A sonic roar rung over the German city of Stuttgart on Saturday evening, as the Bundeswehr deployed two fighter planes to intercept a Korean Air passenger plane when radio contact cut out.

The passenger aircraft was eventually escorted by the jets to Stuttgart airport where it made an emergency landing.

Read more: Report: German jets useless at night

The Boeing aircraft was travelling from Seoul to Zurich and remained grounded overnight as engineers inspected it for technical issues. On Sunday it was revealed that the plane's radio transmitter did indeed have a fault.

The 211 travelers on board the Korean Air flight stayed in the airport overnight due to a late-night flight curfew, blocking outbound flights after 11 p.m. On Sunday, they took the final leg of their journey to Zurich by bus, a drive that usually takes around two hours.

The live air flight tracker Flightradar24 highlighted the enormous U-turn the Korean Air flight performed to land in Stuttgart.

It was the second such incident in as many days. On Friday, two Bundeswehr jets followed an Egyptian passenger plane from Hurghada, which had lost contact with air traffic control over the border region between the German states of Hesse and Bavaria. Fortunately, it was not required to make an emergency landing after it eventually regained radio contact. It landed soon after at its destination in the German city of Münster.

A spokesman for the German air force said the most likely reason for the airliner losing contact was that the pilot had simply input the wrong radio frequency.

Jet deployment causes a scare on the ground

In both instances, the Bundeswehr jets reportedly took off so quickly that the sonic roar could be heard over a radius of around 100 kilometers (62 miles), frightening locals and prompting them to think the worst.

On Saturday, police in the city of Reutlingen, some 40 kilometers from Stuttgart, said they had received 250 reports of an explosion. Police in northern Bavaria said they had received similar emergency calls on Friday.