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Writer's pictureJuan Correa

Understanding Jet Blast: The Hidden Dangers on the Tarmac

In the early days of aviation. The pioneering efforts to fly higher, faster and with more passengers requires better engines, with more power.

 


Dornier Do X, 12 engines, 525 hp each. taken form: https://en.wikipedia.org/wiki/Dornier_Do_X


In those days, noise was not a concern, and the blast, well, the engines were not powerful enough to create a dangerous propeller blast.

 

But then the jet engine came to provide unimaginable amounts of power, now the giant airplanes with 4 to 6 and even 8 piston engines became part of history books, the new horizon belongs to the jet age.

 


Sud Aviation: Caravelle with around the same size of the Do X, with around 10 times more power. https://en.wikipedia.org/wiki/Sud_Aviation_Caravelle


Jet engines are much more powerful than piston engines, capable of much higher thrust, higher speeds and higher altitudes. This makes them suitable for commercial airliners, military aircraft and high-speed business jets.

 

Piston engines, while less powerful, are more efficient at lower speeds and altitudes, making them ideal for general aviation, training and agricultural applications.

 


Radial piston engine (@brice_cooper18) unsplash

That's why we see so many jets at airports these days. With their powerful engines, air travel has the capacity to change our world, but on the tarmac it can become dangerous. It's important to manage these conditions to keep vehicles, aircraft, buildings and people safe.


Jet engines can produce noise levels of 120 to 150 decibels, especially during takeoff and landing, but during ground operations an engine at idle or low power for takeoff can produce up to 90 dB, well above the safe exposure limits set by occupational health guidelines.


Prolonged exposure to noise levels above 85 decibels is known to contribute to noise-induced hearing loss (NIHL) among workers in high-noise environments such as under-wing activities.

Jet blast from aircraft engines also poses significant dangers to vehicles, personnel, and buildings at airports.


Here are the key risks associated with jet blast:

  1. Dangers to vehicles:

  • Jet blast can lift and propel heavy objects, including vehicles like baggage carts, lift trucks, and even smaller aircraft.

  • Unbraked vehicles may be shifted or moved by the powerful exhaust forces.

  • In extreme cases, jet blast can weathercock (turn) braked airplanes.

  1. Dangers to personnel:

  • Jet blast can cause bodily injury to airport staff and passengers.

  • People can be blown down or injured by the high-velocity exhaust.

  • Objects propelled by jet blast can strike and injure personnel.

  • Noise levels from jet engines can exceed safe exposure limits, potentially causing hearing damage.

  1. Dangers to buildings and structures:

  • Jet blast can flatten building structures and shatter windows.

  • It can uproot trees and damage other vegetation near taxiways and runways.

  • Unprotected areas exposed to continued jet blast can erode, releasing soil, stones, and debris (FOD) that may cause further damage or be ingested by engines.

  1. General hazards:

  • Hazard Area for Takeoff Thrust: For takeoff thrust, the hazard area can extend up to 1,900 feet behind the aircraft

  • Even at low power settings (35-40% N1), the jet blast "damage profile" can be significant.

  • Blast velocities greater than 48 km/h (30 mph) can cause loose objects to become airborne projectiles.



Demonstration of the power of the jet blast - Ground vehicles and light aircraft simply don't stand a chance.


Turbine technology has advanced since the beginning of the jet age, with modern materials, less fuel consumption and less noise. But the jet blast deflectors and noise fences are almost the same as they were several decades ago, that's why airport separation distances and ground operations remain frozen with no advances in noise mitigation, clearance and procedures.


Just take a look at the old pictures of airports from the sixties and seventies and the apron is just as it used to be, no changes.


Vintage Miami international airport image, the concourses with finger piers are the same arrangement and same operational procedures to avoid jet blast hazards. https://en.wikipedia.org/wiki/Miami_International_Airport

With the new challenges of airport capacity, environmental goals, and better occupational health and safety measures to keep ground personnel healthier.


With the new challenges of airport capacity, environmental goals, and better health and safety measures to keep ground personnel healthier, the opportunity has arisen to provide a new generation of jet blast deflectors.

 


Next-generation jet blast deflectors that reduce noise and control the jet blast, allowing maintenance personnel to work in an area with up to 30 dB less noise and no fumes or exhaust.


In another post, we will look at the solutions to create the next generation of airports in a safer, more sustainable and environmentally friendly aviation industry.

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