The "critical facts" John Holland Group relied on to sack an OHS advisor for "misrepresenting" a safety incident have failed to stand up in the Fair Work Commission.

Commissioner Bruce Williams said the "difficulty" in the case "is that some of the critical facts on which the employer relied when making its decision to dismiss the [health, safety and environment] advisor have not been proven at this hearing".

He accepted that the advisor had provided an "accurate" report of the incident, in which a two-kilogram section of metal "unistrut" fell six floors to the basement in part of the Perth Children's Hospital Project.

John Holland sacked the advisor for allegedly "misrepresenting" the incident.

It claimed that when he prepared his report on the incident, he omitted information provided by workers he interviewed and "downgraded the severity" of the event.

This meant it wasn't reported to authorities, John Holland claimed.

The company's health, safety and environment manager on the project formed a view that the report didn't accurately reflect the facts of the incident and added some details to the report indicating that there were workers directly "in the line of fire" of the falling object.

Commissioner Williams said that when the HSE manager sought feedback on the changes from the advisor, he "misunderstood" the advisor's response as indicating the report should say there was no-one below, but "this was not what the [advisor] was saying at all".

The HSE manager then gathered written statements from the two key workers interviewed for the initial report, including one who claimed he had told the advisor that when he heard a "bang" he pulled his arms in quickly and the piece of unistrut "missed him by inches and was only a split second from hitting him".

The same worker claimed that the report failed to mention the information he provided to the advisor that there were workers in the basement at the time of the incident.

In his written response to the allegations that he misrepresented the facts, the advisor told the company that he had no recollection of the workers telling him people were in the basement, and in the FWC hearing in Perth on March 30 this year he denied being told by the worker that the unistrut had almost hit him.

Commissioner Williams said he had "no reason to disbelieve" the evidence the advisor gave on oath and noted that the Commission's role was to "determine whether particular conduct occurred based on the evidence presented at the time".

He said the advisor's legal representative had no opportunity to cross-examine the two workers who provided the statements to John Holland that directly contradicted his evidence.

The advisor didn't seek reinstatement and Commissioner Williams ordered the company to pay him 2.28 months' pay in compensation.

He substantially discounted the compensation because the advisor chose not to seek further employment after losing a new job "almost as soon as it started", when his employer found out the circumstances of his dismissal from the John Holland role.

Commissioner Williams said that after that experience, the advisor "consciously chose not to seek employment" because the he felt the dismissal had "tarnished his professional standing in the industry".

But Commissioner Williams said there was "no reason why the [advisor] could not have pursued other employment" outside his area of professional experience.

Leeder v John Holland Group Pty Ltd [2015] FWC 3118 (11 May 2015)