Economy airline Flyglobespan is to be prosecuted after claims it breached strict safety rules.
The Edinburgh-based firm is accused of allowing a flight from Liverpool to New York to take off when engine sensors were not working.
The decision to prosecute was made by the Civil Aviation Authority (CAA).
Flyglobespan denied safety breaches but said two senior managers had been replaced and that improved reporting systems had now been introduced.
The CAA is about to issue a summons against Flyglobespan for alleged breaches of the Air Navigation Order, the regulations which govern commercial flights.
It is alleged one of the company’s passenger planes flew from Liverpool to New York, even though engine pressure gauges were unserviceable.
It is also claimed staff then failed to file a safety report about the incident.
A Flyglobespan spokesman said: “As a matter of routine we have had, and continue to be involved in, normal regulatory dialogue with the CAA. However, there are some outstanding matters from last year and we have been informed that the CAA will issue us with a court summons.
“However, we categorically deny that we have been accused of ‘endangering passenger safety’ as claimed. The CAA has told us that the alleged offences are lesser technical matters.”
He said the firm could not comment in detail, but would vigorously contest any allegations deemed to be unjustified.
“The airline confirms that two senior managers have been replaced since last year and that improved reporting procedures have been introduced, and insists that passenger safety is never compromised,” he added.
Last autumn, Flyglobespan’s license to fly some transatlantic routes was suspended because of serious concerns about its operations.
The airline mainly flies from Scotland, including from Glasgow, Aberdeen, and Edinburgh airports, and from northern England, including Durham and Newcastle.
North American destinations include Calgary, Toronto, Boston and New York.