APPENDIX Mi-172 HELICOPTER ACCIDENT, TAWANG REPORT OF ACCIDENT TO PAWAN HANS HELCOPTER LTD Mi-172 HELICOPTER VT-PHF ON 19TH APRIL 2011 AT TAWANG, ARUNACHAL PRADESH GOVERNMENT OF INDIA iii | 99 MINISTRY OF CIVIL AVIATION APPENDIX Mi-172 HELICOPTER ACCIDENT, TAWANG INTENTIONALLY LEFT BLANK iii | 99 CONTENTS Mi-172 HELICOPTER ACCIDENT, TAWANG REPORT OF ACCIDENT TO PAWAN HANS HELICOPTER LTD Mi-172 HELICOPTER VT-PHF ON 19TH APRIL 2011 AT TAWANG, ARUNACHAL PRADESH BY COMMITTEE OF INQUIRY COMPRISING Air Marshal (Retd) PP RAJKUMAR, PVSM, AVSM - Chairman Air Commodore (Retd) RAVI KRISHAN, VM - Member Wing Commander (Retd) RABINDER SINGH - Member Wing Commander VIPIN SHARMA - Co-opted Member Shri MJ SINGH, Deputy Director of Air Safety, O/o DGCA - Secretary GOVERNMENT OF INDIA MINISTRY OF CIVIL AVIATION APPENDIX Mi-172 HELICOPTER ACCIDENT, TAWANG INTENTIONALLY LEFT BLANK ii | 99 CONTENTS Mi-172 HELICOPTER ACCIDENT, TAWANG CONTENTS Serial No. Subject Page No. Abbreviation Used ……… x List of Photographs ……… xv 1. FACTUAL INFORMATION ……… 1 REPORT SHEET ……… 1 SYNOPSIS ……… 2 1.1 History of Flight ……… 3 1.2 Injuries to Persons ……… 8 1.3 Damage to Aircraft ……… 8 1.4 Other Damages ……… 9 1.5 Personnel Information ……… 9 1.5.1 Pilot in Command ……… 9 1.5.2 Co-Pilot ……… 11 1.5.3 Flight Engineer ……… 12 1.5.4 Cabin Crew ……… 13 1.5.5 Aircraft Maintenance Engineer ……… 13 1.6. Aircraft Information ……… 14 1.6.1 Aircraft Particulars ……… 14 1.6.2 Airframe Particulars ……… 14 1.6.3 Engine Particulars ……… 15 1.6.4 Fire Fighting System ……… 17 1.6.5 Fuel System ……… 17 1.6.6 Hydraulic System ……… 18 1.6.7 Landing Gear ……… 19 1.6.8 Emergency Locator Transmitter (ELT) ……… 20 1.6.9 Maintenance Arrangements ……… 20 1.6.10 Maintenance Records ……… 21 1.6.11 Load and Trim Sheet ……… 23 iii CONTENTS Mi-172 HELICOPTER ACCIDENT, TAWANG 1.6.12 Record of Previous Flights prior to the ……… 24 accident on 19.04.2011 1.6.13 Certification and Performance Category ……… 25 of the Aircraft 1.6.14 Size of Helipad required for Mi-172 ……… 26 as per Aircraft Manual 1.6.15 Anomalies observed in Rejected Take off ……… 26 Distances 1.7 Meteorological Information ……… 26 1.7.1 Area Weather Information ……… 27 1.7.2 Tawang Weather Information ……… 27 1.7.3 Satellite Imagery ……… 28 1.8 Aids to Navigation and Landing ……… 28 1.9 Communication ……… 28 1.10 Tawang Heliport Information ……… 29 1.10.1 Army Helipad ……… 31 1.10.2 Restrictions ……… 31 1.11 Flight Recorders ……… 32 1.11.1 Flight Data Recorder ……… 32 1.11.2 Decoding of FDR ……… 32 1.11.3 Sensor Unserviceabilities and Errors ……… 32 1.11.4 Analysis of Data ……… 33 1.11.5 Cockpit Voice Recorder (CVR) ……… 34 1.11.6 CVR Data ……… 34 1.12 Wreckage and Impact Information ……… 35 1.12.1 Wreckage Report ……… 35 1.12.2 Wreckage Relocated ……… 36 1.12.3 Impact Information ……… 38 1.12.4 Damage to Landing Gears ……… 39 iv CONTENTS Mi-172 HELICOPTER ACCIDENT, TAWANG 1.13 Medical and Pathological Information ……… 42 1.13.1 Shortcoming in the Conduct of Post-mortem ……… 42 1.13.2 Analysis of Injuries ……… 42 1.13.3 Injury Reports of PIC ……… 44 1.13.4 Injury Report of Flight Engineer ……… 44 1.14 Fire ……... 45 1.14.1 Fire Fighting Equipment available at Helipad ……… 45 1.14.2 Fire Fighting Equipment needed as per CAR ……… 45 1.15 Survival Aspects ……… 46 1.15.1 Origin of Black Smoke ……… 47 1.15.2 Factors that could have Reduced Smoke & Fire ……… 47 1.15.3 Emergency Exits ……… 48 1.15.4 Seating of Passengers ……… 51 1.15.5 Assistance to the Injured ……… 51 1.15.6 Wearing of Shoulder Harness ……… 52 1.16 Tests and Research ……… 52 1.16.1 Fuel Examination ……… 52 1.16.2 Updrafts/Downdrafts ……… 53 1.16.3 Explosives Investigation ……… 53 1.16.4 Oleo Legs Examination ……… 53 1.16.5 Wind Shear ……… 54 1.16.6 Experiments on Engine/MGB Oil & ……… 54 Hydraulic System Fluid 1.16.7 Animation of Flight Path ……… 55 1.17 Organisational and Management Information ……… 56 1.17.1 Government of Arunachal Pradesh ……… 56 1.17.2 Pawan Hans Helicopter Limited (PHHL) ……… 57 1.17.2.1 Observations on Mi-172 Operations in ……… 59 PHHL 1.17.3 Directorate General of Civil Aviation (DGCA) ……… 59 1.17.3.1 Flight Inspection Directorate of DGCA ……… 60 v CONTENTS Mi-172 HELICOPTER ACCIDENT, TAWANG 1.17.3.2 Licensing and Inspection of Helipads ……… 61 1.18 Additional Information ……… 62 1.18.1 Wet Lease Agreement ……… 62 1.18.2 Issues Pertaining to CAR ……… 63 1.18.3 Indian Aircraft Rule 160 ……… 64 1.18.4 Acceptance of Lowered Threshold of Safety ……… 65 1.18.5 Certain Relevant Features of Helicopter ……… 65 Aerodynamics 1.18.5.1 Helicopter Lift & Thrust ……… 66 1.18.5.2 Anti-torque Force ……… 66 1.18.5.3 Helicopter Flying Controls ……… 66 1.18.5.4 Helicopter Approach and Landing ……… 67 1.18.5.5 Ground Cushion ……… 67 1.18.5.6 Dynamic Roll Over ……… 68 2. ANALYSIS ……… 72 2.1 General ……… 72 2.2 Sequence of Events ……… 72 2.2.1 Pre-departure Schedule at Guwahati ……… 72 2.2.2 Initial Portion of Sortie ……… 72 2.2.3 Circuit ……… 72 2.2.4 Accident ……… 73 2.2.5 Control of Height on Approach ……… 74 2.2.6 Effect of Engine not being Switched Off ……… 74 2.2.7 Causes of Fire ……… 75 2.2.8 Other Likely Causes ……… 75 2.2.9 Use of Escape Hatch ……… 75 2.2.10 Passenger Inaction to Escape ……… 76 2.3 Flight Crew Performance ……… 76 2.3.1 Crew Resource Management ……… 76 2.3.2 Effect of Exceedence of AUW at Tawang ……… 76 vi CONTENTS Mi-172 HELICOPTER ACCIDENT, TAWANG 2.3.3 Incorrect Approach & Landing Technique ……… 78 2.3.4 Presence of other Helicopter ……… 78 2.3.5 Flight Engineer’s Actions after crash ……… 79 2.3.6 PIC’s Actions after crash ……… 79 2.3.7 Efficacy of Ground Staff to Suppress Fire & ……… 79 Evacuate Passengers 2.3.8 Duration of Fire ……… 80 2.4 Engine Response prior to Crash ……… 80 2.5 Flight Controls Response in Flight ……… 81 2.6 MGB/Rotor Response ……… 81 2.7 Effect of Size of Helipad ……… 81 2.8 Weather Conditions ……… 82 2.9 Sabotage Aspects ……… 82 2.10 Aero-medical Aspects ……… 82 2.10.1 Medical History of Flight Crew ……… 82 2.10.2 Pre-Flight Medical Examination ……… 82 2.10.3 Fatigue/Alcohol Consumption ……… 83 2.10.4 Survivors ……… 83 2.10.5 Adequacy of Post-mortem ……… 83 2.11 Recorder Analysis ……… 84 2.11.1 FDR Analysis ……… 84 2.11.2 CVR Analysis ……… 84 2.11.3 Correlation of Data of Recorders ……… 84 2.12 Why did the Accident Take Place? ……… 84 3. CONCLUSION ……… 87 3.1 Findings ……… 87 3.2 Cause of the Accident ……… 89 3.2.1 Direct Causes ……… 89 3.2.2 Contributory factors to the Accident ……… 89 vii CONTENTS Mi-172 HELICOPTER ACCIDENT, TAWANG 4. RECOMMENDATIONS ……… 91 4.1 For The Operator -Pawan Hans Pvt Ltd. ……… 91 4.2 For DGCA ……… 91 4.2.1 CARs ……… 91 4.2.2 Concessions/Filing of Differences ……… 91 4.2.3 Inspection of Helipad Safety Services ……… 92 4.2.4 Rule 160 ……… 92 4.2.5 Category A Certification for Mi-172 ……… 92 4.3 For Govt of Arunachal Pradesh ……… 92 4.3.1 Periodic Inter-action with DGCA ……… 92 4.3.2 Training on Crash Fire Fighting ……… 92 4.3.3 Licensing of Helipads ……… 92 4.4 For Ministry of Civil Aviation .......... 93 4.4.1 Licensing of Helipads ......... 93 4.4.2 Flight Inspector .......... 93 5. APPENDIX ……… 95 6. ACKNOWLEDGEMENT ……… 98 oooooooooooooooo viii