The Fire Services Department is investigating whether human error that led to the 18-minute delay in upgrading a blaze in Cheung Sha Wan last week was to blame for the death of a veteran fireman. The department's deputy director, Andy Chan Chor-kam, yesterday confirmed a mistake was made and said new measures to prevent a repeat had been introduced. An investigation showed that a message sent by a frontline commander requesting that the blaze be upgraded to a No3 fire was deleted by an operator at the communication centre, the department said. Chan said the discovery that the message was deleted was made 18 minutes later, when no reinforcements had arrived and the commander checked with the centre. Fires in the city are rated on a scale of one to five according to their seriousness. Extra firemen and fire engines are deployed when a blaze is upgraded. Chan described the incident as rare and pledged a full investigation. He said the operator involved was not suspended and needed to explain to the special investigation team why and how he deleted the message. The deputy director said the team set up to investigate the cause of the fire and the death of senior fireman Yeung Chun-kit, 47, would look into whether the mistake caused the fire to spread and affected firefighting strategies. 'They will also investigate whether the delay was a factor that led to the death of our colleague,' Chan said. Results of the investigation would be submitted to the Coroner's Court, he said. The blaze broke out in a fifth-floor knitting factory in the nine-storey Lai Cheong Factory Building at 8.19am on May 8. At 9.32am, the commander at the fire scene sent a text message to headquarters through a mobile data terminal on a fire engine requesting the fire be upgraded to No3. The terminal is linked to the communication and mobilising system in the Tsim Sha Tsui headquarters. But the message was deleted by one of the centre's operators 41 seconds after he received it. As no reinforcements arrived, the commander at the scene checked with the communication centre and discovered the error at 9.50am, and the fire was upgraded. Yeung and teammate Ng Wai-lam, 33, from the Lai Chi Kok Fire Station, were among four two-member teams with breathing equipment sent into the blazing knitwear factory at 10.25am. Ng was found unconscious on the floor shortly before the blaze was upgraded to a No4 fire at 10.58am. But Yeung was not found until 12.10pm. He was lying with his legs trapped under rubble 10 metres from the entrance. The blaze was extinguished at 2.24pm. Two other firemen were injured. Chan said the investigation showed that the computer communication and mobilising system, which has been in use since 2005, did not malfunction. The system cost HK$700 million. To avoid a repeat of the mistake, he said frontline officers were reminded to use a walkie-talkie or mobile phone to request that a fire be upgraded. The department would ask the system's contractor to install an audio and video alarm to alert operators at the centre when a message for upgrading a fire is received, Chan said. Chiu Sin-chung, chairman of the Fire Services Department Staff's General Association, said the findings were very surprising and called the error unacceptable. He said his fellow firefighters were furious with the mistake and would demand a full explanation from the department after Yeung's funeral next week. 'We fought for our lives to overcome the blaze but then our support came 18 minutes late due to human error,' he said. 'I cannot imagine how it upsets the family [of Yeung] at this moment.' Lawmaker James To Kun-sun, vice-chairman of the Legislative Council security panel, urged the department to review the operation of the communication centre. 'The control centre must offer imminent and accurate support to frontline colleagues,' he said. A veteran firefighter said the officer in the control centre was performing other duties at the time of the blaze, which then led to the mistake. But he said the delay might not be directly linked to the death because firefighters at the scene were usually unaware of the fire's number and only acted according to the situation. The building, in use since 1961, is one of 650 industrial buildings built before 1973 that mostly lack sprinkler systems. The department will launch a fire safety survey on 2,000 industrial buildings on Monday. It is to be completed in two months. How the blaze unfolded on March 8 8.19am Fire breaks out on fifth floor of Lai Cheong Factory Building in Cheung Sha Wan. 9.32am A text message requesting an upgrade to a No3 alarm fire is sent to the communication centre from the command post at the scene but an operator deletes it. 9.50am Fire Services Department upgrades the blaze to No3 after no reinforcements arrive and a frontline commander checks with the communication centre. 10.25am Four teams with breathing apparatus are sent into the blazing unit. 10.45am Senior fireman Yeung Chun-kit reported missing. 10.58am Blaze upgraded to No4 fire. 12.10pm Yeung found trapped under rubble. 12.55pm Yeung rushed to Princess Margaret Hospital, where he is declared dead. 2.24pm Blaze extinguished.