A/HRC/36/55 Idlib and northern Hama. 11 The latter severely impacted the level of medical care which victims of chemical attacks received. V. The events of 4 April 7. On the morning of 4 April, the sky was clear. At 6.26 a.m., early warning observers12 reported that two Sukhoi 22 (Su-22) aircraft had taken off from Shayrat airbase, at least one of which was heading in the direction of Khan Shaykhun. Shayrat is a military airbase in Homs located approximately 120 kilometres south of Khan Shaykhun, and has been used by the Syrian air force throughout the conflict to launch attacks on Homs and Hama. Since late 2015, it is also used as a base by Russian forces. The Commission notes that two individuals interviewed by the OPCW claimed that on the morning of 4 April the early warning system did not issue warnings until 11 to 11.30 a.m., and that no aircraft were observed until that time. 13 The Commission has not gathered any information to support this claim, but rather the opposite, as detailed below. Eyewitnesses explained seeing a plane over Khan Shaykhun at around 6.45 a.m., and numerous interviewees recalled hearing messages from the early warning system 20 minutes prior to the strikes. As further examined below (paras. 17-18), 11.30 a.m. was the time when the al-Rahma medical point in Khan Shaykhun was attacked by airstrikes including cluster incendiary munitions, though not chemical weapons. 8. At around 6.45 a.m., interviewees recalled seeing an aircraft flying low over Khan Shaykhun, which is consistent with the airspeed of the aircraft and the distance that needed to be covered. In the span of a few minutes, the aircraft, identified by interviewees as a Su22, made two passes over the town and dropped four bombs. The Su-22 is easy to recognise, and difficult to mistake for anything else. Recognition features include a single vertical stabilizer, swing-wings, and flat intake mounted in the nose. 14 Satellite imagery, photographs, and video footage corroborate witness accounts that air delivered munitions hit the impact points of the four bombs. As previously found by the Commission, only the Syrian air force uses Su-22s,15 an aircraft which has no night-time capability. The Russian Federation and the international coalition do not operate this type of aircraft. It is therefore concluded that the Syrian air force carried out airstrikes on Khan Shaykhun at around 6.45 a.m. on 4 April. 9. Three of the bombs created loud explosions, causing damage to buildings though apparently only one casualty. Based on crater analysis and satellite imagery, the Commission was able to identify three conventional bombs, likely OFAB-100-120, and the remaining a chemical bomb. The chemical bomb landed in the middle of a street in a northern neighbourhood of Khan Shaykhun, approximately 150 meters from al-Yousuf park, close to a bakery and a grain silo, which interviewees explained was not operational and unused for any purpose after having been hit by an airstrike in 2016. Eyewitnesses further recalled how this bomb made less noise and produced less smoke than the other three bombs, which is confirmed by video footage of the attack. Photographs of the impact site show a hole, too small to be considered a crater, and the remnants of what appears to have been a Soviet-era chemical bomb. The small hole is indicative of a weapon which used a contact fuze and small burster to deploy chemical agents, with the kinetic energy of the bomb’s body creating most of the hole. Two parts of the bomb were found at the site, a large piece of the weapon body marked in green for chemical payload and a filler cap for chemical weapons. Although the Commission is unable to determine the exact type of chemical bomb used, the parts are consistent with sarin bombs produced by the former Soviet Union in the 250kg-class of bombs, which would have approximately 40kg of sarin, depending on the munition used. 11 12 13 14 15 A/HRC/36/55, paras. 63-65. Early warning observers comprise civilians who monitor aircraft flights to provide other civilians with advance warning prior to an airstrike. OPCW FFM report, paras. 5.27-5.29. A/HRC/34/CRP.3, para. 26. A/HRC/34/CRP.3, para. 27. 23