A Let L-410, OK-LAZ, was operated by Czech carrier Van Air Europe, on behalf of Citywing, an Isle of Man-based virtual airline that sold seats on flights operated by Van Air. On February 23, 2017, the aircraft was due to operate a return flight from Isle Of Man-Ronaldsway Airport (IOM) to Belfast City Airport, Northern Ireland. The scheduled departure time was 07:15 UTC and the return flight was scheduled to arrive back at IOM at 08:50. Overnight and into the morning of the 23 February, Storm Doris underwent explosive cyclogenesis. The centre of the storm moved rapidly through Northern Ireland in the early hours, across northern England and out into the North Sea by the early afternoon. Strong winds were forecast for the area. The surface wind at Belfast, where runways 04 and 22 were available, was reported at 06:20 to be from 230ø at 9 kt but, because they received no TAF for this destination, the pilots selected two alternate airports; Belfast International Airport and IOM. The latest weather information at IOM showed a wind from 230ø at 32 kt gusting to 45 kt, creating a maximum crosswind component of 22 kt. The relevant maximum demonstrated crosswind component for the Let L-410 is 19.4 kt and this was included in the ‘Performance Limitations’ section of the Airplane Flight Manual (AFM) but the aircraft operator did not apply a limiting component of crosswind to its operations. The only wind limit that was applied and used by the crew was 45 kt for ground operation. When the wind changed to 260ø at 39, gusting to 55 kt, the flight was delayed because this exceeded the ground operation limit, Departure At 07:50 the crew learnt the wind was from 290ø at 31 G 40 kt and as both these more recent reports were within the ground operation limit, they decided to depart, with 550 kg of fuel on board. Three passengers boarded and the aircraft taxied at 08:10. Shortly afterwards, at the request of Belfast City ATC, the crew were informed that the wind was from 320ø at 31 G 46 kt, and IOM ATC asked the crew for their intentions because Belfast City ATC had reported no other known aircraft movements. The crew elected to continue the flight and took off on runway 26 at 08:23 hrs, when the reported wind was from 290ø at 21 G 41 kt. The co-pilot was the Pilot Flying (PF) and the commander was Pilot Not Flying (PNF). No difficulties were encountered en route to Belfast. When the PNF contacted Belfast City ATC, he was told radar vectoring was available for an ILS approach to runway 04 and that the wind was now from 320ø at 28 G 43 kt. The PNF informed ATC they would make one approach but would go around if the approach was not stable. The crew reported afterwards that they experienced continuous moderate turbulence during the latter part of the approach. The final wind check, given after they had been cleared to land, was from 320ø at 35 kt. They judged that the aircraft operator’s stable approach criteria were met until the aircraft passed over the runway threshold, when turbulence de-stabilised the aircraft and they initiated a go-around. ATC reported that the aircraft went around from approximately 20 ft above the runway at 08:58 hrs and climbed straight ahead to 3,000 ft amsl, the standard missed approach procedure. The aircraft continued heading northeast until 09:01 hrs when the PNF informed ATC they would not make a second approach and would return to IOM. Return Once level at FL070, the PNF listened to the ATIS for the IOM, which stated runway 26 was in use, it was wet, and detailed the 0850 METAR, which noted that the wind was from 290ø at 28 kt. The PF briefed for an approach with the flaps set to 18ø, and a target VREF of 105 kt; with a “slightly right crosswind”. After the brief was completed he commented on the intercom that the wind was “not so challenging” at IOM but shortly after this ATC provided a special weather observation, timed at 09:12 hrs, which stated the wind was now from 310ø at 41 kt and gusting between 22 and 53 kt. When asked by ATC if they wished to make an approach, the PNF replied “of course”. The crew accepted radar vectoring for an ILS approach to runway 26, with the co-pilot remaining as PF. Before the aircraft was directed towards its final approach, ATC reported the wind was from 310ø at 43 kt but gusting between 23 and 63 kt. At 09:24, after the aircraft had become established on the ILS centreline and glideslope, ATC radioed clearance to land, with a reported wind of 300ø at 41 kt but gusting between 31 and 63 kt. While receiving this message, the crew were also presented with an aural “glideslope” caution and immediately after this the PF declared “1,000 ft stabilised”. While the PNF was adjusting the propeller rpm, another aural “glideslope” caution was annunciated and the PF immediately stated “correcting”. Following an automatically generated message stating the aircraft was at 500 ft agl, one further “glideslope” caution was annunciated and the PF responded saying “correcting, runway in sight”. The final wind check provided by ATC, approximately 35 seconds before the aircraft touched down, was from 300ø at 48 kt, but gusting between 32 kt and 63 kt. Landing Given the environmental conditions, ATC was concerned for the safety of the aircraft and its occupants when it landed, so the airfield Rescue and Fire Fighting Service (RFFS) had been placed on alert with two vehicles facing towards the runway, approximately 200 m from the touchdown zone. During the aircraft’s approach, ATC discussed the situation with the Isle of Man Civil Aviation Administration because another of the same operator’s aircraft had been blown onto its wingtip while taxiing in 2007, in winds greater than 45 kt, and both parties knew 45 kt was now the operator’s maximum ground operation limit. As the aircraft crossed the threshold it seemed unstable and it rolled considerably, causing the tip of the left wing (the downwind wing) to tilt down until it seemed in close proximity to the runway, before the wheels made first contact. The aircraft then bounced and rolled left again before touching down for a second time, on all three wheels. After travelling along the runway for approximately 20 m, the right mainwheel was seen to lift off the ground and nearby RFFS witnesses estimated the left wingtip rolled to within one metre of the runway surface. The crew seemed aware of this roll because, approximately nine seconds after touchdown, the PF stated “ailerons…good…too much roll”. After landing the commander took control and the co-pilot commented “taxi carefully with the wind”. ATC then stated the surface wind was from 300ø at 47 kt, but gusting between 32 kt and 63 kt and asked if they wished to taxi or to hold on the runway. The crew replied “we will try and taxi and if we can make it we will vacate, otherwise we need to leave the aircraft here”. The crew then accepted taxi instructions directing them towards the terminal but, 45 seconds later, as the aircraft was leaving the runway, ATC radioed to the crew, “direction from Isle of Man CAA, hold position.” The aircraft stopped facing into the wind. Both ATC and the Isle of Man Civil Aviation Administration later indicated that they were concerned that if the aircraft continued to taxi with the wind gusting to 63 kt an accident could occur. RFFS vehicles were positioned around the aircraft, to provide some screening from the wind, and a bus transferred the three uninjured passengers to the terminal building. The aircraft was later tied down until the wind subsided. Conclusion: The prime causal factor in this serious incident was the decision to land with a maximum crosswind component of 40 kt, which is approximately twice the maximum demonstrated certification value of 19.4 kt. In the view of the aircraft operator, there was no specific crosswind limit the crew needed to consider when deciding whether to operate the service or not. However, the OM Part A refers to a crosswind limit when it states: ‘For planning purposes an aerodrome shall be considered below minimum if the steady crosswind exceeds the prescribed limitations.’ and other evidence from the AFM and the OM indicates that the maximum demonstrated crosswind component of 19.4 kt was limiting. Several contributory factors were also apparent: 1) By only studying weather reports for six airfields and without referring to any meteorology charts, the crew had insufficient information to assess the prevailing weather conditions en route and the storm’s path. 2) The aircraft operator believed that a valid TAF could be disregarded upon the subsequent issue of a METAR that included a TREND forecast. 3) The aircraft operator did not provide adequate oversight to a flight in airspace affected by this storm. The commander did not refer to the available weather forecast charts and neither the OCC nor the FOM reviewed the situation with him, or suggested he seek guidance from the duty forecaster. 4) The fuel figures presented on the OFP did not account for the correct level of contingency fuel and did not allow for a realistic alternate routing. The aircraft had sufficient fuel for the sector, but the crew did not have as much extra fuel on-board as they believed they had, and the OM offered little guidance on the carriage of extra fuel when there was a possibility of widespread, adverse weather conditions. 5) The OFP only showed navigational and fuel information for the second of two selected alternates. However, the two Belfast airports are in close proximity so the lack of navigational information for the routing to the first alternate may not have been problematic in this instance. 6) The CVR evidence, that evolving threats did not precipitate verbal discussion between the pilots, indicates they had not been effectively trained in respect to CRM, and to threat management in particular. The OM appeared to lack guidance concerning the evaluation and management of threats, problem solving and decision making. 7) The approach became unstable before visual flight conditions were achieved, but the crew did not discuss this, and the required SOPs were not followed. 8) The limiting airspeed for flight with gear down and for flight with flaps extended was exceeded but no corrective action was taken. 9) The crew began taxiing the aircraft in a wind which was stronger than the wind which blew a similar aircraft onto its wingtip at IOM in 2007 and which exceeded the ground operation limit introduced after the 2007 accident.