Have you ever noticed a VT sign on an aeroplane while travelling and wondered what it means? The code, which is generally seen just before the rear exit door and above the windows, is a legacy of the British Raj.The prefix 'VT' stands for ‘Victorian Territory and Viceroy Territory’, which is the nationality code that each aircraft registered in India is required to carry.As per rules set by the International Civil Aviation Organization (ICAO), each aircraft has to be registered in a country, where it is allotted a registration number. An aircraft can only have one registration in one jurisdiction. In simple words, the call sign or the registration code is for the identification of the aircraft.The making of codesThe registration number has two letters as the country code, followed by three letters of owners or the carrier's choice. For example, on IndiGo flights the registration VT is followed by IDV thus making the code VT-IDV. For Jet Airways, it is VT-JMV.Britain set the prefix 'VT' for India before the partition in 1929. The code for all airlines of its colonies started with V. However, countries like China, Pakistan, Nepal, and Sri Lanka changed their codes.While in India, the prefix has remained on the aircraft even after 93 years, which offends the right to dignity of citizens.Winds of change?Now, a public interest litigation (PIL) has been moved in Delhi High Court seeking direction to the central government to change the call sign ‘VT’. The plea, registered on Thursday, stated that even after years of independence, VT, a sign of slavery, still exists.The petitioner, Ashwini Kumar Upadhyay said that India is a sovereign country and hence cannot be a territory of the Viceroy. He also stated that in 2004, the aviation ministry approached the ICAO to change the code but no decision has been taken so far.Not the first attempt In a similar instance in August 2021, the Bombay High Court dismissed a plea filed by Vijaypat Singhania, former chairman emeritus of Raymond Group and a registered pilot, along with Pune-based businessman Vijay Sethi, seeking a change in the VT code.In December 2021, Minister of State for Civil Aviation Vijay Kumar Singh told the Rajya Sabha that the call sign 'VT' was assigned to India during the International Radiotelegraph Convention of Washington, 1927, signed in Washington on November 25. According to Singh, VT does not mean "Viceroy Territory" and call signs that are closer to India or Bharat such as I, IN, B, BH, BM, or HT are already assigned to other countries.Huge taskAccording to the government, changing the VT code will have a big financial implication.Such registration codes are a must for airlines to operate and repainting these on all airlines would ground much of the capacity and lead to travel chaos, too. Also documentation and changes as per protocol will take a lot of time.