low Level Wind Shear Detection Systems--Air and Ground ..... 55 2. ANALYSIS, ......................... 58 2.1 General ........................... 58 2.2 Meteorological Factors .................... 58 2.3 Air Traffic Control ...................... 62 2.4 Operational Factors ...................... 67 2.5 Occupant Survival. ...................... 7 5 3. CONCLUSIONS. ....................... 78 3.1 Findings. .......................... 78 3.2 ProbabIe Cause. ....................... 80 4. RECOMMENDATIONS. , . 80 4.1 Recommendations Addressing Low-Altitude Wind Shear and Weather. 88: 4.2 Other Recommendations . Preceding page blank iii 5. APPENDIXES . , . , . , , . , . , . 91 Appendix A--Investigation and Public Hearing . 91 Appendix B--Personnel Information . 92 Appendix C--Airplane Information . 95 Appendix D--Dallas Fort Worth International Airport Diagram . 96 Appendix E--Runway 17L Instrument Landing System (IL8 Approach Chart . 97 Appendix F--Cockpit Voice Recorder Transcript . 98 Appendix G--Federal Aviation Administration Advisory Circular OO-SOA, January 23, 1979 . 137 Appendix H--Previous Safety Recommendations on Wind Shear and Detection of Severe Weather . , . 154 Appendix I--DFDR/CVR Integrated Plot . * 164 iv NATIONAL TRANSPORTATION SAFETY BOARD WASHINGTON, D.C. AIRCRAFT ACCIDENT REPORT Adopted: August 15,1986 DELTA AIR LINES, INC. LOCKHEED L-1011-385-1, N726DA, DALLAS/FORT WORTH INTERNATIONAL AIRPORT, TEXAS AUGUST 2, 1985 SYNOPSIS On August 2, 1985, at 1805:52 central daylight time, Delta Air Lines flight 191, a Lockheed L-1011-385-1, N726DA, crashed while approaching to land on runway 17L at the Dallas/Fort Worth International Airport, Texas. While passing through the rain shaft beneath a thunderstorm, flight 191 entered a microburst which the pilot was unable to traverse successfully. The airplane struck the ground about 6,300 feet north of the approach end of runway 17L, hit a car on a highway north of the runway killing the driver, struck two water tanks on the airport, and broke apart. Except for a section of the airplane containing the aft fuselage and empennage, the remainder of the airplane disintegrated during the impact sequence, and a severe fire erupted during the impact sequence. Of the 163 persons aboard, 134 passengers and crewmembers were killed; 26 passengers and 3 cabin attendants survived. The National Transportation Safety Board determines that the probable causes of the accident were the flightcrew’s decision to initiate and continue the approach into a cumulonimbus cloud which they observed to contain visible lightning; the lack of specific guidelines, procedures, and training for avoiding and escaping from low-altitude windshear; and the lack of definitive, real-time windshear hazard information. This resulted in the aircraft’s encounter at low altitude with a microburst-induced, severe windshear from a rapidly developing thunderstorm located on the final approach course. - 1. FACTUAL INFORMATION 1.1 History of the might On August 2, 1985, Delta Air Lines (Delta) flight 191 was a regularly scheduled passenger flight between Fort Lauderdale, Florida, and Los Angeles, California, with an en route stop at the Dallas/Fort Worth International Airport, Texas (DFW Airport). Flight 191, a Lockheed L-1011-385-1 airplane, departed Fort Lauderdale on an instrument flight rules UFR) flight plan with 152 passengers and a crew of 11 on board at 1510 eastern daylight time. The DFW Airport terminal weather forecast contained in the flightcrew’s dispatch document package stated, in part, that there was a possibility of widely scattered rain showers and thunderstorms, becoming isolated after 2000 central daylight time. &/ The dispatch package also contained company Metro Alert Yo. T87, valid to 2100, wMch stated that “an area of isolated thunderstorms is expected over _ Oklahoma and northern and northeastern Texas. a few isolated tops to above i/mimes herein are central daylight based on the 24-hour clock. -2- FL 450.” 21 The flightcrew had reviewed this data before takeoff and did not call Delta’s weather facility in Atlanta, Georgia, for any additional weather information. The flight was uneventful until passing New Orleans, Louisiana. A line of weather along the Texas-Louisiana gulf coast had intensified. The flightcrew elected to change their route of flight to the more northerly Blue Ridge arrival route to avoid the developing weather to the south. This change