A police search for a missing helicopter pilot at Lake Sumner in North Canterbury is expected to resume this week.
Michael Mehrtens, 35, crashed into Lake Sumner while spraying weed on 21 May.
The search was halted by police on 28 May so that information gathered by an underwater robot of the wreckage on the lake bed could be reviewed.
Canterbury police operations manager Inspector Craig McKay says a radio sonar device will be used this week to provide a more detailed picture of the debris and hopefully reveal the location of Mr Mehrtens' body.
Mr McKay says if the sonar is not able to locate the missing pilot, specialist lake bed surveying equipment may have to be brought in.
The search is scheduled to resume on Tuesday.