Family members of the American tourists killed in a fiery plane crash are believed to be making their way to Melbourne, a friend of the victims says.
Pilot Max Quartermain was flying US friends Greg Reynolds De Haven, Russell Munsch, John Washburn and Glenn Garland to Tasmania's King Island to play golf when their plane crashed into Essendon DFO on Tuesday, killing all five.
The victims' wives were in Melbourne at the time.
Bruce Mills, the vice president of a close-knit Texan golfing community in which Mr De Haven, Mr Munsch and Mr Washburn lived, said family members were on their way to Melbourne to provide support.
"Can you imagine the shock of getting that news?" Mr Mills told AAP.
The wife of pilot Max Quartermain was also "really struggling", her sister Irene Gould said.
Australian Transport Safety Bureau are investigating the crash and expect to hand down an interim report within 28 days.
They have already spoken with more than 100 witnesses but want to hear from anyone else who saw or filmed the crash.
They want to know, among other things, if the undercarriage was retracted or down.
Mr Quartermain made two mayday calls but they did not contain information about the cause of the crash, the worst in Victoria in 30 years.
