New Delhi: In a major scare on Saturday evening, an Indian Air Force aircraft ‘Meghdoot’ flying external affairs minister Sushma Swaraj from Trivandrum to Mauritius, on her way to South Africa, went incommunicado for 14 minutes.

The scare happened when Mauritian air traffic control and the crew of the Embraer 135 Legacy flying Swaraj — which was cruising safely — could not establish contact with each other for some time after the plane entered the island nation’s air space, reports the Times of India.

Mauritius then declared ‘INCERFA’ alarm, which in aviation parlance means an uncertainty phase wherein it is not known if the aircraft and its occupants are safe.
Soon after the story was first reported by TOI website, the AAI put out a press release confirming that Mauritius had indeed activated INCERFA or the first stage of emergency which lasted from 4.44pm to 4.58pm. Swaraj was accompanied by senior MEA officials including Secretary (Economic Relations) TS Tirumurti.

AAI said the plane took off from Trivandrum, where it had stopped for refuelling, at 2.08 pm for Mauritius. ‘Aircraft changed over from Indian airspace to Male ATC which then established contact with the aircraft at 4.44 pm IST. However, IFC 31 could not contact Mauritius ATC after entering Mauritius airspace. Mauritius ATC then activated INCERFA (the uncertainty phase). Later at 4.58pm IST, IFC 31 came in contact with Mauritius ATC and landed. Mauritius ATC activated INCERFA (uncertainty phase) without allowing the stipulated time period of 30 minutes to lapse from the time when aircraft last contacted ATC. This was perhaps done because the flight was carrying a VIP,’ said the AAI in its statement.
‘Over oceanic airspace, air traffic control (ATC) globally waits for 30 minutes to sound INCERFA for a plane if it does not contact it on entering its airspace of flight information region. In this case, the Mauritius authorities pressed the alarm button 14 minutes after the flight IFC-31 entered its airspace and contact could not be established with the plane,’ said a senior official of Airports Authority India (AAI), the parent organisation for ATC here.
The pilots of the Embraer, for which the alarm was sounded at 4.44pm, contacted Mauritius ATC at 4.58pm, after which everyone heaved a sigh of relief. The Embraer does not have a long range and Sushma, who is flying it from India to South Africa to attend BRICS and India-Brazil-South Africa (IBSA) ministerial meetings, had to take three refuelling or technical stops — Delhi-Trivandrum-Mauritius-South Africa.
A senior ATC official said communication over oceanic area is often problematic due to erratic VHF communication. ‘Sometimes pilots are unable or forget to contact the Mauritius area. That oceanic area has no radar coverage and everything depends on VHF/HF communication. Such places where VHF coverage is not good are known as dark zones,’ said the official.
The 14-minute long uncertainty phase (INCERFA) is first of the three emergency phases under International Civil Aviation Organisation’s Chicago Convention. The second is ‘alert phase’ (ALERFA) in which apprehension exists as to the safety of an aircraft and its occupants. The third is ‘distress phase’ (DETRESFA) wherein there is a reasonable certainty that an aircraft and its occupants are threatened by grave and imminent danger and require immediate assistance.
Luckily, the 14-minute-long scare involving Swaraj’s VVIP plane ended with the first stage itself.
‘Air Traffic Services (ATS) or the responsible Rescue Coordination Centre (RCC), as appropriate, will make the Emergency Phase declaration within the time frame specified for the trigger event. As an example, loss of radio contact with an aircraft under ATS control could result in declaration of the Uncertainty Phase within 10 minutes, the Alert Phase within 20 minutes and the Distress Phase within 30 minutes of the event whereas loss of radio contact with an aircraft not under ATS control might not trigger the Uncertainty Phase declaration until 30 minutes had lapsed with Phase upgrade occurring at 30 minute intervals,’ said aviation website SKYbrary.