The syllables 'VT' that you see on every Indian aircraft stands for 'Viceroy Territory', a legacy of the British Raj.
As per global rules set by the International Civil Aviation Organisation (ICAO), each aircraft has to be registered in a country, where it is allotted a registration number which has two letters as the country code, followed by three letters of owners or the carriers choice, like VT-123 in case of an Indian aircraft.
India was assigned the letters VT while it was still under British rule. In fact, the series VA to VZ were assigned to aircraft registered in all British territories.
This point was raised by BJP member Tarun Vijay in the Rajya Sabha during Zero Hour, who sought a change in the aircraft registration code.
He said, "Hindustan cannot be a territory of the Viceroy. Why India is continuing with VT code? VT should be changed right away."
He also demanded that an earlier decision of the government not to change the code should be amended.
The government had tried for several years to get the code changed over the last decade, wanting to replace it with IN for India, or BH for Bharat, or even HI for Hindustan. But none of these were available with the ICAO. The only options available are X or V.
Countries that changed their codes
Some countries did manage to change their codes after they gained independence, such as Fiji, Nepal and Pakistan.
After Independence, when India decided to retain VT, Pakistan adopted the initials 'AP' from the newly allocated call signs APA-ASZ. Sri Lanka, Nepal, Bhutan and Fiji use 4R, 9N, A5 and DQ respectively.
(With inputs from PTI)