REPORT Ireland

REPORT Following the study performed at the request of The Minister in charge of the Department for Public Enterprise on the AER LINGUS VISCOUNT EI-AOM accident occurred on March 24th, 1968 near TUSKAR ROCK Ireland VOLUME I : STUDY REPORT November 27, 2001 Yves LEMERCIER -Manuel PECH -Colin TORKINGTON Photograph by courtesy of Paul Duffy 1 VOLUME I CONTENTS LIST EXECUTIVE SUMMARY REPORT Page 9 STUDY REPORT 11 1. INTRODUCTION 1.1. HISTORICAL RECALL 12 1.2 THE INTERNATIONAL TEAM 13 1.3 THE TASK (s) 13 2. METHODOLOGY 15 2.1 1970 REPORT METHODOLOGY 15 2.1.1 Methodology Applied 15 2.1.2 Assessment 15 2.2 2000 REVIEW METHODOLOGY 16 2.2.1 Methodology of the Review 16 2.2.2 Assessment 17 2.3 METHODOLOGY OF THE PRESENT STUDY 18 2.3.1 “Similarities” Study 18 2.3.2 Technical Study 18 2.3.3. Operational Study 19 3. “SIMILARITIES” STUDY 20 3.1 AVAILABLE DATA 21 3.1.1 Viscount Occurrences (1976-1995) 21 3.1.2 ICAO Data 21 3.1.3 Accident Reports Examination 21 3.2 “SIMILARITIES” STUDY METHODOLOGY 22 3.3 IDENTIFICATION OF SIMILARITIES 25 3.3.1 With Accidents caused by ICING 25 3.3.1.1 Description of the Accidents :N 7462, SE FO8, G-OHOT 25 3.3.1.2 Comparison with EI AOM Accident 29 3.3.1.3 Conclusions 29 3.3.2 With Accidents caused by a STALL 3.3.2.1 Description of EI AOF Accident 30 3.3.2.2 Comparison with EI AOM Accident 30 3.3.2.3 Conclusion 31 3.3.3 With Accidents caused by a BIRD-STRIKE 31 3.3.3.1 Description of N 7430 Accident 33 3.3.3.2 Comparison with EI AOM Accident 33 3.3.3.3 Conclusion 34 2 3.3.4 With Accidents caused by a STRUCTURAL FAILURE 35 3.3.4.1 Description of the Accidents : SP-LVA and HK 1058 35 3.3.4.2 Comparison with EI AOM Accident 37 3.3.4.3 Conclusion 37 3.3.5 With Accidents caused by an ELEVATOR TAB CIRCUIT 37 FAILURE 3.3.5.1 Description of PK-IVS Accident 38 3.3.5.2 Comparison with EI AOM Accident 40 3.3.5.3 Conclusion 40 3.3.6 With Accident caused by a REAR PRESSURE BULKHEAD 41 FAILURE 3.3.6.1 Description of G-APEC Accident 41 3.3.6.2 Comparison with EI AOM Accident 43 3.3.6.3 Conclusion 43 3.3.7 With Accident caused by an ALTERNATIVE POWER 44 SUPPLY DISRUPTION 3.3.7.1 Description of G-ATFN Accident 43 3.3.7.2 Comparison with EI AOM Accident 46 3.3.7.3 Conclusion 46 3.3.8 With Accident caused by a PCU contamination 47 3.3.8.1 Description of CF-THT Accident 47 3.3.8.2 Comparison with EI AOM Accident 47 3.3.8.3 Conclusion 47 3.3.9 With Accident caused by UNCOMMANDED GROUND FINE 48 PITCH IN FLIGHT 3.3.9.1 Description of N 7404 Accident 48 3.3.9.2 Comparison with EI AOM Accident 48 3.3.9.3 Conclusion 48 3.3.10 With Accident caused by a DOOR STRIKE 49 3.3.10.1 Description of G-ASPL Accident 49 3.3.10.2 Comparison with EI AOM Accident 50 3.3.10.3 Conclusion 50 3.3.11 With Accident caused by a DOOR FLAPPING IN FLIGHT 51 3.3.11.1 Description of FNF SO30P Accident 51 3.3.11.2 Comparison with EI AOM Accident 52 3.3.11.3 Conclusion 52 3.3.12 With an UNEXPLAINED LOSS OF CONTROL 53 3.3.12.1 Description of VT-DIO Accident 53 3.3.12.2 Comparison with EI-AOM Accident 54 3.3.12.3 Conclusion 55 3 4. TECHNICAL ANALYSIS 57 4.1 INTRODUCTION 58 4.2 ENGINES AND PROPELLERS 59 4.3 FLIGHT CONTROLS 60 4.4 SYSTEMS 61 4.5 A DOOR STRIKE 62 4.6 A BIRD STRIKE 63 4.7 FUSELAGE FAILURE 64 4.8 METAL FATIGUE 66 4.9 FLUTTER 68 4.10 MAINTENANCE 70 4.11 REGULATORY ACTIONS 71 4.12 CONCLUSIONS 73 5. OPERATIONAL ANALYSIS 75 5.1 INCONCLUSIVE 1970 REPORT 77 5.1.1 Flight Reconstruction 77 5.1.1.1 Data available 77 5.1.1.2 Positioning and Timing 77 5.1.2 Unsolved Inconsistencies 78 5.1.3 Inconclusive 1970 Report 79 5.1.4 Consequences of this inconclusive Report 79 5.1.5 Operational Analysis Methodology 80 5.2 “MID-AIR COLLISION” SCENARIOS 82 5.2.1 Basic Observations 83 5.2.1.1 Military Activities in the St. Georges Channel 73 5.2.1.2 Control and Coordination of Air Activities 84 5.2.1.3 Air Collision Risks 85 5.2.2 Military Observations 87 5.2.2.1 Characteristics of the Weapon Systems existing in UK in 1968 87 5.2.2.2 Conditions for a mid-air collision to occur 88 5.2.3 “Mid-Air Collision” Scenarios 91 5.2.3.1 Scenario suggested by the 1970 Report : Collision with an 92 unmanned Aircraft 5.2.3.1.1 Description 92 5.2.3.1.2 Assessment 94 5.2.3.1.3 Conclusions 97 5.2.3.2 Alternative Scenario : Collision with a manned Aircraft 97 5.2.3.2.1 Description 99 5.2.3.2.2 Assessment 101 5.2.3.2.3 Conclusion 105 4 5.2.4 Conclusion of the operational Analysis of the “Mid-Air 106 Collision” Scenario 5.3 “NO RECOVERY” SCENARIO 107 5.3.1 Description 107 5.3.2 Assessment 109 5.3.3 Conclusion 110 5.4 “AS PER WITNESSES” SCENARIOS 111 5.4.1 Methodology 112 5.4.1.1 Witnesses‟ Statements 112 5.4.1.2 Flight Reconstructions 114 5.4.1.3 Two possible Scenarios 114 5.4.1.4 The Scenario “Disabled Flight” 115 5.4.1.5 The Scenario “Deviation from the Flight Plan” 115 5.4.1.6 Shannon R/T Transcript critical Analysis 5.4.2 Scenario “As per Witnesses/Disabled Flight” 117 5.4.2.1 Description 117 5.4.2.1.1 Track Reconstruction 117 5.4.2.1.1.1 Positioning of the Viscount 117 5.4.2.1.1.2 Timing 127 5.4.2.1.2 Aircraft Degradation Process 130 5.4.2.1.2.1 First Spin over Old Parish 130 5.4.2.1.2.2 Crew Reaction : Spin Recovery 133 5.4.2.1.2.3 Handling Capabilities of the disabled Aircraft 134 5.4.2.1.2.4 Second Spin over Kennedy Arboretum 139 5.4.2.1.2.5 Between Ballykally and Tuskar Rock 141 5.4.2.1.2.6 The Crash 148 5.4.2.2 Assessment 153 5.4.3 Scenario “As per Witnesses/Deviation from the Flight Plan” 154 5.4.3.1 Flight Reconstruction 155 5.4.3.2 Assessment 158 5.4.3.2.1 Filing-up of an IFR Flight Plan 158 5.4.3.2.2 Decision to divert from the Flight Plan 160 5.4.3.2.3 Preparation for Execution of the Diversion 160 5.4.3.2.4 Diversion Execution 161 5.4.3.3 Conclusions 164 5.4.4 Shannon R/T Transcript critical Analysis 166 5.4.4.1 Aim of the critical Analysis 167 5.4.4.2 Data available 168 5.4.4.3 Witnesses‟ Statements 169 5.4.4.4 Analysis 173 5.4.4.4.1 R/T Transcript 174 5.4.4.4.2 Shannon-London Telephone Line Transcript 178 5 5.4.4.5 Assessment 179 5.4.4.6 Conclusion 180 5.5 CONCLUSION OF THE OPERATIONAL ANALYSIS 182 6.0 CONCLUSIONS OF THE STUDY 185 6 ACKNOWLEDGMENT The International Team would like to acknowledge the valued cooperation and assistance from: IRELAND Mr Kevin B. Humphreys and the Staff of the Department of Public Enterprise Mr Gerry McCabe and Mr McStay, members of 1968 Investigation Commission Irish Aviation Authority Irish Air Corps Mr O‟Shea, Deputy Captain M. Reynolds Captain F. Ryan Captain Cronin UNITED KINGDOM Mr Ken Smart and Mr Dave King, of the AAIB Civil Aviation Authority (CAA) Ministry of Foreign Affairs Ministry of Defence (MOD) Defence Research Agency (DERA) Public Record Office (PRO) UK Embassy in Ireland BAe Systems, at Chadderton, Manchester Dowty The Brooklands Museum Mr E.D. Glaser, former test pilot in Vickers Mr E. McEwan, consultant 7 INTERNATIONAL ORGANISATIONS The International Civil Aviation Organisation (ICAO) and all Air Accident Investigation bodies who answered the call for relevant accident reports. 8 EXECUTIVE SUMMARY The accident which occurred in 1968 to Aer Lingus Viscount EI-AOM was never fully explained and was the subject of continuing controversy. In July 2000 the Irish Minister for Public Enterprise, Mrs Mary O‟Rourke T.D., commissioned this independent study of the accident circumstances. The study did not constitute a formal investigation nor a re-opening of the original investigation. The objective was to shed further light, if possible, on the cause or causes of the accident. Other than a limited amount of paperwork there was no longer any material evidence available. However the Team took advantage of a much longer in-service experience of the Viscount fleet than existed in 1968, and performed a deep analysis of several accidents considered as “relevant”, since they presented similarities with the Tuskar Rock accident.

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