New Delhi [India], Jun 5 (ANI): Congress on Wednesday asked the central government as to why the upgradation of AN-32 transport aircraft fleet was not completed, two days after a plane with 13 IAF personnel on board went missing over Arunachal Pradesh.

"Pray for safety and well-being of IAF personnel and crew of missing Aircraft AN-32. Sad to know that missing AN-32 had SOS Signal Unit that's OBSOLETE. Govt must tell- Why was upgradation of AN-32 not completed despite India and Ukraine agreement of 2009?" Congress spokesperson Randeep Singh Surjewala said in a series of tweets.

He said, "Govt and Def Ministry must also answer-: 1.Why was the AN-32 flying on that treacherous terrain when we have a better aircraft to fly on that route. 2. Why has the Govt not allocated sufficient defence budget to replace the AN-32 fleet?"Recalling that a similar incident happened earlier, Surjewala questioned as to why mitigating measures were not taken by the Defence Ministry.

"Govt and Def Minister must also answer-: 3. Despite a similar accident earlier of losing an AN-32 aircraft en route to Andaman and Nicobar islands and which was not tracked, why have mitigating measures not been taken by Defence Ministry?," Surjewala said.

On June 3, an IAF An-32 aircraft with 13 IAF personnel on board went missing after getting airborne from Assam's Jorhat. The aircraft was headed towards Menchuka Advanced Landing Ground in Arunachal Pradesh when it lost contact with ground authorities at 1300 hours.

Along with ground troops, Su-30MKI combat aircraft, C-130J special operations plane, and several choppers have been deployed to locate the missing aircraft. Indian Navy P-8I plane, ISRO satellites have also been pressed into service to find the missing An-32.

The Soviet-era aircraft was inducted into the Air Force in the 1980s and have been undergoing upgrades. The missing plane is not part of the upgraded An-32 fleet.

On July 22, 2016, an An-32 aircraft had gone missing while flying with 29 people on board. The aircraft was traveling from Chennai to Port-Blair in Andaman and Nicobar when it went missing over the Bay of Bengal. (ANI)