india

Updated: Apr 15, 2019 06:56 IST

A recent civil aviation audit ordered by the government has revealed that the limits for some aircraft performance parameters were modified by operators in order to reduce the number of reported violations and improve safety records, according to Union minister Suresh Prabhu.

The Digital Flight Data Recorder (DFDR) installed in aircraft is used to gather statistics from a host of sensors that help in monitoring and reviewing flights. Airline operators have to mandatorily report the breach of safety limits to the Directorate General of Civil Aviation (DGCA), which also reviews the DFDR records of commercial airlines on an annual basis.

According to the special audit of airlines and airports – conducted between September and December last year – some DFDR parameter limits in aircraft were found to be set at values that were inflated or lower than manufacturer settings in order to avoid red flags. While Prabhu did not elaborate on the nature of values that were tweaked, experts said airlines are known to have changed criteria that determine hard landings and stabilised approach in flights. Maintaining a stable speed, descent rate and glide path before landing is commonly referred to as stabilised approach. DGCA mandates that any significant deviation should be announced by the operators.

“In the Air India Express crash in Mangalore, it was noticed that hard landing criteria set by Boeing was changed by the airline. Ideally, the minimum criteria set by manufacturer should not be changed, but airlines do that to keep the number of cases of violation low. Airlines can change the rate of descend, change in stabilised approach, speed limit, and many other things,” said Captain Mohan Ranganathan, an aviation safety expert.

The Air India Express jet crashed outside Karnataka’s Mangalore airport in 2010, killing 158 people. In its report on the incident, the DGCA said the aircraft was involved in a hard landing in the preceding 12 months. Air India did not respond to repeated phone calls. Another violation that the airport operators are known to avoid by changing DFDR values is “runway friction”. Exceeding limit can potentially lead to jets skidding on runways, according to experts. “If the runway friction value is low, then it is unsafe to operate during monsoon,” he said.

In response to an email query by Hindustan Times, the civil aviation minister said most of the issues raised in the audit and flagged to operators have been addressed since the report was prepared. “Most of the significant findings made during the audit have been closed. These areas are also regularly monitored by DGCA through surveillance inspections and regulatory audits as per the annual surveillance plan to keep the aircraft operations safe,” Prabhu said.

He added that DGCA carries out regulatory audits and surveillance inspections of various operations – scheduled airlines, non-scheduled operators, aerodromes and flying training institutes under its annual review.

“In September, additional special audits were ordered in the main areas like scheduled airlines, aerodrome operator, maintenance organisations and flying training institutes. Special audit of 11 scheduled airlines, 10 aerodromes, 11 approved maintenance organisation and 15 flying training organisations was carried out during the period September to December 2018. The findings were communicated to the operators,” the minister said.

While DGCA said preventive maintenance programmes were unavailable at many aerodromes, it pointed out that “adequacy of equipment’s/calibrated tools are not ensured for undertaking the task” and “inadequate manpower is available” at maintenance organisations.