The An-32 is a Soviet-designed twin engine turboprop transport aircraft used extensively by the Air Force

With the Indian Air Force An-32 missing for over 50 hours now, Sukhoi Su-30 fighter jets and C-130J transport planes will carry out search operations through the night, the government said today evening. Helicopter-led operations had to be called off due to poor light and will resume tomorrow morning.

On-ground search operations with teams from the Army, the Navy and Indo-Tibetan Border Police (ITBP) troops, supported by night-time sensors, will also continue through the night. The Air Force said the search area had been expanded despite challenges posed by vegetation, inhospitable terrain and poor weather.

The missing plane was traveling from Jorhat in Assam to a remote military landing strip in Mechuka in Arunachal Pradesh. The aircraft, which was carrying 13 people, was last in contact at 1 pm, sources had told NDTV. The normal flight time between Jorhat and Mechuka is about 50 minutes.

AN-32 search update: Search and rescue operations by helicopters have been called off for today due to low light, will resume tomorrow morning. Two SUs and C-130Js will be carrying out night missions to locate the missing aircraft. — ANI (@ANI) June 5, 2019

The Air Force has already deployed two Mi-17s and an Advanced Light Helicopter (ALH) in the search for the missing plane. Additionally, the P8i, a long-range maritime reconnaissance aircraft took off from INS Rajali in Tamil Nadu yesterday to join in the search.

In addition, ISRO satellites have also been pressed into service to map the area.

IAF: Search by IAF and Indian Army helicopters was adversely affected by weather during the day today. However, supported by Indian Army, Indian Navy, Police and State Administration the search efforts by ground teams and airborne sensors will continue through the night. https://t.co/jpAGmgLSae — ANI (@ANI) June 5, 2019

The terrain over which the plane was flying is mountainous and heavily forested; landing and take-off at Mechuka are extremely difficult. Coupled with erratic weather, the region is among the most inhospitable for air transport.

"The aircraft may have got entangled in low clouds. Flying in these areas is fraught with a measure of uncertainty," Air Commodore Prashant Dikshit (Retired) told NDTV.

As yet no signal from the plane's Search and Rescue Beacon, which has not been in production for 14 years, has been detected.

This distress signal was meant to have been picked up by a satellite belonging to Cospas-Sarsat, an international satellite-aided search and rescue facility. Additionally, a distress signal would also have been heard by search aircraft which had tuned into 243 MHz, the international air distress frequency.

In 2009, India signed a $400 million contract with Ukraine to upgrade and extend the operational life of its An-32s. The upgraded An-32 RE aircraft, 46 of which have been inducted, come equipped with two contemporary Emergency Locator Transmitters - the ARTEX C406-1 and the portable KANNAD 406AS; both are considered at least a generation ahead of the unit onboard the currently missing aircraft, which had yet to be upgraded.

The An-32 is a Soviet-designed twin engine turboprop transport aircraft used extensively by the Indian Air Force for over four decades. Since it joined the IAF fleet, the rugged planes used to ferry people and air-drop supplies have undergone several rounds of upgrades.