In brief
- Planes are designed and engineered to deal with high-speed winds you’ll find in the jet stream
- It’s safe for planes to fly with, against and across the jet stream – but pilots and flight planners will try and find you the smoothest air to fly in
- High winds at altitude can be forecast, measured and managed, meaning plans will be made to deal with them
High winds are no problem for modern planes
Planes are engineered to deal with the high-speed winds at altitude inside and around the jet stream.
In fact, pilots and flight planners often use these high-speed winds to increase speed, helping you to get to your destination earlier. Flying into a headwind can slow an aircraft and increase fuel burn, so pilots and planners will avoid it.
Wind isn’t a problem for planes. They’re engineered to fly safely inside the jet stream and fly across it.
The only time high winds can cause a problem is when the air speed changes rapidly, causing wind shear that can create turbulence. Thankfully, planes are built to withstand turbulence far more than that you – and any pilot – is likely to ever experience.
We’re going to explore the reasons why you can have complete faith in modern planes. We’ll look at load testing, structural elasticity and flight data monitoring.
Ultimate Load Testing (The 150% Rule)
Planes are tested by engineers and manufacturers to understand how they will perform in high winds. These tests provide reassurance to regulators that planes are more than tough enough to deal with jet stream winds.
Regulators require planes to meet an “Ultimate Load” standard. Engineers must bend the wings to 150% of the maximum aerodynamic force the plane could ever possibly encounter in the worst storm on Earth.
You can see examples of the tests that wings are put through here:
Before any commercial airliner – like a Boeing 737 or Airbus A320 – is certified to carry passengers, the manufacturer builds a full-scale prototype and intentionally tries to destroy it.
You’ll see through the videos above that wings are designed to flex like giant springs to absorb energy, acting as the plane’s shock absorbers.
These forces are far greater than a 100-knot jet stream wind. Plane wings are engineering to deal with the highest speed winds you can imagine!
Plane design and manufacture: Why micro-structural elasticity = strength
Modern airliners are built out of advanced aluminium alloys and carbon-fibre composites. These materials are deliberately engineered to be flexible (or, in engineering terms, elastic).
During high winds, the plane changes shape. The airframe expands, contracts, and twists to distribute stress evenly across the airframe.
These small movements enable the plane to manage the weather conditions without stressing the airframe or endangering the passengers.
When a plane passes through high winds, the metal doesn’t try to resist the wind. Instead, it yields and springs back. It might seem strange, but this small amount of bending ensures that planes doesn’t break, even during the strongest winds.
High upper-level winds don’t mean bumpy landings
At cruising altitude, a 100-knot wind is normal and means nothing to the plane. If a plane were to attempt to land in these conditions, it would be dangerous – but regulations exist to ensure this would never happen.
If you find yourself looking at a high-level wind chart (something best left to the experts) you need to separate upper-altitude winds from surface winds.
At the surface friction from hills, trees, and buildings slows the wind down drastically. In some cases, the jet stream may be 150 knots or more at altitude, but the conditions on the ground may be completely calm.
If there is a strong wind, planes may not land. Every aircraft has a maximum demonstrated crosswind landing limit (around 30 to 38 knots) of direct, sideways wind at the runway level that they’re allowed to operate in.
If the wind is too strong, the plane won’t land but will be diverted to another airport.
If the pilot is given clearance to land in high winds, they’ll often use a crabbing technique. It can look dramatic, but is an accepted part of flight, and planes are engineered to deal with it.
During such a landing, the landing gear undergoes extreme lateral (sideways) load testing. The main gear struts are massive hydraulic cylinders forged from ultra-high-strength steel.
They are designed to safely absorb the sideways momentum of a 70-ton aircraft tracking sideways onto a runway without warping, bending or breaking.
Airline enthusiasts love taking pictures of crab landings. They may look extreme, but remember, every plane in these videos landed safely.
Eyes in the sky: Continuous Flight Data Monitoring (FDM)
Planes – and the pilots who fly them and the flight planners who deal with route decisions – are connected by data.
There are hundreds of structural sensors in each plane monitoring the G-forces and stress loads acting on the airframe. They can also take information from other pilots (through PIREPs). Jet stream forecasting is highly accurate, enabling pilots to understand the movements of the jet stream, and things like wind shear, before they ever take off.
This monitoring works to measure turbulence. If a plane experience turbulence that approaches an inspection threshold (typically moderate-severe and severe turbulence), an automated alert is triggered.
The plane is grounded immediately upon landing for an engineering team to inspect it with ultrasound and X-ray equipment before it is ever allowed to fly again.
Remember, these incidents are incredibly rare, but there’s a plan in place to deal with it if it does happen.
Don’t be afraid of high winds – or fixate on wind charts
Planes are built to withstand the high winds at cruising altitudes, so there’s no need to be afraid. Smart engineering, advanced materials and strict regulations mean you can have complete faith in the strength and safety of a commercial plane.
Try not to fixate on upper winds and avoid checking turbulence forecasts. Instead, have confidence that the flight crew in the plane will do everything they can to ensure you have a smooth ride.
You can learn more about the science of flight, how planes fly and why losing an engine doesn’t mean your plane will crash in our Fear of flying section.
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FAQs
Planes can safely fly against the jet stream, but high winds can slow planes down which means burning more fuel. Instead of flying straight into a jet stream, pilots and flight planners will look for a smoother altitude with lower headwinds. (This could be above or below the jet stream.)
Yes, planes fly through Jetstream winds thousands of times every day, completely safely. Planes can safely fly with the jetstream, against it and across it. In fact, a plane to the USA from London may cross the jet stream several times on its journey.
Yes, planes cross the jet stream when travelling north to south (or the other way around). Crossing the jet stream may sound turbulent, but the wind is continuous, meaning it poses no problem to the plane.
What pilots are concerned with is wind shear. Wind shear is the rapid changing of wind speed and direction over a short distance that can create turbulence. While turbulence forecasting is far from foolproof, pilots and flight planners have access to advanced forecasting tools that they can use to plot a course and altitude that avoids the worst weather.
The jet stream isn’t continuous. It ebbs and flows and increases and decreases in intensity. During winter in the northern hemisphere the jet stream is often located across Europe and it can be intense. In the summer, it’s more likely to be found north of the UK and much weaker.
You can access jet stream forecasts online, but these are designed for professionals. Attempting to forecast turbulence from the jet stream alone isn’t a great idea. It’s best left to the professionals in the cockpit.
