Passengers recently bought tickets on Tiger Airways flights for up to three weeks unaware that CASA had refused to allow it to expand its small fleet of jets in Australia until it responded to a show cause notice that could have led to it being grounded.

While Tiger has since provided CASA with responses that it is reviewing, the very travellers the Australian safety regulator is supposed to protect by enforcing the rules were left in the dark as to its concerns.

It must be emphasised that Tiger is at no risk of being grounded after it lodged detailed answers to all of the queries raised by CASA when it served the notice on the Singapore Airlines controlled low cost carrier on March 23.

That notice gave Tiger 21 days to respond to CASA concerns about its pilot training and checking standards and a range of safety related processes in its operations.

CASA is now reviewing what is said to be a substantial set of submissions from the carrier, and Tiger said this morning it did not believe its licence to fly in Australia was at risk.

Crikey understands CASA took the quite serious step of serving Tiger a show cause notice because of information provided to the Senate Inquiry into pilot training and airline safety standards, which is due to report by May 4.

However, CASA has confirmed that while it refuses to disclose the matters it raised in its show cause notice, they did not constitute an immediate threat to safety and require it to exercise its powers to ground Tiger or place restrictions on its air operator certificate.

Tiger did not confront CASA with anything as serious as the issues it faced with Ansett before Easter 2001 when the regulator held real fears of that the neglect of Ansett’s safety obligations would lead to a crash.

At that time CASA used its risk-to-public-safety mandate to ground Ansett’s  fleet of aged Boeing 767-200s and more broadly threatened to suspend its AOC  after discovering the carrier had neglected to carry out a range of compulsory inspections, had not keep correct records, and had flown one of the 767s in passenger services on multiple sectors with inoperative emergency evacuation slides.

However, the secrecy with which CASA dealt with Tiger is in contrast to the open and continual public disclosure policies of its US counterpart the FAA, in which the travellers are constantly advised of infringements of the rules by American carriers.

In general terms, CASA defends its policy on the grounds that it is engaging in a process not necessarily leading to a prosecution  when it raises issues with an airline, and is more concerned with the safety outcome. That said, a show cause notice on a mainline Australian airline is the last card CASA waves before sending the offending carrier off the field.

Under its previous CEO, Bruce Byron, CASA failed to tell the public that it knew the Aerotropical operation in far-northern Queensland was dangerous, and tolerated its continued operations as an airline until one of its flights crashed on approach to the Lockhart River airstrip in 2005, killing all 15 on board.

After that crash, when grilled by a different Senate inquiry,  Byron refused to accept that CASA had such a duty to communicate with the public.

His successor, John McCormick, showed a similar reluctance to air adverse internal reports on airlines at the most recent Senate hearings into airline safety matters, however it would not be surprising if under him CASA pursues further show cause notices against mainline Australian airlines.