Airline firm FlyGlobeSpan has pleaded guilty to two charges of breaching civil aviation rules after allowing a plane with instrument failure to fly.
The Edinburgh-based firm admitted allowing a flight from Liverpool to New York to take off when engine pressure sensors had failed.
Westminster Magistrates’ Court heard the crew had to manually adjust the throttle and use a handbook.
The company said there was never any risk to passengers.
The prosecution was brought by the Civil Aviation Authority (CAA), which told the court the crew on the previous flight to Liverpool had been informed about the problem.
Alison Slater, acting for the CAA, said the sensors that indicate the thrust of each engine had failed.
She said that by declaring the aircraft serviceable to fly later that day, on 28 June, the company had breached safety regulations which require at least one engine pressure indicator to be working for a plane to fly.
Stephen Spence, defending, said the sensors were not universally installed in all aircraft.
He said: “The workload increases, but it increases to what we would submit is an acceptable level and well within the capabilities of the pilot.”
He said the crew on board the flight from JFK to Liverpool had managed without incident or mishap to fly the plane for more than six hours after they discovered the fault, before landing successfully at Liverpool.
He said the clearance of the flight to return to New York had arisen because of a misinterpretation of the rules.
He stressed the airline had been under no commercial pressure to continue operating the flight, as there were only 20 passengers on board when it took off.
He added: “I stress that there was never at any stage any question in the minds of anybody of putting people in danger. Two offences arose out of one set of circumstances.”
District Judge Timothy Daber, said it was “clear” to him the plane had been capable of working safely and agreed there was no danger to passengers.
He also noted senior members of staff responsible for the breach had been removed.
But he said the sensor was “clearly there for a reason”, to enhance the safety of an aircraft.
He said there was a “heavy duty” on airline operators to ensure the minimum equipment list and breaches like this could not be tolerated.
“Therefore, any fine has to be commensurate with the considerable means of the defendant company in this case,” he said.
The case was referred to Southwark Crown Court for sentencing.