The 55-year-old first joined the Scottish Premiership club in 2013 as part of Derek McInnes’ management team and went on to spend eight years at Pittodrie.
He was also McInnes’ number two with Kilmarnock before spells as manager with Dundee and Ross County but was sacked by the latter in December with his side bottom of the Championship.
“Tony has a wealth of experience and knows the club inside out,” Pfannenstiel told his club website.
“He has excellent knowledge of the Scottish Premiership, both as a coach and a manager, and that will be invaluable for us in the short term.
“Our managerial search is now reaching its conclusion and we hope to be in a position to announce our new head coach imminently.”
Leven, who is in his third spell as caretaker and whose side sit seventh in Scotland’s top flight, is “delighted” with Docherty’s appointment.
“Obviously we were a bit stretched in that department,” he said. “He’s been at the club before, so it’s great to get Tony in with his experience.
“I spoke to him last night and he was buzzing. He says he was so excited he didn’t sleep last night. He is someone I can lean on and bounce ideas off and he’ll definitely help the team.”
Horneland left Saint-Etienne at the start of February with his side sitting fourth in France’s second tier.
Should Aberdeen decide to wait until the summer for the Norwegian to take charge, it will mirror the six-month delay in Thelin arriving at Pittodrie from Elfsborg in summer 2024.
