Flaps, Lift & Drag: The Secret to Smooth Landings
A student pilot is coming in for a landing, focused, and following the checklist. Everything seems under control — until another aircraft unexpectedly crosses the runway ahead. The instructor calls for a go-around. The student quickly pushes in full power, but in the rush of the moment, they make a critical mistake—they retract all the flaps at once.
At just 8 feet above the runway, the sudden loss of lift causes the aircraft to sink like a rock. The instructor reacts instantly, taking control and adding just enough back pressure to avoid a hard touchdown. It’s a close call, and the student is left wondering: What just happened?
This scenario is more common than you might think. Many student pilots don’t fully understand how flaps impact their aircraft’s performance. Whether it’s retracting them too fast in a go-around or dumping them all at once on the final approach, improper flap usage can lead to unsafe situations.
In this article, we’ll break down how flaps affect your landing point and approach angle, explain why changing flap settings too quickly can be dangerous and describe the best practices for using flaps during landings and go-arounds.
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What Are Flaps, and Why Do They Matter
Flaps are one of the most powerful yet often misunderstood tools at a pilot’s disposal. These hinged surfaces, located on the trailing edge of the wings, might not seem like much, but they play a critical role in landing, take-off, and overall aircraft control.
Here are a few ways how flaps may modify an aircraft's performance.
Flaps when deployed, let the aircraft to generate more lift at lower speeds.
Flaps also reduce stall speed, making it more difficult for the aircraft to stall.
While they enhance lift, flaps also increase drag, which slows the aircraft down.
During landing, flaps steepen the descent angle without increasing airspeed, allowing for a more controlled approach.
When retracted, both lift and drag return to normal, restoring the aircraft’s usual aerodynamic characteristics. But it also means that retracting flaps too quickly — especially at low speeds — can cause a sudden loss of lift, leading to an abrupt sink rate.
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How Do Flaps Work
Flaps fundamentally reshape airflow over the wing. By extending and altering the wing's chord line — an imaginary straight line from the leading edge to the trailing edge — flaps effectively modify the airfoil's shape. This modification gets the wing to generate significantly more lift at lower speeds.
Specifically, deploying flaps increases both the wing's effective surface area and its camber (curvature). The increased surface area provides more area for lift generation, while increased camber allows the wing to produce lift at a higher angle of attack.
Balancing Lift vs. Drag
So in simple words, using flaps gives you two distinct advantages in your plane:
You can produce more lift, giving you lower take-off and landing speeds.
You can produce more drag, allowing a steeper descent angle without increasing your airspeed on landing.
However, proper flap usage is essential. They must be deployed smoothly and incrementally to avoid sudden and potentially hazardous changes in the aircraft's handling. Think of flaps as a trade-off between extra lift and extra drag:
More lift → Allows the aircraft to fly slower without stalling
More drag → Slows the aircraft down and steepens the descent angle
Too much, too fast? → Sudden flap retraction removes both lift and drag instantly, causing an unexpected sink.
How Flaps Define Your Landing Point
Flaps directly influence where your aircraft touches down on the runway. When you are on the final approach without flaps — your descent path is shorter, and you’ll float further down the runway before touching down. Now, add flaps. The increased drag slows you down, and the extra lift helps keep you stable at lower speeds. This combination allows you to land closer to your intended touchdown point rather than overshooting.
Now let's imagine you suddenly retract flaps while low and slow — especially near the runway. You’ll instantly lose both lift and drag, causing an abrupt sink. That’s why flap adjustments should always be smooth and controlled to maintain a stable approach and precise landing.
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How Flaps Change Your Approach Angle
Flaps also help you shape your approach angle when you land. Without flaps, your approach tends to be flatter, requiring either a longer runway or more precise speed management to avoid floating past your intended landing point. But when you extend flaps, the extra drag slows you down, letting you descend at a steeper angle while maintaining control. This is especially useful when landing at shorter runways or obstacle-limited airports, where you need to clear terrain before making a precise touchdown.
However, misusing flaps can create problems. Deploying them too quickly can cause a sudden pitch-up, momentarily increasing altitude when you actually want to descend. Retracting them too quickly on a go-around can remove lift too fast, causing an unexpected sink. That’s why flap adjustments should always be smooth and deliberate.
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How Flaps Affect Pitch and Approach Control
Extending flaps doesn’t just influence lift and drag — it also has a noticeable impact on an aircraft’s pitch behaviour. This effect varies across different aircraft designs, but the fundamental principles remain the same.
The flaps have an angle between 35° and 40° when fully opened.
Flaps at 15° or less primarily increase lift with minimal drag. This extra lift can cause the aircraft to momentarily balloon upwards, but the nose-down pitching moment created by flap deflection generally counteracts this effect.
Flaps beyond 15° generate a significant increase in drag. In high-wing aircraft, this can introduce a noticeable nose-up pitching tendency due to changes in airflow over the horizontal stabiliser. If flaps are deployed without adjusting power or pitch, airspeed will drop, requiring either increased power or a lower pitch attitude to maintain a stable approach.
How to Adjust Approach Angle with Flaps
On the final approach, judging the descent angle correctly is key to landing precisely where intended. If the aircraft is on track to overshoot the landing point, deploying more flaps, reducing power, and lowering the nose will steepen the approach. Conversely, if the approach is too shallow and falling short, increasing power and slightly raising the nose will help adjust the descent angle.
One crucial rule: never retract flaps to correct an undershoot. Doing so suddenly reduces lift, which can cause an abrupt sink, making a controlled landing much harder. Instead, manage approach corrections smoothly with power and pitch adjustments, ensuring a stable and safe touchdown.
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No-Flap Landings
While flaps are crucial for most landings, certain situations call for no-flap or partial-flap landing. For instance, in strong, maximum crosswind conditions, keeping flaps retracted provides better positive control during turbulence. Similarly, when landing at a long runway, skipping flaps simplifies the approach. In busy airport environments, no-flap landings can also expedite the final approach, helping maintain traffic flow.
Without flaps, you can expect:
A shallower approach angle – Flaps increase drag and steepen descent, so without them, your aircraft will float more before touchdown.
A longer landing roll – Without the extra drag from flaps, you’ll need more runway to slow down.
A higher approach speed – Since flaps lower stall speed, landing without them means you’ll need a faster approach to maintain a safe margin above stall.
A different sight picture – The nose will likely be higher than usual during approach, which can be disorienting if you’re used to normal flap landings.
A no-flap landing requires finesse and planning, but with practice, you’ll develop the skills to handle one confidently — whether it’s by choice or necessity.
Master the art of crosswind landings with our comprehensive guide. Read more and become a more confident pilot Taming the Wind: Crosswind Landings Explained.
Airhead's Takeaway
Alright, let’s quickly recap the key points about flaps in just a few lines.
Extended flaps increase wing surface area, improving lift.
Flaps generate both lift and drag, impacting approach and landing.
They lower stall speed, making it harder to stall.
On landing, flaps increase drag, allowing for slower approach speeds and shorter stopping distances.
During take-off, they enhance wing camber, enabling shorter take-off runs.
Practise proper flap usage during training to develop muscle memory and instinctive control. Anticipate, fly smoothly, and maintain control at all times!
