The Senate committee investigating the performance of Airservices Australia will recommence next week with the first public hearing since September 2015.
Airservices chairman Air Chief Marshal Sir Angus Houston is due to face the committee in Canberra on Wednesday 9 August.
The committee, chaired by Senator Barry O'Sullivan, held its first public hearing in November 2014, but had not completed its work by the time parliament was dissolved in May 2016, causing the inquiry to lapse.
In June this year, the Senate referred the inquiry back to the Rural and Regional Affairs and Transport Legislation Committee.
Over the 20 months since the inquiry opened, only three other public hearings have been held, dealing with several issues including the OneSKY air traffic management system, the introduction of ADS-B and the failure to fully implement the National Airspace System (NAS).
At this stage there is no indication if public submissions will be re-opened.