Tiger Airways Australia had breached its air operator's certificate before the country's safety regulator issued a show cause notice (SCN) to the airline in March, said the Civil Aviation Safety Authority (CASA).
Subsequent incidents, including two breaches of flying below the minimum safe altitudes, led to CASA grounding Tiger from 2 July. Last Thursday, CASA sought an extension to the grounding until 1 August to allow it more time to complete its investigation.
The 30-page SCN that CASA issued on 23 March charged that Tiger "on a number of occasions" broke provisions of the Civil Aviation Act, Civil Aviation Regulations 1988 and Civil Aviation Orders, according to CASA's response to a freedom of information request.
CASA on 12 July rejected an April request to see the SCN in full, saying the contents could "cause damage to Tiger Airways' reputation".
"The allegations made in the SCN and the responses by Tiger concerning them would, or at least could reasonably be expected to, cause damage to Tiger Airway's reputation - which may lead to damage to its business, commercial and financial interests," CASA said.
CASA and Tiger have so far only said the SCN covers areas including oversight of maintenance and pilot training. Neither has disclosed the specific events that caused Tiger to breach its AOC.
Tiger disputed the SCN's allegations, CASA said. The carrier submitted an initial response and then a further response on 13 April totalling 42 pages which "makes submission as to why contraventions were not committed".
However, former Tiger managing director Crawford Rix disclosed at a May senate inquiry that the carrier restructured its operations department and increased the number of local maintenance management personnel at its Melbourne base. Such roles were previously located at the global headquarters of Tiger Holdings in Singapore.
"Where CASA has made suggestions in relation to improving processes and oversight, Tiger has taken immediate action and responded proactively with additional resource," Rix said at the inquiry, according to a transcript. Last week, Tiger announced Rix will resign by the end of the month.
No official determination about the breaches was made in the SCN and Tiger's responses. CASA said it was thus not in the public interest to release information that contained "no formal or final findings or conclusions about alleged contraventions or operational practices".
Privacy and defamation were also given as reasons for declining to release the documents. CASA said the SCN and Tiger's response named specific individuals alleged to have broken regulations, although neither CASA nor a court made formal findings concerning the individuals.
CASA declined to redact names as "some or all of those persons may be able to be identified by virtue of the factual matters raised in the notice".
At the senate inquiry, Senator Nick Xenophon told Tiger management that "a show cause notice may indicate a lack of satisfactory progress in terms of that dialogue between the regulator and the airline".
Rix replied: "I think the dialogue in general has been okay."
Tiger Holdings chief executive Tony Davis, who has since taken over Rix's role, then said the dialogue "has been very good", according to the transcript.