Although the runway is short it was technically long enough. Investigators await flight recorder data for answers.
Until data from the aircraft's flight recorders can be downloaded, aviation community debate about the fatal TAM Airbus A320 overrun at São Paulo's Conghonas airport is centring on why the aircraft did not slow down as other aircraft landing before it had done.
The speed at which the aircraft overran runway 35L is not yet known, but witnesses say the aircraft "vaulted" traffic on the main highway at the base of the 15m (50ft) embankment on which the runway's end is raised, before colliding with buildings on the far side.
On 17 July TAM flight JJ3054 departed Porto Alegre for a 90min flight to Conghonas, arriving at 18:45 local time. The visibility was 6km (3.2nm) in light rain - but rain had been falling for days - with a headwind of 8kt (15km/h) and overcast at 700ft.
The runway surface was new but as yet ungrooved, and it had been reported by many pilots as slippery. The previous day a Panantal Linhas Aereas ATR 42-300 twin turboprop had skidded off the side but no-one was hurt.
TAM president Marco Antonio Bologna confirms the right engine thrust reverser had been deactivated because of a fault, but it was permissible to operate the flight.
The total tarmac surface, including overruns beyond the displaced thresholds at either end of 35L, is 2,066m. At the aircraft's declared 62.7t landing weight, in rain, with a total 186 people on board, theoretically the landing distance available should have been sufficient for an A320 landing in the touchdown zone at the correct speed.
The military-run air traffic control service has said it was too fast, and this theory will be tested when the US National Transportation Safety Board has downloaded data from the flight recorders.
Despite airport operator Infraero's protests that braking action was acceptable, the runway length allows little room for error in the wet.
Footage from fixed airport security video cameras of several landings before JJ3054, as well as the fatal landing itself, shows a limited field of vision, but the aircraft is seen travelling faster than those preceding it, and little if any deceleration is apparent.