Thomas Hirschmann, Jet Aviation president and CEO and son of founder Carl Hirschmann Sr., has resigned from the family-owned business “to pursue other interests” and will henceforth have “no involvement in decision-making” at the company, a Jet Aviation spokesman told AIN late last month. The younger Hirschmann, 48, has spent his entire 29-year career with the company and had led the worldwide, operationally diverse business aviation conglomerate since 1990, five years before his father’s death.

Hirschmann has been replaced by veteran Jet Aviation executive Heinz Köhli as interim CEO. However, the spokesman told AIN there is no search under way for a permanent CEO. Köhli, a protégé of Carl Hirschmann Sr., joined the company in 1977, 10 years after its founding, and is highly regarded both inside and outside the company. His appointment promises to act as a stabilizing influence at a time of considerable upheaval.

The change is the latest twist in a whirlwind of management turmoil at the closely held, family-owned company. As evidence of how contentious the situation had become, Thomas Hirschmann’s name was not mentioned in the press release announcing the change. It simply stated that Köhli had assumed the title.

In late January, Jet Aviation parent company Hirschmann Industrial Holding’s board of directors ended months of speculation by declaring that it had decided not to sell Jet Aviation. The company had been on the market for about a year, represented by financial house Goldman Sachs acting as the bidding administrator. Identified prospects included General Dynamics/Gulfstream; Dassault; Saudi entrepreneur Prince Alwaleed Bin Talal Bin Abdulaziz Al Saud; UK finance house 3i; and European finance house Permira. Also widely reported to have been circling the target was financier (and NetJets owner) Warren Buffett, but he later said he never bid on Jet Aviation. At least 40 bidders received the prospectus, but none of the bids met with Hirschmann family approval.

President and CEO was Thomas Hirschmann’s most recent title at West Palm Beach, Fla.-based Jet Aviation. He had held the title of chairman and CEO of Jet Aviation’s privately held parent company–Zug, Switzerland-based Hirschmann Industrial Holding Ltd.–until April, when he resigned from that position but retained control of Jet Aviation. The aviation division is Hirschmann Holding’s largest element by far. With extensive worldwide interests in charter/management, completions and FBOs, Jet Aviation is widely regarded as the most diversified business aviation entity in the world and one of the most successful.

The shakeup at both Hirschmann Holding and Jet Aviation goes well beyond Thomas’ leaving. As part of the shakeup, his mother, Rita Hirschmann–widow of Carl Hirschmann Sr.–took over as chairman of the parent company from Moritz Suter, who succeeded her son as chairman only six weeks before on April 11. Suter, who at press time retained his position as a board member, came to Hirschmann Holding as a stabilizing influence in April from his post as the highly respected founder and chairman at Swiss regional airline Crossair. At that time, matriarch Rita Hirschmann was designated as “honorary chairperson” of the Hirschmann Holding board of directors when Thomas resigned as chairman and Suter was appointed. Further, Jet Aviation’s new CEO, Köhli, is one of three Hirschmann Holding board members who resigned on April 11, though he retained his position with Jet Aviation at that time. Köhli is the highest-ranking non-family Jet Aviation executive.

Rounding out the top management changes, Theo Staub, another long-time Jet Aviation executive, has been promoted to president and COO of the company’s U.S. operations. He had previously held that position on an interim basis, following the departure of Terry Kelley earlier this year.

Before taking on his current role, Köhli had been president and COO of Jet Aviation’s Europe, Mideast and Far East operation since 1991. Before that he headed the company’s aircraft management and charter arm. He was succeeded in that role by Staub in 1992. The spokesman said that even with the changes in the management structure, it’s not likely Jet Aviation would be broken up and sold piecemeal–a possibility some observers expected when the company was on the market last year.