Rare weather event means commercial jets are flying faster than 'speed of sound'

02 November 2023 , 14:01

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An American Airlines flight reached 778mph this week (Image: NurPhoto via Getty Images)

A rare weather phenomenon is causing the first commercial jet to go faster than the speed of sound since Concorde last flew.

This week passenger planes are whizzing across from the US to the UK at record speeds. Some of them have hit 778mph, which is a full 27mph faster than sound travels in “sea level standard conditions,” according to NASA.

The planes are also going around 200mph faster than the normal cruising speeds of similar sized jets. Sadly the turbo-charged aircraft aren't going quite as fast as Concorde, the last super-sonic passenger jet to grace the skies and which stopped taking passengers 20 years ago last week. The triangular plane had a cruising speed of 1,304mph, or twice the speed of sound.

The speed of sound on the ground is different from the air, due to its varying thickness. When a plane is higher up, the sound barrier is broken at a lower speed. At 30,000 feet it drops down to 678mph, meaning the trans-Atlantic jets are far exceeding it.

Concorde made its last flight 20 years ago (Matt Cardy)

The reason for this week's speed boost is that the jet stream is currently incredibly strong.

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The jet stream is “core of strong winds around five to seven miles above the Earth’s surface, blowing from west to east,” as the UK’s Met Office explains. It is responsible for the shorter amount of time it takes to fly from the US to the UK rather than the other way round. Generally they take an hour less.

Right now the jet stream is very strong because of the difference in temperatures in the US compared to in Europe. CNN meteorologist Sara Tonks explained: “This week’s burst of cold air in the United States has upped the difference in temperature between the United States (cold!) and the Atlantic Ocean (warm!). This increase in the temperature gradient is amplifying the speed of the jet stream, which is driven by temperature differences.

“The jet stream is expected to help strengthen Storm Ciaran, a low pressure system and potential bomb cyclone that is expected to arrive in Europe tonight [Wednesday].”

Some passengers are enjoying the benefits of the speed boost. An American Airlines flight 106 from JFK to Heathrow arrived 54 minutes early on Wednesday morning. A Delta flight 186 got from Los Angeles to London half an hour early on November 1.

Knowing that there are supersonic planes whizzing passengers across the Atlantic may be some comfort for those who miss the heady, optimistic days of Concorde. The plane - one of the most iconic ever built - flew its last passengers 20 years ago last week. In the early hours of October 24, 2003, the supersonic jet that melted French and British hearts, Concorde, ferried its last load of passengers across the Atlantic ocean from New York JFK to London Heathrow.

Two other supersonic jets joined it as it flew across the west of England, forming an honorary guard for the famed plane before it touched a load of paying customers down for the final time, bringing an era to an end.

Milo Boyd