Ryanair B738 at Rome on Nov 10th 2008, engine and landing gear trouble, temporarily departed runway

Last Update: December 20, 2018 / 16:36:51 GMT/Zulu time

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Incident Facts

Date of incident
Nov 10, 2008

Classification
Accident

Airline
Ryanair

Aircraft Type
Boeing 737-800

ICAO Type Designator
B738

On Dec 20th 2018 Italy's ANSV released their final report concluding the probable causes were:

The accident has been caused by an unexpected loss of both engines thrust as a consequence of a massive bird strike, during the go-around manoeuvre.

The loss of thrust has prevented the aircrew from performing a successful go around and has led the aircraft to an unstabilized runway contact.

The following factors have contributed to the event:

- the inadequate effectiveness of bird control and dispersal measures put in place by the airport operator at the time of the accident;

- the captain decision to perform a go around, when the aircraft was at approximately 7 seconds from touchdown. The above decision was significantly influenced by:

1. the lack of instructions to flight crew concerning the most suitable procedures to adopt in the case of single or multiple bird strikes in the landing phase;

2. the absence of specific training in the management, by the flight crew, of the “surprise” and “startle” effects in critical phases of the flight.

The ANSV summarized the sequence of events:

The aircraft established the first radio contact with Ciampino TWR communicating that it was 9 NM from the runway and stabilised on the ILS for RWY 15.

The aircraft, authorized and configured for the approach, was proceeding for landing, when, in very short final, it collided with a thick flock of birds (later identified as starlings).

The crew interrupted the landing procedure, initiating a go-around manoeuvre.

With both engines not delivering the necessary thrust and a flight attitude set for climbing, the aircraft rapidly lost speed and height, hitting the runway heavily in proximity of the taxiway “AC”.

Then, on first contact with the runway, which occurred with the main landing gear properly extended and with the lower part of the fuselage tail section, the main left landing gear detached from its anchoring during the landing run and the lower part of the left engine nacelle came into contact with the runway.

The aircraft stopped near RWY threshold 33.

The Fire Brigade vehicles immediately arrived at the aircraft and sprayed extinguishing foam around it, particularly in the area where the engine nacelle had come into contact with the runway.

The Captain then arranged for the disembarkation of the passengers and crew using a ladder truck from the right front door, with the addition of the right rear slide, later activated and used.

Two members of the crew and 6 passengers received minor injuries (back pain). The aircraft sustained substantial damage. "Not less than 86 bird impact points were identified on the radome and the front part of the fuselage, wing leading edges, flaps undersides, engine nacelles and landing gear. There were numerous and solid organic residues and bird feathers on stator and rotor blades of the engine fans."

With respect to bird control and bird monitoring the ANSV analysed:

The same BCU staff, however was already aware of the presence of starlings on the airport, from the days prior the accident (massive detection of about 1300 specimens, identified and dispersed in the evening of the day before).

In such context, it is appropriate to represent that the Captain pointed out to the ANSV that there were no NOTAMs informing about the presence of birds.

Given the extreme mobility and unpredictable behaviour of starlings, a more effective preventive action and, hence, to avoid the presence of birds, seems to be achievable through constant surveillance and dispersal, rather than through periodic inspections.

The ANSV analysed that it was impossible to unambiguously establish where the flock of starlings took off. However, it was possible to establish the point of impact through synchronizing FDR and CVR. The captain called out "Ahhh!" just when the aircraft was over the airport's perimeter fence, about 100 meters/330 feet ahead of the runway threshold bang sounds were heard and the crew applied TOGA.

The ANSV analysed: "The damage caused to the fuselage and flight controls by the bird strike did not affect the ability to control the aircraft; however the same bird strike severely affected the engines operations."

The ANSV analysed that the aircraft was fully stabilized while descending through 500 feet and stated: "Based on the Captain’s statement at the time of the interview, until the birds sighting and the bird strike, he believed that having considered the flight parameters, he could continue the approach and landing manoeuvre safely, the latter confirmed by the call «Continue»."

The ANSV continued:

At 06.55.51, at an altitude between 136 and 112ft radalt and a distance of 100 m from the runway threshold, almost simultaneously the Captain’s ordered «Go around», repeated three times and the TO/GA pushbutton was activated.

Based on the witness statements, it cannot be excluded that the Captain intervened instinctively on the throttles, anticipating, de facto, the action ordered verbally to the FO.

The throttles were positioned fully forward and the flaps commanded from 40° to 10°, overcoming the “detent” positioned in the 15° position to prevent retraction beyond the position requested for the go around manoeuvre.

From the statement made by the Captain, the selection was not voluntary nor was there any awareness of the flaps selection error.

This action is indicative of a reaction to an unexpected situation, typical of a phenomenon defined as “startle effect”.

On activation of the TOGA, when the throttles were full forward, the CVR CAM channel recorded a loud “bang”, a noise confirmed by the Captain during the interview and attributed to the impact with the flock.

The CVR evidence, the engine parameters and the position of the maximum concentration of the bird carcasses on the ground all indicate that the impact with the birds (or better the crossing of the flock which caused multiple impacts) occurred simultaneously with the activation, via the pushbutton, of the go around.

The go around activation coincided with the stall of both engines and the Captain’s verbal communication «Go around… go around…go around», when the aircraft was about 1 second from reaching the RWY 15 threshold and about 7 to 8 seconds from the normal point of contact with the runway, with the aircraft between 136 ft and 112 ft radalt, 149.5 kts and N1 62%.

On activation of the TOGA (06.55.51), the Flight Director symbols appeared indicating the necessary attitude for the go around, the FO set that attitude, requesting the flaps at 15°: both engines, instead of increasing rpm and providing the necessary thrust for the go around, experienced an N1 drop from about 62% to values around 40%; the vertical speed had a sudden reduction, causing a slight increase in the radalt (from 112 to 173 ft), until 06.56.01.
The above represented a substantial absence of positive rate of climb, which therefore did not induce the crew to take the subsequent actions provided by the checklist for go around, among these the landing gear retraction.

At 06.55.56, the flaps selection from 40° to 10° was commanded. This position was reached at 06.56.12, with the aircraft on the ground.
The FDR data show that the Captain took the aircraft control at 06.55.58, i.e. 7 seconds after activation of the TO/GA.

There were no communications between pilots regarding the handover of aircraft control until it started its deceleration run on the ground.

The Captain reported that in that circumstance he promptly intervened on the controls and noted that he did not have the thrust to continue the go around, then turned all his attention to “look outside”. He then realised he was inside the airport perimeter (Captain’s exclamation «On est dedans») and capable of bringing the aircraft, which had lost its alignment on the right likely due to asymmetric engines thrust at go around, to land on the runway.

The change of attitude and lack of engines thrust led also to a rapid airspeed drop and angle of attack increase.

From 06.56.01, the aircraft began to lose height, despite the nose up command still applied by the aircrew; the sink rate activation was recorded at 06.56.07, with a CAS of 122.75 knots, the stick shaker activation, at 06.56.09, corresponding to the max vertical speed of 1360 feet/min reached by the aircraft (indicative of an aerodynamic stall condition) and a progressive speed reduction and angle of attack increase, which reached values of 120.75 kts and 21° of AoA respectively, 1 second before the runway contact, when the aircraft was at a radalt height of 21 ft.

At 06.56.10, the aircraft touched ground (WOW commutation) with an attitude of about 10° pitch and -6° roll, an indicated speed of 120.75 knots, variometer of -1064 ft, vertical and lateral acceleration of 2.66 g and -0.45g respectively.

The aircraft had therefore lost height because of the aerodynamic stall, with the engine levers at maximum power position but without response from the engines and impacted the ground near taxiway “AC”, about half way along the total length of the runway, with a vertical acceleration of 2.66g.
Incident Facts

Date of incident
Nov 10, 2008

Classification
Accident

Airline
Ryanair

Aircraft Type
Boeing 737-800

ICAO Type Designator
B738

This article is published under license from Avherald.com. © of text by Avherald.com.
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