An IAF AN-32 aircraft carrying 29 people went missing over the Bay of Bengal.
The plane had taken off from Tambaram Air base in Chennai at 8:30 AM and was on the way to Port Blair in the Andamans.
The last radio contact was at 8:46 AM.
Officials said that the plane went off the radar at 9:12 AM. A search operation is underway.
The missing IAF AN-32
The Antonov AN32 aircraft
The AN-32 is twin engine turboprop military transport aircraft that was designed by former Soviet and now Ukrainian aircraft manufacturer Antonov State Company.
It was a redesign of the older AN-26, and was modified to withstand adverse weather conditions.
The aircraft can fly for up to 4 hours without refueling.
There are currently over 100 Antonov AN-32s in service with the IAF.
Made to withstand bad weather
The AN32 was specifically designed to be able to withstand extreme weather. This is vouched for by IAF pilots, including retired Air Force Officer Praful Bakshi, who said "These aircraft are very strong, they are used as supply planes for mountains and deserts."
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What went wrong?
How did the aircraft disappear?
The aircraft lost contact with base 16 minutes after take off.
Speculation is rife about what caused the aircraft to disappear, however several analysts suspect bad weather to be the primary cause.
Officials said that there was a rapid loss in altitude after the plane touched 23,000 feet.
AN32s are know for their resilience in bad weather, however the current fleet is undergoing refurbishment.
The missing people on board
Of the 29 people on board 6 were crew members and the other 23 were said to be family members and servicemen. However, no details are made public so far.
24 Jul 2016
No trace of IAF plane as search intensifies
The search for the missing AN32 transport plane intensified with Defence Minister Manohar Parrikar's arrival in Chennai.
However, the officials said there was no sign yet of any wreckage, as the depth of the sea at the estimated crash site is over 3500 meters.
29 Jul 2016
Underwater operations begin to locate missing IAF plane
The search operations for the IAF's missing AN32 transport aircraft have now begun focusing on underwater operations.
The Navy brought in several assets including submarines which could help locate the missing aircraft.
The navy also roped in INS Nirupak, equipped with an underwater vehicle and a camera to join the search.
02 Aug 2016
Missing AN-32 had no locator beacon
Sources revealed that the Indian Air Force's missing An-32's black box recorder was not fitted with an emergency underwater beacon locator.
This makes the search for the missing aircraft near impossible due to the depth of the sea and volatility of currents in the search area.
The IAF has now decided to fit such locators on all of the An-32s in its fleet.
11 Aug 2016
2 new vessels roped into aid AN32 search
Authorities have pressed into service an oceanographic research vessel Samundra Ratnakar of the Geological Survey of India and research vessel Sagar Nidhi of the National Institute of Ocean Technology to find the missing AN32 research aircraft.
So far there has been no trace of the missing aircraft.
Authorities expressed hope that the sub-surface capabilities of these 2 vessels could help locate the aircraft.
01 Sep 2016
Subhash Bhamre: No leads on AN-32, but search will continue
Minister of State for Defence Subhash Bhamre stated that there were no new clues or leads in the search for the missing AN-32 transport aircraft; however, search operations would continue in full swing.
He added that an inquiry has been launched into the probable causes of the crash.
The initial search operations were hampered by bad weather, costing valuable time in locating the aircraft.
06 Sep 2016
ROV to dive deep to locate AN32 wreckage
The National Institute of Ocean Technology is set to deploy a remotely operated underwater vehicle form its research ship "Sagarnidhi" on 12 September to locate the remains of the missing AN32 aircraft.
Officials seek to narrow the search down from the 15 possible locations to fewer, by using the ROV.
The ROV is said to be able to dive to a depth of 3500m.
15 Sep 2016
All AN-32 passengers presumed dead: IAF
The IAF said it arrived at the decision after "careful scrutiny of the circumstantial evidence available and in light of extensive search and rescue operations."
They added that families of victims have been informed so they could carry out insurance formalities.