On 8 February 2021, the crew of an Embraer 500 Phenom 100 (9H-FAM) being operated by Luxwing on a non-scheduled passenger flight from Venice to Paris Le Bourget lost control of the aircraft just before touchdown in normal day visibility. It dropped onto the runway with sufficient force to collapse the right main and nose gears and as it slid along the runway, a fuel-fed fire started. After just over 1000 metres, it exited the left side of the runway and pivoting around its yaw axis, it finally came to a stop. The airport emergency services were quickly on the scene and all three occupants were able to evacuate the aircraft uninjured.
An Accident Investigation was carried out by the French Civil Aviation Accident Investigation Agency, the BEA, using relevant downloaded data from both the CVR and the FDR. Both recorders stopped recording as the aircraft contacted the runway which was suspected to have been due to activation of a cut out switch designed to be triggered by a 5g vertical acceleration. Recorded ATC data, airport video surveillance recordings and various statements were also referenced.
The 40 year-old Captain had a total of “around” 3,625 hours flying experience of which 2,961 hours were on type. The 25 year-old First Officer had a total of “approximately” 625 hours flying experience of which all but 200 hours were on type. For both pilots, the investigated event occurred on their first flight of the day. Both pilots held commercial pilot licences (CPLs) and had obtained their EMB 500 type ratings at an Approved Training Organisation (ATO) in Finland. According to the operator's Training Manager, this type conversion training had included specific ‘Training Areas of Special Emphasis’ (TASE) on operations in icing conditions and on the relationship between the airframe de-icing system and the Stall Warning and Protection System (SWPS) which had been validated by its safety regulator.
The First Officer acted as PF for the flight for what was about a two hour flight to Paris. En-route at FL 340, the pilots discussed the forecast destination weather and the possibility of snow and/or runway contamination. The aircraft anti-icing system was tested and confirmed to be functioning normally and V speeds for an approach and landing in non-icing conditions were obtained from the AFM - VFS 121, VAC 102 and VREF 97. The destination weather was then obtained from the ATIS and it was noted that this especially included mention of “severe icing between 3,000 feet and 5,000 feet”. The Captain remarked that contrary to what the pre-fight forecast had indicated, “there was not going to be any snow” at Le Bourget and added in respect of the severe icing that “this was a common phenomenon at Le Bourget”. The approach briefing was then completed for an ILS approach to runway 27 with flaps in the “FULL” configuration and the AP engaged.
Once into the descent, cloud was entered at or before reaching 5000 feet QNH and the engine anti-icing and the windshield demisting/de-ice system were activated. Further clearance to 3000 feet followed and level at that altitude, the flight established on 27 ILS LOC as cleared with about 14 nm to go. The Captain then activated the airframe de-icing system and “confirmed he could see accreted ice breaking up” before deactivating it 21 seconds later whilst still in cloud.
The ILS GS was intercepted at around 8.5 nm and on transfer to Le Bourget TWR, landing clearance was given with a spot wind of 350°/ 4 knots. With the aircraft configured for landing, the landing checks were completed and the sub zero temperature cloud was exited. The Captain announced that he had runway 27 in sight and that he had switched off the engine anti-icing system, adding that “he could also have left it on as the temperature was 0°C”. The approach was stabilised and at 250 feet aal, at an airspeed of 100 KIAS, the AP was disengaged. Almost immediately, the Captain called that the aircraft was above the GS.
Five seconds after descending through 50 feet agl and over the beginning of the paved runway surface, the airspeed decreased from VREF -3 to VREF -7 and the recorded AoA increased from 10° to 28°. The aeroplane abruptly sank as the rate of descent increased from 700 fpm to almost 1000 fpm and roll instability occurred. The Captain called that he was taking control and attempted to begin a go-around but the stall warning activated, the aircraft stalled and made a very hard right-wing-low touchdown 10 metres beyond the displaced threshold.
The right main and the nose gear collapsed and the former punctured the fuel tank which led to a fire breaking out under the fuselage near the wing roots as the aircraft slid along the runway for just over 1000 metres before veering of the left side of the runway. It then pivoted around its yaw axis and finally stopped on a heading of approximately 160°. The airport RFFS was rapidly on the scene and extinguished the fire. Both pilots and the only passenger were able to evacuate the aircraft uninjured. The annotated illustration below shows the sequence once the aircraft had begun its slide along the runway.
The runway slide and final stopped position with the location of detached parts. [Reproduced from the Official Report]
Why It Happened
Conclusive evidence that airframe icing had led to the loss of control was evident for sometime after the accident had occurred as photographs of the wing and elevator leading edge taken three hours later and reproduced below show.
The left photo shows icing on the leading edge of the left wing (the white on the upper surface of the wing is residue from the fire extinguishant used) and the right photo shows ice on the leading edge of the elevator. [Reproduced from the Official Report]
It was found that this aircraft type could be fitted with one of two alternative avionics suites and that the one installed on the accident aircraft did not automatically have an ice detector installed and although an optional modification to add one was available, it had not been installed on the accident aircraft as was the case for around 90% of the affected fleet.
It was found that use of the AP during flight in severe icing conditions was prohibited and that the airframe de icing system must be activated whenever flight occurs in the presence of visible moisture if the Outside Air Temperature (OAT) is below 5°C even if there are no signs of ice accretion. Embraer also emphasises that whenever flying in icing conditions less than severe, “it is preferable to disconnect the autopilot in order to feel any possible consequences of ice build-up on the controls on the behaviour of the aircraft” and notes that use of trim in such conditions can preclude such awareness. The existence of an Embraer information video about flying in icing conditions aimed at EMB-500 Phenom 100 pilots was noted.
Embraer also pointed out that the activation threshold for the SWPS differs according to whether the airframe de-icing system is in use or not. With the system on, activation occurs at angles of attack of 9.5° (warning) and 15.5° (stick pusher) whereas with it off, the activation thresholds are respectively 21° and 28.4°. Based on FDR data, Embraer found by simulation that “the aural stall warning would have been activated twice, firstly at an altitude of between 1,000 and 850 feet and then just after 150 feet” with the stick pusher activated “shortly after flying through the radio-altimeter height of 50 feet”.
FDR data from just before just before impact showed that the aircraft as configured was “manoeuvring in speed and angle-of-attack envelopes where it was likely to stall in the event of ice contamination”. An examination of landing performance also found that a landing on either runway 25 or runway 27 at Le Bourget would not have been possible since the increased airspeed would have led to the LDA being less than that required. This fact was observed to be a result of abnormally significant operational constraints on landing performance in icing conditions on this aircraft type.
The Investigation noted that an accident to another EMB 500 Phenom100 at Berlin Schönefeld in 2013 had also been caused by improper operation in icing conditions.
Three Contributory Factors which may have led the crew to continue the approach without the activation of the airframe de-ice system rather than divert were identified:
- The operator's choice to use an aeroplane type for flights to destinations where icing conditions on approach are not unlikely, when the performance of this aeroplane type is degraded in icing conditions and becomes incompatible with the runway landing distances available, even though these runway landing distances provide substantial margins in the absence of icing conditions.
- The degraded landing performance of the Embraer EMB-500 Phenom 100 in icing conditions compared to performance in non-icing conditions. Crews thus frequently encounter situations where the destination airport is accessible with comfortable safety margins in non-icing conditions but becomes inaccessible in icing conditions.
- A deviation in the application of the de-ice/anti-icing system activation procedure, due to the landing performance penalties in icing conditions on this aircraft type, which does not appear to be limited to this crew or this operator. Instead of activating the wing and horizontal stabiliser de-ice system as soon as the temperature drops below 5°C in the presence of visible moisture, this system is only activated by the crews when they visually observe ice on the leading edges of the wing. It is then deactivated as soon as these crews note the absence of ice on the leading edges of the wings and consider that the risk of further ice accumulation before landing is low.
Three Safety Recommendations were made on the basis of the findings of the Investigation as follows:
- that the Brazilian Civil Aviation Authority (ANAC) in coordination with Embraer assess the improvement to safety that would be obtained by installing an ice detector on all EMB-500 Phenom 100 aircraft and the need to impose this modification on all Phenom 100 aircraft authorised for flight in icing conditions. [FRAN-2023-001]
- that the European Union Aviation Safety Agency (EASA) in coordination with constituent National Oversight Authorities and in the interest of promoting safety, make operators aware of the need to give better consideration in flight planning to the landing performance of aircraft which have significant differences in performance in icing and non-icing conditions. [FRAN-2023-002]
- that the European Union Aviation Safety Agency (EASA) consider revising the certification criteria (by applying special conditions, for example) when the differences between an aircraft’s performance in icing and non-icing conditions lead to operational constraints that are difficult for crews to manage. [FRAN-2023-003]
The Final Report was simultaneously published in both the definitive French language and in an English Language translation on 31 January 2023.