Chief Executive Donald Tsang Yam-kuen's popularity has fallen further after the government's delayed decision to send chartered flights to bring home Hongkongers stranded in Thailand early this month. The incident also led to a drop in the public's ratings for the government's ministerial, or accountability, system, a study by Chinese University found. The administration initially refused to send chartered flights to pick up residents stranded in Bangkok, but later made a U-turn after a couple from Hong Kong were involved in a traffic accident, in which the husband was killed. In the survey, conducted in mid-December, the chief executive was given 50.7 marks out of 100, down from 51.5 in November. The pass mark is 50. Mr Tsang's popularity began to fall in June, when he scored 59.2 marks, 6.4 down on the May figure. His rating has not risen since. Respondents gave the 'accountability system' 42.5 marks, down from 45.1 last month. This rating has been below the pass mark since July. Timothy Wong Ka-ying, associate director of the Hong Kong Institute of Asia-Pacific Studies at Chinese University, said: 'A further drop in the chief executive's popularity reflects people's anger after the chartered-flights incident.' He said the rating had been under pressure since June, followed by a number of perceived mistakes in the administration's policies. Unless there were further significant blunders from the administration, Professor Wong expected the chief executive's popularity rating to remain at about the same level in the coming months. More respondents in the latest survey said they were dissatisfied with the government's performance - up 7.4 percentage points from the 29.2 per cent recorded last month. The survey interviewed 856 people by telephone in mid-December. It had a margin of error of plus or minus 3.37 per cent and a confidence level of 95 per cent.