Mahmoud "Mick" Hawi, the former leader of the Comanchero outlaw bikie gang jailed for 21 years over the murder of Hells of Angels associate Anthony Zervas at Sydney airport, has been granted a retrial.

Zervas was killed in brawl in the domestic terminal airport departures hall in 2009.

During the fight, which broke out in in front of terrified passengers, Zervas - the brother of a Hells Angels bikie - was hit with a metal bollard and stabbed several times.

Hawi was convicted of the murder after a nine-month trial, but the NSW court of criminal appeal overturned the murder conviction on a number of grounds.

One of three judges ruling on the appeal, Chief Justice Tom Bathurst, said he could not be satisfied beyond reasonable doubt that Hawi "inflicted fatal blows to the head of Mr Zervas using a bollard" and that "it was not open for Mr Hawi to be convicted on that basis".

The three-judge appeal panel was not unanimous in its decision.

Chief Justice Bathurst noted that his preference was to allow the appeal and acquit Hawi but indicated that Justice Lucy McCallum wanted the appeal dismissed.

The third judge on the panel, Justice Derek Price, preferred the option of a retrial.

Hawi was originally given a maximum sentence of 28 years.

In appealing against his conviction his lawyers argued it was a miscarriage of justice.

His retrial will be set for a date that is yet to be determined.