The pattern of domestic airlines receiving bomb threats to their flights continued for the fourth consecutive day as Air India got a threat for five flights - Mumbai-London (AI 129), Delhi - New York JFK (AI 119), a Chennai-Singapore and two domestic - IndiGo and Vistara threats for two flights each, were targeted in the similar manner on Thursday. Air India Express is also learnt to have got similar messages for six flights but a confirmation is awaited from the airline.

Four of these flights were still on the ground, while three were airborne at the time when the threats were received. The number of flights that have received such threats is now  close to around three dozen since Monday, forcing flight diversions and delays, piling up massive operational costs.

On Thursday a Mumbai-bound Vistara flight from Frankfurt with 147 persons on board was immediately taken to security checks on its arrival from Frankfurt following the Boeing 787 aircraft receiving a bomb threat. The flight, UK 28, was over Pakistan when it transmitted the code 7700, having 134 passengers and 13 crew onboard indicating a general emergency at around 6 am (IST) on Thursday, landed in Mumbai at approximately 7.45 am.

At the same time, an IndiGo flight operating from Istanbul in Turkiye for Mumbai also received a bomb threat and was taken to an isolation bay here for the security agencies to carry out a comprehensive security check. "The Vistara flight UK 028 operating from Frankfurt to Mumbai on October 16, 2024 was subject to a security threat received on social media," the airline said.

Given this persisting situation for the last few days, over half-a-dozen social media handles that issued hoax bomb threats to multiple Indian airliners this week, have been suspended or blocked by cyber security agencies till now. According to sources, the handles were "analysed" by a joint team of cyber, aviation security and intelligence agencies following which orders were issued to suspend these accounts as they continued to issue "mindless" threats.

About seven-eight social media handles, majority of them on microblogging site X, have been suspended or blocked since Monday, when these hoax bomb and terrorist attack threats started being sent to virtually all the Indian airliners for both their domestic and international route operations, the sources said. The agencies have also found some common lines and words used in these fake threats like "bombs", "blood will spread everywhere", "explosive devices", "this is not a joke" and "you will all die" and "bomb rakhwa dia hai" (Hindi for bomb has been placed) among others.

Sources said that the agencies, apart from getting police FIRs registered in each such hoax bomb messages case, have enhanced ‘cyber patrolling’ on the social media and the dark web to check for possible linkages or trends where threats are being posted online leading to grounding or diversion of the aircraft. The online surface is being scratched to find the primary email registration and geographical locations of these threat-issuing handles, some of which are possibly being prompted from overseas locations, the sources said.  These details are being shared with jurisdictional police departments, they said.

Notably, two common IPs from London and Germany have been traced. "The users have tweeted after using a virtual private network or virtual private network (VPN) - an encrypted connection over the Internet between a device and a remote server that’s aimed at masking one’s online identity," sources said.

At least 30 flights have been affected by these social media posted threat messages, all of which have come out hoax or false since Monday. In two cases, fighter jets of Singapore and Canada had to be scrambled to help the Indian planes that were carrying hundreds of passengers.

On Thursday, Vistara, in a statement, said that its Frankfurt-Mumbai flight received a security alert but landed safely here.The Vistara flight UK 028 operating from Frankfurt to Mumbai on October 16, 2024 was subject to a security threat received on social media," the airline said.

These fake threats have led to inconveniencing hundreds of passengers and airline crew apart from security agencies. They have taken a heavy toll on airline logistics and operational costs. A minor boy of 17 years of age from Chhattisgarh has been detained by the Mumbai Police in connection with the hoax bomb threats posted on social media platform X targeting three flights originating from Mumbai on October 14.

Meanwhile Civil Aviation Minister K Rammohan Naidu on Thursday said the ministry is looking at amending civil aviation regulations to ensure strict action is taken against incidents of bomb threats to airlines. "We are taking things seriously... We will take action," Naidu said about the bomb threats. At present, the actions against hoax bomb threat incidents are taken by the police under criminal laws.