"He was slouched in the chair, legs open, and a head cover from a seat in his hand," Hand said.
He said when a second worker arrived Malka "used the headrest cover to cover up his penis. "He asked them to stop for a moment, then carried on."
Malka was also told to stop vaping as it could set off the smoke detectors.
"In summary he admitted his behaviour was out of character he had no recollection of the journey or staff," Hand said.
The 33-year-old tried to blame his actions on a sleep disorder and long working hours.
"He made reference to previous sexual activity with his girlfriend when he was asleep and thought the same must have happened," Hand said.
Malka changed his plea to guilty after an expert reported failed to confirm his actions were the result of a lack of sleep, according to The Argus.
He was ordered to do 100 hours' community work and may be sacked from the police force.
Malka's representative, Heather Oliver said he is an exemplary officer and is remorseful for his actions.
"He recognises this was a wholly unacceptable course of conduct.
"He's clearly not seeking an audience or a reaction. He's clearly in his own world.
"He is utterly humiliated, ashamed and embarrassed and he must take on the chin the loss of his good name."