In 2017, at Princess Juliana International Airport, a New Zealand tourist was holding onto a fence when the force of jet engines blew her backward, causing serious injury. She was taken to the hospital but later died.
Jet blast is the strong air pushed out from the back of jet engines. This fast and hot air moves the airplane forward by creating thrust. While it's important for flying, jet blast can be very dangerous on the ground because of its powerful force.
Sometimes jet blast creates high pressure that pushes objects, vehicles and people. In other cases, the high velocity causes the air pressure to decrease, which can throw objects or even lift the pavement into the air.
This phenomena of high-speed air and low pressure zones is better explained by the Bernoulli experiment.
It uses a sheet of paper, where you blow air over the top of the paper, the speed of the air increases. According to Bernoulli's principle, as the speed of the fluid (air in this case) increases, the pressure exerted by the fluid decreases.
Pressure Difference: The faster-moving air over the top of the paper creates a region of lower pressure compared to the still air beneath the paper. This pressure difference generates a lift force, causing paper to rise.
This low-pressure zone creates erosion and damage to the apron surface, especially in areas where the blast is directed towards the ground.
Jet blast can be a significant factor in creating Foreign Object Debris (FOD) on apron surfaces. FOD refers to any loose object that can pose a threat to aircraft safety, such as stones, debris, and litter. The high-velocity air from jet blasts can displace and scatter these objects, making them hazardous.
This happened at Sialkot International Airport when a Boeing 737-400 did a High-Power Engine Runup, the pavers/interlocking bricks at the Apron got off from the ground and hit the plane extremely hard putting swear damages to the Plane Shell.
This curious case is an example of low pressure by the Bernoulli effect that take the bricks to fly, it maybe sounds curious, but it is a case of bricks flying by aerodynamic forces
Another example, happen on the Halfpenny Green Airport near Wolverhampton, Uk on April 30 2017. This was also a mis bonding of the asphalt or layer separation that then by the jet blast and the Bernoulli effect become blow up.
find a video on: https://www.bbc.com/news/av/uk-england-birmingham-39778809
An additional case, Navegantes Airport in Santa Catarina, Brazil by a Boeing 737 from Gol airlines prepared to take off, the sheer force of the jet blast caused significant damage to the asphalt at the end of the runway.
Find a link to the video on:
Practical Implications
In practical terms, this means that the jet blast can cause significant effects on the ground and nearby objects:
Erosion: Just as the air stream can pull a piece of paper to flow over, the jet blast can tear asphalt and then cause damage to the airplane itself.
Safety Concerns: Understanding how jet blast flows over and around surfaces helps in designing safety zones and protective measures at airports.
Infrastructure Impact: As the jet blast follows the ground profile, it can create high and low-pressure zones behind the jet turbines. This condition can cause the jet blast to cause damages to vehicles and staff even at distances up to 600 meters at takeoff power.
Obstacles and Structures: When the jet blast encounters obstacles like buildings, hills, or other structures, the powerful effect can cause the air to wrap around these obstacles, potentially causing unexpected and turbulent airflows, even behind these obstacles.
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