The head of the Transportation Safety Board says Canadian investigators have left Turkey for Iran to probe the downing of a Ukraine International Airlines plane last week.
TSB investigators are seeking access to the plane's flight data recorders, known as the ``black boxes,'' to help with the work being led by Iran's civil aviation authority.
The chair of the Canadian investigation body says Iran has been exceeding international requirements for such investigations.
Kathy Fox says she expects Canadian investigators will have access to the crash site outside Tehran and to the remains of the plane, which are being reconstructed elsewhere.
She calls Iran's level of co-operation encouraging.
Iran admitted over the weekend that one of its own missiles took down the Boeing 737-800, but called it a horrible mistake.