The embattled South African Civil Aviation Authority (CAA) suffered yet another blow on Tuesday with the resignation of its chief executive officer Zakes Myeza.

Myeza was touted as the saviour of the CAA when he took office in February last year, becoming the first permanent appointee to the post in years - at least since the debacle surrounding Trevor Abrahams.

Abrahams was chief executive and commissioner for civil aviation for five years, serving at least the last part of this under a cloud of unproven claims of fraud and corruption.

Nonetheless, the then Transport Minister Dullah Omar thanked Abrahams for his work when he bowed out in September 2003 when his contract as chief executive was not renewed.

Abrahams had indicated he was also unable to continue as commissioner.

He was placed on an indefinite compulsory leave of absence in December 2002 after accusations that he and Carole Fortuin ran a company which benefited from contracts with the CAA.

In February 2003, a disciplinary hearing reportedly found him guilty of charges relating to dishonesty, intimidation, defiance of the board mandate and favouritism.

Wrenelle Stander was appointed acting commissioner for civil aviation after Abrahams was arrested for alleged fraud, corruption, obstruction of justice and Civil Aviation Act contraventions in 2000 - charges which were never proved.

However it was Sakhile Nyoni who was appointed as acting chief executive in his stead in 2002. Abrahams stayed on as commissioner until September 2003.

Nyoni made way for Seboseso Machobane, who acted as chief executive from July 2003 and was appointed as commissioner for civil aviation from October 2003 until end of March 2004.

His shoes were filled by Mongezi India, who also acted as chief executive, in November 2004.

The CAA looked to Myeza as a "dynamic person" who would take the regulatory body "to a higher level" when it appointed him in March 2006.

His appointment "follows a string of unsuccessful recruitment endeavours to find a suitable candidate for this position," said CAA Board chairman Duke Moorosi.

Having just grounded one of the country's major carriers, Nationwide Airlines, news of Myeza's resignation on Tuesday came at a critical time for the CAA and was viewed as "suspect" - at least by the Democratic Alliance.

DA transport spokesperson Stuart Farrow said he had asked Transport Minister Jeff Radebe for a full explanation of the circumstances surrounding Myeza's "abrupt departure".

Myeza was credited with improving, among other things, the CAA's organisational capacity and processes, regulatory compliance, structural alignment, employee relations and morale.

"He is also widely credited with bringing about an environment conducive to aviation safety in South Africa," Farrow said in a letter to Radebe.

His sudden departure had raised the suspicion that the ending of his contract could be linked to the International Civil Aviation Organisation's finding that the independence of the CAA's Air Safety Investigations Department was lacking.

There were also suspicions that it was linked to the recent grounding of Nationwide, Farrow told Radebe.

However the CAA has dismissed the Nationwide link out of hand. His resignation had "nothing to do with" the Nationwide grounding, said CAA spokesperson Phindiwe Gwebu.

Announcing the resignation, Gwebu said Myeza was leaving to allow the CAA to unify the positions of chief executive officer and commissioner for civil aviation.

This was in line with the findings of two international audits of the country's civil aviation industry.

Myeza's resignation had been "reluctantly" accepted by the Board, Gwebu said in a statement posted on the CAA's website.

"The decision is regrettable and comes at a time when the industry has expressed its confidence in the leadership abilities of Mr Myeza," Gwebu said.

The CAA appreciated the "drastic and revolutionary changes" under his 20 months of leadership in "trying circumstances".

"The loss of his leadership and expertise... is regretted."

The CAA has yet to announce his replacement - who will also serve as commissioner for civil aviation.

At the moment, that job falls to acting commissioner Gawie Bestbier.

The commissioner manages and oversees the safety regulation of civil aviation in South Africa, adjudicates appeals against CAA regulatory decisions, and chairs statutory committees on airspace and aviation security matters.

Myeza had indicated that he planned to speak about his resignation, Gwebu said on Tuesday - but only when he came back from a lunch organised for him by his colleagues.

He has, among others, a BCom in accounting, income tax, commercial law and statistics, an MBA, a certificate in aviation management from the International Aviation Management Training Institute in Canada, and a certificate in corporate governance from the Rand Afrikaans University.

At the time of his appointment he had more than 15 years' experience in general business management, and was Johannesburg Development Agency's finance and support services executive director.

He held executive leadership roles in Petronet, the Airports Company South Africa, and Gtech South Africa.

He had also helped set up retail, property and ICT businesses and was a director of the Newtown Development Company and the Constitution Hill Development Company, and voluntarily served as a treasurer and trustee of the Johannesburg Trust for the Homeless. - Sapa