Two Indian Air Force pilots of a chopper accidentally shot-down in a friendly fire incident last year in J-K squadron leaders Ninad Mandavgane and Siddharth Vashisht have been posthumously awarded the Vayu Sena Medal for bravery. President Ram Nath Kovind on Saturday approved six Shaurya Chakras, 107 Sena Medals and four Vayu Sena medals for gallantry ahead of the 71st Republic-Day, defence officials said.