A Boeing 747 cargo jet unbelievably reached high supersonic speeds during a descent
Published on Jan 23, 2026 at 5:02 PM (UTC+4)
by Ben Thompson
Last updated on Jan 23, 2026 at 5:02 PM (UTC+4)
Edited by
Mason Jones
A Boeing 747 cargo jet once reached high supersonic speeds during a descent in a remarkable display of power.
Not that it intended to, mind you.
This happened back in 1991 when reports circulated that the aircraft had allegedly reached speeds of Mach 1.25 while descending.
Admittedly, it was apparently down to a malfunction, but it’s still impressive.
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How a Boeing 747 cargo jet reached supersonic speeds
If you’re old enough to remember, you may be able to recall some newsworthy events from December 1991.
Hulk Hogan had become a 4-time WWF champion, the Soviet Union was formally dissolved, and Michael Jackson was sweeping up awards at the Billboard Music Awards.
But in the world of aviation, there was a remarkable milestone that may have otherwise gone unnoticed.
On December 12, a Boeing 747 cargo jet inadvertently went supersonic while descending.
The plane in question was an Evergreen International Airlines Boeing 747-100F, recently converted into a freighter jet.
It was flying from JFK Airport in New York all the way to Tokyo, stopping off at Anchorage International Airport in Alaska.
As they were coming into Anchorage, the crew noticed a failure warning on the inertial navigation system (INS).
Cruising at 31,000 feet over Canada, the crew noticed an alarming development – the plane had gone 90 degrees to the right and was descending at an angle as steep as 30 to 35 degrees.
This caused a rapid acceleration and fell over 10,000 feet before the pilots could get the plane back under control.
It stabilized at 22,500 feet, and had to be landed in Duluth, Minnesota.
Fortunately, nobody was injured in the chaos.
During this descent, the plane exceeded the maximum speed limit of Mach 0.92 and reached Mach 0.98.
However, some reports have even indicated that the plane reached speeds of Mach 1.25, which would put it beyond the supersonic limit.
Speeds of more than 0.92 has not been confirmed by the National Transportation Safety Board, but Boeing released this statement to The Chicago Tribune back in 1992.
“Original flight tests of 747s conducted in 1969 and 1970 took 747-100 models to speeds of Mach 0.99. In addition, Boeing knows one case in which a 747 operated by Evergreen International made an emergency descent at speeds that exceeded Mach 1,” a spokesperson said.
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Which planes do we often associate with supersonic speeds?
If you were to ask the average person on the street about supersonic jets, chances are they’ll mention Concorde.
Yes, that beloved plane from a bygone era – it flew so fast that passengers could see the sun rising on an evening flight, and it had one massive boom.
Even down to its very last flight, the Concorde was iconic.
There’s no question about it – this plane is dearly missed by aviation fans the world over.
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Following stints at LadBible, The Sun, The New York Post, and the Daily Mail, Ben joined the team full-time in February 2025. In his role as Senior Content Writer, his sparkling copy, the ability to sniff out a good story at 100 paces, and a GSOH quickly led to him becoming an integral and invaluable member of the writing staff.
