Indian investigators have revealed that an Air India Airbus A319 which suffered a severe hard landing at Chennai was released to continue flying and not taken out of service for five days.
The aircraft had landed on Chennai's runway 25, with a descent rate of 400ft/min, touching down initially with a 1.6g impact before bouncing.
Five seconds later it contacted the runway again, this time with a descent rate of 912ft/min, and the impact was much harder at more than 3.5g.
Airbus considers a hard landing to be above 2.6g and a severe hard landing to be above 2.86g.
The Indian DGCA says an automatic load report was not generated, and the captain instead took a manual report from the computer – which showed a 1.59g impact – and consulted with a maintenance engineer.
It points out that only a verbal exchange took place and the matter was not recorded in the technical log.
After a visual inspection, and in the absence of a formal abnormal record, the aircraft was released to service.
It then operated for a further 30 sectors over the next few days until, on 3 October, a routine flight-operations monitoring analysis picked up the unusually-high 3.5g impact recorded during the landing.
Airbus subsequently examined the flight-data recorder information and classified the event as a severe hard landing, adding that preliminary assessment showed "exceedance" of loads on the fuselage, wings and main landing-gear.
The aircraft, a 2009 airframe, was eventually grounded in Bangalore on 4 October, five days after the incident.
Investigators have determined that the bounced landing resulted from the first officer's keeping the throttle in the 'climb' position instead of retarding it to idle – the position necessary to ensure spoiler deployment. The flare was initiated at 25ft but the first officer applied "excessive" pitch input, it adds.
This combination of thrust setting and pitch, which reached 5.6° nose-up, meant the aircraft became airborne again after the initial runway contact.
The captain noticed the incorrect thrust position and took over the controls, retarding the throttle, but did not realise the "quantum of bounce", says the inquiry, and the effort to smooth the touchdown failed, resulting in the second, hard impact.
None of those on board – comprising 59 passengers and six crew – was injured. The aircraft (VT-SCU) did not suffer damage, despite the severity of the landing.