Incident Overview

Description
At 11:52 hours (06:52 UTC) the Challenger 604 jet took off from runway 36 at Mal, Maldive Islands, for a flight to Al-Bateen, United Arab Emirates. Three crew members and six passengers were on board the airplane. At 07:20 UTC the airplane reached cruise level FL340. After entering Indian airspace (Mumbai FIR) the aircraft was cleared to fly to reporting point KITAL via route L894. At approximately 08:18 UTC the co-pilot radioed reaching reporting point GOLEM. At 06:55 UTC an Airbus A380-861 (A6-EUL) had taken off at Dubai Airport, United Arab Emirates, for flight EK412 to Sydney, Australia. The aircraft flew at FL350 with a southern heading. At 08:38:07 UTC the A380 had passed the Challenger overhead with a vertical distance of 1,000 ft. At 08:38:54 UTC the Challenger, with engaged autopilot, began to slightly roll right. At the same time a counter-rotating aileron deflection was recorded and fluctuation of the vertical acceleration began. In the subsequent approximately 10 seconds the airplane had a right bank angle of 4ø to 6ø. At 08:39:03 UTC the right bank angle began to increase. Within one second the bank angle increased to 42ø to the right. At the same time the aileron deflection to the left increased to 20ø and the vertical acceleration to 1.6 g. In the following second vertical acceleration changed to -3.2 g. At 08:39:04 UTC a lateral acceleration of 0.45 g to the right was recorded. The pitch angle changed from about 3ø to about 1ø, then within one second increased to 9ø and decreased again in the following second to -20ø. At the same time the FDR recorded a rudder deflection to the left reaching 11.2ø after about two seconds whereas the bank angle changed from 42ø right to 31ø left. Between 08:39:05 UTC and 08:39:10 UTC Indicated Airspeed (in knots) changed from approximately 277 KIAS to 248 KIAS. The N1 of the left engine of 95% began to decrease. The lateral acceleration then reached 0.94 g left, the autopilot disengaged, and a master warning, lasting seven seconds, was recorded. Both pilots had actuated the aileron to the right in order to stop the rolling motion. But the airplane had continued to roll to the left thereby completing several rotations. Subsequently both Inertial Reference Systems (IRS), the Flight Management System (FMS), and the attitude indication failed. Between 08:39:09 UTC and 08:39:41 UTC the FDR recorded a loss of altitude of approximately 8,700 ft. Large control surface deflections and acceleration were recorded. The speed increased and at 08:39:31 UTC reached approximately 330 KIAS. At 08:39:30 UTC the spoilers extended and 13 seconds later were retracted again. The N1 of the left engine had decreased to approximately 40% when the Interstage Turbine Temperature (ITT) began to increase and nine seconds later had reached 850ø. The left engine was shut off. At about 08:56 UTC the Pilot in Command (PIC) informed the air traffic controller in Mumbai of the occurrence, declared emergency, and reported their position, altitude and their intention to fly via KITAL to Oman. At about 09:15 UTC the crew restarted the left engine. Subsequently the airplane climbed to FL250. At about 09:56 UTC the autopilot was re-engaged. At 11:05 UTC the Challenger landed at Muscat Airport. The A380 continued the flight to Sydney and landed there at 19:58 UTC. The aircraft manufacturer determined that the Challenger’s airframe structure could not be restored to an airworthy state as it exceeded the airframe certification design load limits during the upset encounter.
Source of Information
http://omanobserver.om/private-jet-makes-emergency-landing-muscat/, http://www.atheer.om/archives/372100/%D8%A7%D9%84%D8%B7%D9%8A%D8%B1%D8%A7%D9%86-%D8%A7%D9%84%D9%85%D8%AF%D9%86%D9%8A-%D9%8A%D9%88%D8%B6%D8%AD-%D8%AD%D8%A7%D8%AF%D8%AB%D8%A9-%D8%A7%D9%84%D9%87%D8%A8%D9%88%D8%B7-%D8%A7%D9%84%D8%A7%D8%B6/, http://www.pprune.org/biz-jets-ag-flying-ga-etc/590638-challenger-beyond-repair-after-flight-upset.htmlhttp://omanobserver.om/private-jet-makes-emergency-landing-muscat/, http://www.atheer.om/archives/372100/%D8%A7%D9%84%D8%B7%D9%8A%D8%B1%D8%A7%D9%86-%D8%A7%D9%84%D9%85%D8%AF%D9%86%D9%8A-%D9%8A%D9%88%D8%B6%D8%AD-%D8%AD%D8%A7%D8%AF%D8%AB%D8%A9-%D8%A7%D9%84%D9%87%D8%A8%D9%88%D8%B7-%D8%A7%D9%84%D8%A7%D8%B6/, http://www.pprune.org/biz-jets-ag-flying-ga-etc/590638-challenger-beyond-repair-after-flight-upset.htmlPrimary Cause
The incident was likely caused by a combination of factors, with the most significant contributing element being the rapid and uncontrolled roll of the Challenger. The A380’s trajectory and altitude, combined with the Challenger’s erratic control inputs, triggered a chain reaction leading to the loss of control and subsequent maneuvers. The A380’s southern heading and subsequent passage of the Challenger overhead created a critical situation.The incident was likely caused by a combination of factors, with the most significant contributing element being the rapid and uncontrolled roll of the Challenger. The A380’s trajectory and altitude, combined with the Challenger’s erratic control inputs, triggered a chain reaction leading to the loss of control and subsequent maneuvers. The A380’s southern heading and subsequent passage of the Challenger overhead created a critical situation.Share on: