Load Factor

Load factor is the ratio of the lift an aircraft produces to its actual weight. Pilots express it in "g's," where 1g means the aircraft is supporting exactly its own weight in straight and level flight.

How It Works#

Every aircraft in steady, level flight has a load factor of 1g. The wings produce just enough lift to equal the aircraft's weight. Nothing changes until the pilot maneuvers.

When a pilot banks into a turn, the wings must support the aircraft's weight and keep it turning. Lift tilts inward, so the vertical component of lift decreases. To maintain altitude, the pilot must increase total lift. That extra lift raises the load factor above 1g.

The relationship follows a simple formula. If the bank angle is $\phi$, then:

$n = \frac{1}{\cos\phi}$

where $n$ is the load factor. At a 60-degree bank, $\cos(60°) = 0.5$, so $n = 2g$. The wings are carrying twice the aircraft's weight.

Load factor also raises stall speed. Stall speed increases with the square root of the load factor:

$V_{s(n)} = V_{s} \times \sqrt{n}$

At 2g, stall speed rises by about 41%. At 60 degrees of bank, an aircraft that stalls at 50 knots in level flight will stall near 71 knots instead.

Example in Aviation#

A student pilot enters a steep 45-degree banked turn during a training flight. The load factor climbs to approximately 1.41g. The instructor points out that stall speed has increased by about 19%. If the student flies too slowly or pulls back too sharply, the aircraft can stall at a speed that felt safe moments earlier. This is why steep turns require both coordination and an awareness of airspeed margins.

Why It Matters#

Every aircraft has a maximum certified load factor, defined in its flight manual. Exceeding it risks structural damage, even if the aircraft feels fine from the cockpit. For a typical light training aircraft, the positive limit is 3.8g under normal category certification.

Load factor also connects directly to stall awareness. Many accelerated stalls and loss-of-control accidents happen because pilots do not recognize how a steep bank or a hard pull compresses their safety margin. Understanding load factor turns an abstract number into a concrete, practical risk.

Key Takeaways#

• Load factor is lift divided by weight, measured in g's.
• Straight and level flight always equals 1g.
• A 60-degree bank doubles the load factor to 2g.
• Higher load factor raises stall speed. At 2g, stall speed increases by 41%.
• Every aircraft has a structural load limit. Exceeding it can cause permanent damage.