Air India crash preliminary report: How detailed were earlier initial probe reports by AAIB?

Focus of earlier reports: basic facts

Preliminary reports in the past have mostly been limited to laying down the facts about the aircraft and crew, establishing the series of events leading to the accident, providing some basic analysis of the aircraft accident debris and site, and listing the steps taken so far in the investigation, shows an analysis of publicly available AAIB preliminary reports on investigations into accidents and serious incidents. However, it is worth noting here that the Ahmedabad air crash is a much bigger aviation disaster than anything that the AAIB has ever investigated in the past, and the preliminary report could provide critical insights into the accident and its most probable causes, even if it does not provide any definitive answer.

According to guidelines from the International Civil Aviation Organization (ICAO), investigators should release a preliminary report within 30 days of an air accident. However, Indian aviation experts pointed out that the country’s aircraft accident investigation rules have no such mandate and India is not bound to stick to the 30-day timeline for the preliminary report. However, given the global spotlight on this crash—the worst involving an Indian airline in at least four decades and the first fatal accident of the Boeing 787 aircraft globally—there is high likelihood of a preliminary report being released within the 30-day period. The final report should ideally be released within a year of the accident, and the AAIB tries to adhere to that timeline.

It is too early to jump to any conclusion, considering aircraft are extremely sophisticated and complex machines and detailed and painstaking investigations are required to ascertain the exact cause or combination of causes. The odds that an aviation accident has a single trigger are rare, and crashes usually have a series of things that go wrong together or one leading to another. That’s the reason why air crash investigations can take months, and at times even years, to conclusively state the cause or causes of the accident. And in this particular case, there aren’t any tell-tale signs that could prima facie establish a primary trigger for the crash.

Structure of earlier preliminary reports released by the AAIB

Most of the AAIB’s preliminary investigation reports reviewed by The Indian Express were four-five page reports divided into the following sections—general information, aircraft information, crew information, aerodrome information, weather information, brief description of the accident, wreckage and impact information, gathering of evidence, progress of the investigation, and interim recommendations, if any. They were mostly inconclusive, and limited to establishing the facts about the accident and the progress of the probe.

The general information section usually lists the aircraft type, registration code, country of registration, aircraft operator, date and time of the accident, place of accident, type of operation, and the phase of flight in which the accident occurred, among a few other details. The aircraft information section usually details the age of the aircraft, its certification, its recent maintenance and inspection records, any major snags or repairs, number of hours flown, details of the engines, a brief summary of the engine’s maintenance records, and number of hours operated on the engines.

The crew information section lists details of the two pilots, including the type of flying license, validity of their respective licenses, date and validity of their recent medical examinations, endorsements of aircraft types they are allowed to fly, their total flying experience, and their flying experience on the aircraft type involved in the accident.

Aerodrome information includes details of the airport, like its coordinates, runway length and configuration, operator, air traffic control services, and rescue and firefighting services. The weather information section provides details of local weather at the time of the accident.

The section on the accident flight description usually lays out the series of events prior to the accident. It describes the flight procedures that were undertaken, exchanges between the pilots and the air traffic control, and briefly narrates the incident with a few details of any warnings or alarms sounded in the cockpit and other events that might have transpired. It may involve inputs from statements recorded by the probe agency.

The section on wreckage and impact information provides details about the debris of the aircraft like the nature and extent of damage sustained, apart from listing observations from the wreckage’s onsite inspection. The evidence gathering section, which was not there in some interim reports, may briefly list the steps taken by the AAIB in gathering evidence along with details of key pieces of evidence having been collected and examined. The could include various aircraft components, flight data recorders, cockpit voice recorders, and any available footage, among others.

The section on the progress of the investigation essentially lists the status of the probe and the steps taken thus far in the investigation by the AAIB, and details the logs, records, data, statements, and other documents collected by the investigators. The AAIB also at times includes an interim recommendation section, which may include directions for various stakeholders in view of any significant finding during the initial investigation of the accident.