A Ryanair Boeing 737-8200 (EI-IGI) departed Barcelona for Bergamo with the anti-skid system inoperative following maintenance action for an anti-skid fault. During landing at Bergamo, all four main landing gear tyres burst and the aircraft came to a stop on the runway approximately 1,700 m from the threshold. There were no injuries to the 168 occupants, but the aircraft sustained substantial damage to wheels, brakes, landing gear, wing structures and fuselage, and the runway surface was extensively damaged.
The investigation found that the flight crew unintentionally applied braking before the speedbrakes had been manually deployed and the aircraft had fully settled onto the runway and generated the required Weight-on-Wheels (WOW) signals. With the anti-skid system disabled, this caused the wheel brakes to lock, resulting in all four tyres bursting and severe wheel/runway damage.
After touchdown the captain initially attempted to deploy reverse thrust, following habits developed from normal landings. Manual speedbrake deployment, which was required for an anti-skid-inoperative landing, was delayed. Brake pressure was applied approximately 4 seconds after touchdown, before the speedbrakes deployed. Near-maximum brake pressure was recorded on both brake systems. Wheel lock-up occurred, tyres burst, and the aircraft skidded down the runway. The FDR timeline showed brake application occurring before speedbrake deployment.
Flight crew contributing factors were the lack of simulator training for landings with anti-skid inoperative. Reliance on normal landing habits (“procedural memory” or motor programmes). The procedures did not clearly emphasise the critical sequence of speedbrakes first, nosewheel on ground and then braking. Differences between B737-800 and B737 MAX thrust reverser logic may have contributed to the captain focusing on reverse thrust rather than speedbrake deployment.
Maintenance contributing factors were maintenance troubleshooting identified a fault in wheel speed transducer #3, which affected only the INBOARD anti-skid channel. However, both INBOARD and OUTBOARD anti-skid channels were deactivated. Maintenance personnel did not follow the more specific AMM instructions requiring only the faulty channel to be disabled. This removed a significant safety mitigation that may have reduced damage.
Documentation and procedure factors were weaknesses in Boeing and operator documentation. MEL instructions were generic. Critical actions were spread across multiple manuals. No single document presented a clear chronological sequence of required actions. Warnings concerning brake application before speedbrake deployment were not sufficiently highlighted.
Following the event, the operator reduced the allowable anti-skid MEL dispatch interval from 10 days to a maximum of one flight cycle, required flight crews to consult a Duty Pilot before operating with anti-skid inoperative, produced an e-learning package using this event as a case study emphasising the correct landing sequence for anti-skid-inoperative operations during recurrent CRM training.
Maintenance were issued instructions requiring technicians to consult the applicable MEL and AMM whenever troubleshooting leaves an Hold Item List (HIL) open, improved procedures for urgent (AOG) parts dispatch, updated maintenance procedures relating to anti-skid fault isolation and proposed clearer wording requiring operational anti-skid channels to remain active.
ANSV issued three formal safety recommendations to Boeing. Introduce practical simulator training for anti-skid inoperative operations within Operational Suitability Data (OSD), both for initial and recurrent training. Provide a comprehensive, clearly sequenced anti-skid-inoperative landing procedure in the MMEL or related publications. Standardise maintenance instructions between the MMEL/MEL and AMM. Specifically, replace wording such as “should not be deactivated” with “must not be deactivated” regarding operational anti-skid channels. Remove ambiguity that may lead engineers to unnecessarily disable healthy anti-skid channels.
Photo Source: The ANSV report