What is screen height in aviation performance calculations?

Screen height is a reference altitude above the runway used to define the end of the takeoff or the start of the landing distance for performance calculations.

What are the standard values for screen height during takeoff and landing?

For takeoff, the screen height is typically 35 ft (dry runway, Class A); for landing, it is usually 50 ft above the threshold.

How does screen height affect obstacle clearance during takeoff?

Screen height represents the minimum height the aircraft must achieve at the end of the takeoff distance to ensure regulatory obstacle clearance.

Does screen height change for wet runways?

Yes, for wet runways the takeoff screen height is reduced to 15 ft to account for decreased acceleration and braking performance.

Why is the landing screen height sometimes reduced to 35 ft?

For steep approaches (descent gradients of 4.5° or more), regulations allow the landing screen height to be reduced to 35 ft.

Screen Height in Takeoff and Landing Performance

Medium4 min readPerformance Aeroplanes

Moderately Examined

Why this matters

Understanding screen height is essential for ensuring safe obstacle clearance during takeoff and landing, directly impacting runway performance calculations and operational safety margins.

Screen height is a reference altitude used in takeoff and landing performance calculations. For takeoff, it marks the minimum height an aircraft must reach at the end of the takeoff distance, ensuring obstacle clearance. For landing, it defines the standard height above the runway threshold where the airborne landing distance begins, typically set at 50 ft.

Quick Check

What is the standard screen height for takeoff performance calculations on a dry runway for a Class A aeroplane?

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In depth

Explanation

What is Screen Height in Aviation?

Screen height is a critical reference point in both takeoff and landing performance calculations. It represents a specific altitude above the runway—used to standardize performance data and ensure safe obstacle clearance.

Screen Height in Takeoff

For most jet and large transport aircraft (Class A), the takeoff screen height is 35 ft above the runway for dry conditions. This is the point by which the aircraft must reach a specified speed (V2) and demonstrate a positive climb gradient after an engine failure.
On wet runways, the takeoff screen height is reduced to 15 ft to account for decreased acceleration and braking performance, preventing excessive performance penalties.
The takeoff distance (TOD) is measured from brake release to the point where the aircraft passes through screen height.

Screen Height in Landing

The standard landing screen height is 50 ft above the runway threshold. This is where the airborne landing distance begins, and the aircraft is assumed to cross at the landing reference speed (VREF).
For steep approaches (descent angle ≥ 4.5°), the landing screen height may be reduced to 35 ft.
The total landing distance consists of the airborne distance from screen height to touchdown, plus the ground roll to a complete stop.

Performance Calculations and Obstacle Clearance

Screen height ensures that performance calculations provide a safety buffer for obstacle clearance at the end of takeoff and the start of landing.
It is a regulatory standard, not an actual obstacle height, but is used to verify that the aircraft's net flight path meets minimum clearance requirements.

Effects of Speed and Height at the Screen

Crossing the screen height too fast or too high during landing increases the airborne distance and total landing distance, potentially compromising runway safety margins.
Precise control of speed and height at screen height is essential for accurate performance planning and safe operation.

The essentials

Key Points

Screen height is a reference altitude used in takeoff and landing performance calculations.

Standard takeoff screen height is 35 ft (dry runway) and 15 ft (wet runway) for Class A aircraft.

Standard landing screen height is 50 ft above the runway threshold; reduced to 35 ft for steep approaches.

Takeoff distance is measured to the point where the aircraft passes through screen height at V2.

Landing distance starts at screen height and includes airborne and ground roll segments.

Crossing screen height too fast or too high increases landing distance and may compromise safety margins.

Screen height ensures regulatory compliance for obstacle clearance during critical flight phases.

Watch out

Exam Traps & Typical Mistakes

Confusing the takeoff and landing screen height values (35 ft vs 50 ft).

Assuming screen height is always the same regardless of runway conditions (not true for wet runways).

Believing screen height represents the actual height of obstacles rather than a regulatory reference point.

Mixing up the point where airborne distance starts (landing) or ends (takeoff) in performance calculations.

Thinking that screen height changes with increased V2 during takeoff—it remains constant.

Test yourself

Example Exam Questions

Question 2Easy

During landing performance calculations, what is the typical screen height assumed at the runway threshold?

Question 3Medium

If an aircraft crosses the threshold too high or too fast, what is the primary effect on landing distance?

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