AAIB Bulletin: 5/2022 VQ-TIN AAIB-27492

67 ©Crown copyright 2022 All times are U TC AAIB Bulletin: 5/2022 VQ-TIN AAIB-27492 Pilot’s comments The pilot commented that he usually tests the landing gear warning horn with the annunciator press-to-test button on every flight. He added that he “tries to use” the Normal Procedures checklist in the aircraft on every flight but “probably didn’t use it” on the accident flight. The pilot believed he gave the passengers a safety briefing in the first aircraft but thought he also gave a briefing in the replacement aircraft. Passengers’ statements All the passengers were contacted by the AAIB. The passenger in the co-pilot’s seat stated that he did not remember any sounds associated with any pre-flight testing of any systems while on the aircraft. He added that once the pilot boarded the aircraft, it was taxiing in under 2 minutes. He also did not recall seeing the pilot use any checklists, nor did the pilot do an engine run-up/test prior to takeoff. There was no pre-flight safety briefing. Another passenger that was seated to the rear of the aircraft stated that she did not recall if the pilot provided a safety briefing but added that they were not shown a passenger safety card2 at any time. As with the departure, the passenger in the co-pilot’s seat did not see the pilot perform any checklists during the approach and landing. Additionally, he did not recall any noise associated with the landing gear being lowered. He was attentive to this on the return flight, where the noise was noticeable. He added that the first indication of a problem was the aircraft’s tail contacting the runway, followed by the propellers striking the runway. Once the aircraft came to a stop, he ordered his family members to exit immediately and did not recall the pilot offering any instructions. Smoke then entered the aircraft through an open window, creating fear of a possible fire or explosion. He then assisted his family out of the front left side window, before exiting himself. The passenger in the rear of the cabin initially tried to open the main cabin door to evacuate the aircraft. While the upper portion opened, the lower stairs did not fully lower as the landing gear was not down. She added that the pilot helped the other passengers out of the aircraft before following them out of the front left side window. Having initially had some difficultly opening the side exit she climbed out of the window in the partially opened main cabin door and was the last person out of the aircraft. Aircraft examination The maintenance organisation inspected the aircraft soon after the accident. In the cockpit, it was noted that the landing gear handle was in the down position. After subsequently lifting the aircraft and securing it on jacks, the main landing gear and the nose Footnote 2 Passenger safety cards were located in the rear of the passenger seat pockets. 68 ©Crown copyright 2022 All times are U TC AAIB Bulletin: 5/2022 VQ-TIN AAIB-27492 wheel were found in the up and locked position. There was also no damage to the landing gear doors, indicating they were in the up and locked position. When power was applied to the aircraft the landing gear indicator lights indicated landing gear up and locked. The unlocked light was not illuminated, nor was the landing gear in transit light. After the emergency blow down was activated the lights indicating transit/ unlocked illuminated followed by three green (down and locked) lights. It was subsequently discovered that landing gear warning horn was unserviceable. This was found to be due to a broken wire that routes close to the flap selector lever. This is an area that is in constant motion, as some of the horn’s wires move as the lever is moved. It was not determined when the wire broke, but it was likely to have failed when the flaps were selected on the landing of the previous flight or that of the accident flight. Analysis The pilot commented that he usually tests the landing gear warning horn on every flight but did not do so on the accident flight. After the accident it was discovered that the landing gear warning horn was unserviceable. While it could not be determined when it failed, had it been found to be unserviceable by conducting a pre-departure annunciator test, the pilot would have had an opportunity to seek engineering assistance, and possibly get it rectified, prior to departure. With the warning horn not working, there was no alarm available to the pilot on the approach when flaps 45 were selected to indicate that the landing gear was not down and locked. Had he heard the horn, he would have probably either lowered the landing gear while on the approach or initiated a go-around before making another approach with it selected down. The pilot said that he probably did not use the Normal Procedures checklist on the accident flight, and this was noticed by the passenger in the co-pilot’s seat. Checklists are there to assist pilots from forgetting to do essential actions during each phase of flight that, if not completed, could have had an adverse effect on the safety of the aircraft. It was likely that he was distracted and/or rushing due to the aircraft change, and this led to him not doing a thorough internal pre-flight check. There were conflicting accounts between the pilot and some of the passengers as to whether a safety briefing had been given, or whether a safety card was shown. Had there been no safety briefing given to the passengers, they would have been ill equipped to deal with any evacuation. Had the pilot been incapacitated this could have led to unexpected delays to the evacuation that may have led to serious injuries had there been a fire, or the damage been more severe. The pilot believed he lowered the landing gear prior to landing but did not use the checklist to confirm this. One passenger stated he did not feel or hear the sounds associated with the lowering of the landing gear, which he experienced on his next flight. While the landing gear handle was discovered in the down position it was more likely it was moved after the accident. However, it could not be determined when or by whom. 69 ©Crown copyright 2022 All times are U TC AAIB Bulletin: 5/2022 VQ-TIN AAIB-27492 Given the physical evidence discovered by the maintenance organisation and the statements of a passenger it was concluded that the landing gear was not extended prior to the landing. Conclusion The aircraft landed without its landing gear being extended. This was principally due to the pilot not using the Normal Procedures checklist prior to landing, to confirm it was down and locked. Checklists are an important tool that support a pilot’s airmanship and memory and ensure that all required actions are performed without omission and in an orderly manner. Not using or following them can have serious consequences as was seen in this accident. If they are not used it can potentially put an aircraft and its occupants at risk of experiencing a critical, adverse event.