On 5 December 2010 a Boeing 767-300 being operated by Qantas and departing Melbourne for Sydney in day VMC was following a Boeing 737-800 being operated by Virgin Australia which had also just departed Melbourne for Brisbane on the same SID and a loss of prescribed separation occurred. ATC became aware that the 767 was catching up with the 737 but were aware that it was in visual contact and therefore took no action to ensure separation was maintained. No TCAS activation occurred.