New Delhi, Jun 22 (PTI) As the probe continues into the fatal Air India plane crash in Ahmedabad on June 12, former Director General of Aircraft Accident Investigation Bureau (AAIB) Group Captain Aurobindo Handa (Retd) spoke exclusively to PTI on the investigation process.

Handa said going by the visuals of the crash, the aircraft has been very badly damaged by fire and stitching together the evidences would be a tedious process.

"In all probability and in fairness, the investigation is likely to be a long drawn process," he told PTI.

Handa is also the former Chairman Accident Investigation Group (AIG) of ICAO -APAC Region.

During Handa's stewardship, AAIB had closed over 100 investigations, including the fatal crash of Air India Express plane which happened in August 2020 at Kozhikode, Kerala.

Following is the detailed interview Q. How much time do you envisage that the investigation into the Air India plane crash Ahmedabad would take? A. Annex 13 of the International Civil Aviation Organization (ICAO) as well as AAIB Rules mandate that any investigation should preferably be completed in less than a year.

Our investigators' endeavour to complete an investigation as quickly as possible so that remedial actions are instituted quickly through DGCA to avoid any recurrence.

However, going by the visuals of this accident, you would appreciate that this aircraft has been very badly damaged by fire. Therefore, corroborating and stitching together the evidences would be a tedious process. In all probability and in fairness, the investigation is likely to be a long-drawn process.

Q. How are the probable causes zeroed in during an aircraft accident investigation? A. Deep and detailed examination of meaningful evidences is a time-consuming process.

After analysing the data from the recorders, the investigators narrow down to the most probable systems and/or sub-systems that could have malfunctioned and/or contributed in a malfunction.

Step by step, each of the suspected causes for the accident are examined deeply and the unlikely causes are ruled out which is a rigorous process.

Basically, the process is driven by the 'method of elimination'.

It is akin to a physician going through pathological reports, X-Ray/MRI or other test reports before coming to a conclusion.

Q. What is the main aim of an aircraft crash investigation? A. As per Annex 13 of ICAO and AAIB Rules 2012 (as amended from time to time), the aim of the investigation is to find out the most probable root cause but not to apportion blame or liability.

Q. What are the broad steps involved in an investigation? A. The ICAO had come out with 'DOC 9756' or the Manual of Accident Investigation. Globally, the investigators follow this manual, which outlines detailed procedures to arrive at the most probable cause of an aircraft accident.

In addition, based on 'DOC 9756' and its own experiences, AAIB has prepared a document known as 'Procedure Manual' which contains the investigation process/procedures to be followed in India.

Q. What are the priorities for AAIB investigators after reaching the aircraft accident site? A. Obviously, when any unfortunate aircraft accident happens, the immediate focus of the 'first responders' such as airport staff, security personnel which includes CISF, NDRF and local police is to save lives.

AAIB takes charge of the activities as soon as its team arrives at the crash site and starts coordinating with the 'first responders' for the remaining work.

After cordoning off the general area, AAIB controls and regulates any movement at the crash site in order to make sure that the evidence is not lost inadvertently or tampered with deliberately.

AAIB's priorities are to look for survivors and/or save lives at the crash site, retrieve recorders, sift through the debris for any meaningful examination at a later date, and shift these meaningful debris to a safe and secure place.

AAIB investigators get divided into sub-groups and start segregating the debris into sub-groups such as flight recorders, airframe, propulsion, avionics and controls, among other elements.

The first and foremost task is the retrieval of recorders i.e. Cockpit Voice Recorder (CVR) and Digital Flight Data Recorder (DFDR).

Once the retrieval is affected, the next step is 'milking of raw data' from these recorders. The raw data is then converted into actionable and workable 'engineering parameters'.

Then, these engineering parameters are converted into graphs and charts for deriving meaningful and credible interpretation.

Q. How strong are India's capabilities in analysing the data during an aircraft accident investigation? A. India as a sovereign nation is quite well equipped to analyse recorders. AAIB, DGCA (Directorate General of Civil Aviation) and airlines also have their recorder labs in place.

In case, there is a need, AAIB can seek help from NAL (National Aerospace Laboratories), Bengaluru, HAL (Hindustan Aeronautics Ltd), Korwa, and LCA (Light Combat Aircraft) Project as they have excellent infrastructure and enough domain experts of international repute who can be co-opted to assist the aircraft accident investigations and render advice.

Also, if there is an iota of doubt that the milking of raw data from the recorders could result in erosion of data, the chief investigator under the guidance from the DG, AAIB can decide to take the recorders to their Original Equipment Manufacturer (OEM).

Aircraft manufacturers do not manufacture recorders and these are outsourced from other companies like Honeywell. PTI RAM TRB