Airport Engineering

Airport engineering plans and designs airfields. Learn site selection, runway orientation and wind coverage, runway length corrections (elevation, temperature, gradient), taxiways and aprons, airfield pavements, obstacle limitation surfaces and terminal planning.

An airport is a small city built around its runways. Aircraft need long, strong, level runways aligned with prevailing winds, clear approach paths, and pavements that survive loads far above truck axles.

ICAO and FAA standards govern almost every dimension of an airfield.

An analogy

A runway is like a take-off ramp tuned to air density: hot, high airports need longer runways because thin air gives less lift and thrust.

Airfield components

Runways, taxiways, aprons, terminal buildings, air traffic control, navigational aids (ILS, lighting), fuel and cargo areas. Runways are designated by magnetic heading (e.g. 09/27).

Runway orientation and length

Runways align with prevailing winds so that crosswind components stay within limits (e.g. 10–20 kt depending on aircraft) for 95 % of the time (wind rose analysis). Length is set by the critical aircraft and corrected for elevation, temperature and gradient; ICAO limits combined elevation + temperature correction to 35 % before special studies.

Airfield pavements

Flexible (asphalt) and rigid (concrete) pavements designed for aircraft gear loads (tens of tonnes per wheel, high tyre pressures). PCN reported by the airport must be ≥ ACN of aircraft using it (ACR/PCR in the new system).

Safety surfaces and capacity

Obstacle limitation surfaces (approach, transitional, inner horizontal) restrict building heights around airports. Runway end safety areas, runway capacity (movements/hour), parallel runway spacing and terminal/landside planning complete the design.

Formulas

• Elevation correction: +7 % per 300 m elevation
• Temperature correction: +1 % per °C of ART above standard (15 − 0.0065h)
• Gradient correction: +20 % per 1 % effective gradient
• Crosswind component: V_cross = V_w sin θ

Worked example: Runway length corrections

Given: Basic length 2100 m; Elevation 300 m, ART 33 °C, effective gradient 0.5 %

Find: Corrected length.

• Elevation: 2100 × 1.07 = 2247 m
• Standard temp at 300 m = 13.05 °C → rise 19.95 °C → 2247 × 1.1995 = 2695 m
• Check: 2695/2100 = +28 % < 35 % ✓
• Gradient: × 1.10 = 2965 m

Answer: ≈ 2965 m

Worked example: Crosswind

Given: Wind 30 kt at 30° to the runway

Find: Crosswind and headwind.

• Cross = 30 sin 30° = 15 kt
• Head = 30 cos 30° = 26 kt

Answer: 15 kt crosswind

Common mistakes

• Wrong: Orienting runways by terrain only. — Right: Use a wind rose to achieve ≥ 95 % usability.
• Wrong: Applying corrections without the 35 % check. — Right: Combined elevation + temperature above 35 % needs a specific study.

Applications

• New airports: Site selection, master planning and phased runway development.
• Runway extensions: Accommodating larger aircraft or longer routes.
• Airfield rehabilitation: Pavement overlays and PCN upgrades.

Key takeaways

• Orient runways with wind; limit crosswind.
• Correct length for elevation, temperature, gradient.
• Pavements rated by PCN vs aircraft ACN.
• Protect airspace with obstacle limitation surfaces.

Going further

• Wind rose analysis: Statistical wind data determines orientation and usability percentage.
• ACR/PCR: The new ICAO pavement rating system replacing ACN/PCN from 2024.
• Airside capacity: Runway occupancy time, separation standards and rapid-exit taxiways drive capacity.