"
The buzz, in fact, has led to Flightradar 24 issuing a statement, saying when aircraft fly out of coverage, the positions on their website are shown according to estimates based on the latest received position, speed and track data."
So last known heading towards Pakistan aerospace before going dark/turning off transponder. But PAF should be monitoring them and working on minimizing their effectiveness.
Aviation Research Centre (ARC) the airborne wing of R&AW used to operate two Boeing 707-337C SIGINT platform in its inventory. They used the aircraft as a Strategic Surveillance Airborne System (SASS) to look deep into the enemy’s territory and gather intelligence.
ARC received two ex-Air India Boeing 707s in May 1987. The 707 sports IAF roundel on the top side of the aft fuselage and the fin flash – a rare illustration of this type in IAF colors. Due to the CIA’s involvement in the establishment of the ARC in 1962, they were equipped with a US mission suite by then-US contractor E-Systems which has since then been subsumed by Raytheon. The exact details of the systems installed on the aircraft were never revealed. They were deployed on ARC’s secret base in Charbatiya, Orissa which was also the location for CIA’s U2 flights during the 60’s.
The B-707s were extensively used during the Kargil conflict for ELINT operations. These aircrafts played an instrumental role in identifying enemy positions in the mountains and intercepting/ jamming enemy communications while flying at high altitudes.
One of the aircraft was upgraded in Israel after 2006. It’s characterized by the ‘cheek’ antenna fairings just behind the cockpit.
Both B-707s are currently parked at the Palam Air Force Base, Delhi gathering dust. These aircrafts are still classified, hence the personnel who operated them are prohibited from revealing details about them even now.