SAFE WINGS Issue 49, JUNE 2016 This issue SOMATOGRAVIC ILLUSION GULF AIR FLIGHT 072 TATARSTAN AIRLINES FLIGHT 363 OTHER SUSPECTED SOMATOGRAVIC ILLUSION
SAFE WINGS June Edition 49 EDITORIAL We have arrived at the beginning of yet another monsoon season. We experience rains in other parts of the world too, for example Singapore and Kuala Lumpur have rains throughout the year. Yet, in spite of the precautionary recurrent training on Adverse effects of the Indian monsoon season, year after year incidents keep repeating during this season. They are not isolated to any particular airline but it is an Industry wide phenomenon. We need to reiterate to ourselves that we should not become part of that statistic. Somotogravic illusion is suspected to have caused a number of accidents and one such suspected cause is the recent Fly Dubai accident at Rostov. In this issue we have featured an article on this subject.. ACKNOWLEDGEMENTS The posting of stories, reports and documents in this magazine does not in any way, imply or necessarily express or suggest that all the information is correct. It is based on details gathered from various sources and is for information purpose only. The Flight Safety Department is making this material available in its efforts to advance the understanding of safety. It is in no way responsible for any errors, omissions or deletions in the reports. 1 P age
June Edition 49 SAFE WINGS SOMATOGRAVIC ILLUSION The somatogravic illusion is a vestibular illusion which is prevalent during high accelerations/ deccelerations when a pilot has no clear visual reference. The word Somatogravic is derived from somato meaning of the body and gravic meaning pertaining to the gravitational force and is a strong pitching sensation (either up or down) when the body is exposed to either high acceleration or decelerations. This illusion is due to the interaction of unnatural accelerations (such as those experienced in an aircraft) on our Otolith Organs, specifically our utricle. Normal Operation of the Balance System Our vestibular system uses the Otolith Organs (the sacculus and the utricle) to detect accelerations. Our sacculus detects accelerations in the vertical plane and our utricle detects accelerations in the horizontal place. Our Otolith Organs are designed to help us sense tilt (i.e. if our head is upright). If we tilt our head backwards, the hairs in our utricle bend backwards (due to the acceleration force of gravity) and so sense this as a tilt (vice versa for a forward head tilt). Forces acting on head. 2 P age
SAFE WINGS June Edition 49 Confusing Signals If we accelerate rapidly in the horizontal plane this has a very similar effect on the hairs in the utricle they bend backwards. As far as our brain is concerned this is the same sensation as the movement of a head tilt. This concept is shown in the figure above. Note how the hair (or macula) movement for head tilt backward and acceleration forward are exactly the same. Consequences for Aviation In aviation we are faced with the combination of rapid acceleration and reduced/no visual cues (i.e. IMC and/or night flying). As we no longer have the benefit of our visual system to resolve the ambiguity, our brain uses the signals it is receiving and interprets them as a tilt. The net result is a tilt back (i.e. pitching up) sensation under acceleration, and a tilting forward (i.e. pitching down) sensation under deceleration. Perceived and Actual Flight Paths due to the Somatogravic Illusion Typically this occurs during the missed approach or go-around segment of a flight at night or in IMC. Speed is slow, power is rapidly applied and the aircraft then accelerates rapidly. As no visual cues exist, this generates a strong tilt back sensation which the pilot interprets (incorrectly) as a rapid pitching up sensation. Despite this perception the aircraft may still actually be in a level attitude or only a 3 P age
June Edition 49 SAFE WINGS slight climb. This is the somatogravic illusion. The pilot will then push forward on the control column to control this (imaginary) climb thinking they are lowering the aircraft nose back to level flight, when in actual fact they are lowering the nose into a dive. As the aircraft nose lowers, the aircraft continues to accelerate, generating additional pitch up sensations, causing the pilot to lower the nose even further. Tragically, this illusion normal ends with the pilot commanding the aircraft into a high speed steep dive and contact with the ground quickly ensues. In the early days of launching Navy aircraft from aircraft carriers at sea, the somatogravic illusion which is quite intensely felt by the pilots during the launch - has led to many accidents. The pilots reacted to the illusion by pushing the control stick forward and pitching down, while the aircraft was actually horizontal or climbing. As a consequence many dived into the sea in front of the moving ship. Whilst not common (as high horizontal deceleration forces are rare in aviation), the reverse also applies. If a strong deceleration force is present and no visual cues exist, the pilot may experience a false pitch down sensation forcing them to raise the nose, possibly to the point where the aircraft stalls. The somatogravic illusion also played an important role in the accident of an Airbus A320 of Gulf Air that crashed into the Gulf of Bahrain. The captain, acting as pilot flying, initiated the go-around (strong linear acceleration!) flying in the direction of the gulf. It was night and in the dark he had no visual cues. However, neither did he monitor his instruments for the correct go-around pitch (nor did the co-pilot). He experienced a strong illusion of pitching up, causing him to push the control stick forward for a certain time, instead of keeping it fully aft, as was the prescribed procedure. While the captain still had a false nose high perception the airplane was already descending to the water. It crashed, leaving no survivors. 4 P age
SAFE WINGS June Edition 49 Gulf Air Flight 072 Gulf Air Flight 072 was a scheduled flight from Cairo to Bahrain. On 23 August 2000, the Airbus A320 serving the flight crashed into the shallow waters of the Persian Gulf 5 kilometers from the airport. All 143 on board the aircraft were killed. Accident The A320 with 143 passengers and crew on board approached Baharin and a go around was attempted. While carrying out a turning climb, the aircraft entered a descent at 15 degrees nose down. The aircrew did not respond to repeated GPWS warnings and approximately one minute after starting the go-around the aircraft disappeared from radar screens. There were no survivors. Investigation The investigation showed that the accident was the result of a fatal combination of many contributory factors, both at the individual and systemic levels. 5 P age
June Edition 49 SAFE WINGS 1. The individual factors particularly during the approach and final phases of the flight were: a. The captain did not adhere to a number of SOPs, such as: i. significantly higher than standard aircraft speeds during the descent and the approach ii. not stabilising the approach on the correct approach path; performing an orbit, a non-standard manoeuvre, close to the runway at low altitude iii. not performing the correct go-around procedures. b. In spite of a number of deviations from the standard flight parameters and profile, the first officer (PNF) did not call them out, or draw the attention of the captain to them, as required by SOPs. c. A perceptual study indicated that during the go-around after the orbit, it appears that the flight crew experienced spatial disorientation, which could have caused the captain to perceive (falsely) that the aircraft was pitching up. He responded by making a nose-down input, and as a result, the aircraft descended and flew into the shallow sea. d. Neither the captain nor the first officer perceived, or effectively responded to the threat of increasing proximity to the ground, in spite of repeated hard GPWS warnings. 2. The systemic factors, identified at the time of the above accident, which could have led to the above incidents were insufficient oversight and training. 6 P age
SAFE WINGS June Edition 49 Tatarstan Airlines Flight 363 History Of Flight Tatarstan Airlines Flight 363 was a scheduled domestic passenger flight, operated by Tatarstan Airlines from Moscow to Kazan, Russia. On 17 November 2013, at 19:24 local time (UTC+4), the Boeing 737-500 crashed during an aborted landing in Kazan International Airport, killing all 44 passengers and 6 crew members on board. According to the official investigation report, the crash was a result of the pilot failing to recover during a go-around procedure. The Crash Flight 363 took off from Domodedovo International Airport in Moscow at6:25 p.m. local time, destined for Kazan International Airport, some 800 kilometres (500 mi) east of Moscow. Whilst on final approach to Kazan International Airport, the crew initiated a go-around due to an unstable approach but crashed onto the runway in a 7 P age
June Edition 49 SAFE WINGS 75-degree-nose-down attitude, at a speed of 242 knots, moments later, and exploded upon impact with the ground. All 44 passengers and 6 crew members were killed; there were no casualties on the ground. High winds and cloudy conditions were reported at the airport at the time of the crash. Investigation During the final approach the flight crew observed that the aircraft was not lined-up properly relative to the runway, reported to the ATC and started to go-around using the TOGA (Take Off / Go Around) mode. The engines reached thrust level close to full. The crew retracted the flaps from 30 degrees to 15 degrees position. Affected by the upturn moment generated by the engine thrust, the aircraft started to climb, reaching the pitch angle of about 25 degrees. Indicated airspeed had started to decrease. The crew retracted the landing gear. Since initiating the go-around maneuver up to this moment the crew did not perform control actions through the yoke. After the airspeed decreased from 150 to 125 knots, the crew started control actions through the yoke, pitching nose down, which has led to stopping climb then starting descent and increase of the airspeed. Maximum angles of attack have not exceeded operational limits during the flight. After reaching the altitude of 700 meters, the aircraft started a steep nosedive, with the pitch angle reaching 75 by the end of the flight (end of the recording). The aircraft collided with terrain at high speed (exceeding 250 knots) and with highly negative pitch angle. About 45 seconds passed between the moment of starting go-around maneuver and the moment the recording stopped, the descent took about 20 seconds. 8 P age
SAFE WINGS June Edition 49 The engines were operating up to the collision with terrain. The go-around was necessitated by a positional error in the navigation system, a map drift. Other suspected Somatogravic Illusion Accidents Armavia Flight 967 Flight origin Destination : Zvartnots Airport, Yerevan : Adler Airport, Sochi Armavia Flight 967 A320, was a flight operated by Armavia, the largest international airline of Armenia on May 3, 2006, from Yerevan in Armenia to Sochi, a Black Sea coastal resort city in Russia. The aircraft crashed into the sea while attempting to conduct a go-around following its first approach to Sochi airport, killing all 113 aboard. 9 P age
June Edition 49 SAFE WINGS Afriqiyah Airways Flight 771 Afriqiyah Airways Airbus A330-202 during a go around following a nonprecision approach to Tripoli, Libya, on May 12, 2010. The flight crew did not acquire any visual ground references before the approach was started. The aircraft started its final descent for landing too early. The aircraft had descended to 280 feet above ground when the terrain awareness and warning system sounded in the cockpit. The captain ordered a go-around and the autopilot was turned off. The first officer put the nose of the aircraft up for 4 seconds and the thrust levers were set to go-around power. The aircraft pitched up to 12.3 nose up and the flight crew raised the landing gear and flaps. Shortly thereafter the co-pilot started making nose down inputs which caused the aircraft to pitch-attitude to reduce to 3.5 nose down. (The co-pilot could have been focused on the aircraft's speed, rather than its altitude.) The go-around pitch attitude was not maintained and the instructions from the flight director were not followed. (The report says that fatigue could have played a role in causing the first officer to focus solely on the airspeed.) The captain and the first officer were making inputs to the aircraft's side stick at the same time (although the dual inputs were not sufficient to trigger a dual-input warning). This action led to confusion on who was flying the aircraft. The ground proximity warning system sounded as the aircraft lost more height and the co-pilot responded with a sharp nosedown input. The aircraft crashed killing all on board except one passenger. 10 P age
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