What is 'Squawk Code 7500'? Pilot's reaction to Air India 'hijack' scare explained

An Air India aircraft flying from Frankfurt to Delhi was diverted to Jaipur on Wednesday morning following a bomb threat, news reports said.  Details, including the number of passengers on board, could not be immediately ascertained during the time of compiling this article.

Reports claimed that the pilot used the 'Squawk Code 7500', which indicates unlawful interference, when the aircraft was in the Mumbai Flight Information Region (FIR). Subsequently, the plane was diverted to Jaipur.

Flight AI2030, operated using a Boeing 787-9 aircraft, made an emergency landing at Jaipur International Airport and was taken to an isolation bay for security checks. It took off from Frankfurt at 9:15 pm last night and was scheduled to arrive in Delhi at 10:40 am.

Assistant Commissioner of Police, Malviya Nagar, Shiv Dayal told news agency PTI that airport authorities had informed the police about the emergency landing of the Frankfurt–Delhi flight following a bomb threat.

Police sources said security personnel were checking the aircraft in the isolation bay, the PTI report said. Further details are awaited.

An official comment from Air India was awaited.

What is Squawk Code 7500?

In civil aviation, Squawk Code 7500 is an internationally standardised transponder code reserved exclusively to signal ongoing unlawful interference or an attempt to hijack the aircraft. When a flight crew enters ("squawks") 7500 into the aircraft's transponder, it immediately alerts air traffic control (ATC) and security agencies without needing a verbal radio call. For the unversed, a transponder is an electronic device that responds to radar interrogation and helps air traffic controllers identify and track the aircraft.

"An aircraft equipped with an SSR transponder is expected to operate the transponder on Mode A Code 7500 to indicate specifically that it is the subject of unlawful interference. The aircraft may operate the transponder on Mode A Code 7700, to indicate that it is threatened by grave and imminent danger and requires immediate assistance," the Airports Authority of India-linked Aeronautical Information Management states on its website.

How does ATC respond to a 7500 alert?

"When a pilot has selected Mode A and code 7500 and is subsequently requested to confirm his code by ATC he shall, according to circumstances, either confirm this or not reply at all. The absence of a reply from the pilot will be taken by ATC as an indication that the use of code 7500 is not due to an inadvertent false code selection," Aeronautical Information Management added.

Once the ATC receives the squawk alert, the code appears on air traffic surveillance systems, prompting controllers to treat the situation as a potential security incident.