The credit cycle for banks is not so much turning, as twisting, with industry-wide data showing an improving trend in the level of impaired assets as well as a persistent worsening in the level of overdue loans.Australian Prudential Regulation Authority data for the March 2011 quarter, published yesterday, shows the level of past due loans as a percentage of total assets has increased five basis points to 0.53 per cent. The absolute level of past-due loans stands at A$14.5 billion.This measure recorded a cyclical low, in early 2004, of 0.17 per cent and this has progressed upwards, by a few basis points, each quarter since then.APRA records the percentage of the banks' loans classified as impaired at March 2011 as being 1.11 per cent, a decline of five basis points over the quarter and down from the worst level (since the financial crisis) of 1.25 per cent in March 2010.The level of impaired assets at March was $30.1 billion, down $3 billion from the peak in the June 2010 quarter.The flow of new impaired loans is abating, but only slowly, with $5.1 billion recorded in the quarter.APRA put write-offs for the quarter at $2.2 billion, still higher than for any quarter in 2008, the year the credit cycle turned bad for banks.