An Indian Air Force AN-32 transport aircraft went missing on Friday morning with 29 people on board, during a routine weekly flight from Chennai to Port Blair.

A massive search and rescue operation is currently on in the Bay of Bengal to locate the plane, but initial investigations suggest it abruptly turned and plunged from 23,000 feet, approximately 280-km out at sea from Chennai.

Here’s all you need to know about the aircraft:

The AN-32 prototype took its maiden flight in July 1976. A Russian aircraft, it is considered to be one of the most reliable machines the IAF has in its inventory.

The AN-32 weighs around 16,800 kg and its maximum take-off weight is 27,000 kg. They can fly at a maximum speed of 530 kmph.

The aircraft can either transport 6.7 tonnes of cargo or up to fifty passengers, but is primarily used to ferry cargo, especially for mountainous and desert regions.

It also has an emergency beacon locator, which usually gets activated if there is a crash. The twin-engine aircraft has the ability to take off and land from small airstrips, and is designed to be used in both civilian and military situations.

According to aircraft manufacturer Antonov, the aircraft is fitted with modern cargo handling devices.

It has a cargo door with a ramp at the rear section of the fuselage. The ramp can be shifted under the fuselage for quick loading and unloading.

The aircraft flight navigation system and radio communication equipment enables performance of flights under adverse weather conditions, during the day and night, for local and international air routes.

Nearly 100 AN-32s are in service with the IAF. The aircraft can fly for up to four hours without refuelling and can also operate in all weather conditions.

There are 10 variants of the AN-32: An-32A, An-32B, An-32B-100, An-32B-110, An-32B-120, An-32B-300, An-32LL, An-32MP, An-32P firekiller and An-32B-200.

India’s AN-32 fleet is currently being upgraded and modernised with advanced avionics, communications systems, landing aids, new oxygen systems and better seats.

However, snags like pressure leak in port door, hydraulic leak in port wing root and sluggish throttle movement were reported in the aircraft just this month.

More than 240 AN-32 aircraft are currently being operated around the world, including in Bangladesh, Iraq, Sri Lanka and Colombia.

During the 1987-90 Sri Lanka operations, the aircraft flew over 70,000 missions without any mishap.

AN-32 aircraft have been involved in 11 accidents in India so far:

ʉۢ First crash Р1984: Aircraft vanishes half-an-hour before scheduled landing at Jamnagar; 17 missing

ʉۢ 22 March 1986: Crash while landing near Pathankot-Jammu; 19 dead

ʉۢ 25 March 1986: Missing without a trace over Indian Ocean; 7 missing

ʉۢ October 1988: Crash in Kanpur; 10 dead

ʉۢ 1989: Plane disintegrates mid-air while flying from Delhi to Orissa

ʉۢ July 1990: Crash near Ponmudi Mountain range; 6 dead

ʉۢ April 1992: Two AN-32 collide during a practice session in Ludhiana; 8 dead

ʉۢ March 1999: Crash while landing at Delhi airport; 21 dead

ʉۢ February 2000: Crash in Vijaynagar; no casualties

ʉۢ February 2009: Crash in mountains near Rinchi village, Arunachal Pradesh; 13 dead

ʉۢ September 2014: Accident while landing at Chandigarh Airport, no casualties

(sources: aviationsafety.net | baaa-acro.com)