Effective Runway Slope
Calculate a runway's effective slope, S = (max elevation − min elevation) ÷ length · 100, from the highest and lowest elevations along the runway centerline and its length. The effective slope is the difference between the highest and lowest points of the longitudinal profile divided by total length — a global measure of the incline the aircraft faces. It feeds directly into the runway length correction (+10% length per 1% effective slope), since an uphill runway needs more takeoff acceleration distance. ICAO limits effective slope by runway code (typically 1-2% max for higher codes) and also limits local slopes and their rate of change for safety. Geometric design minimizes effective slope and smooths transitions, balancing earthwork and drainage. Enter the maximum and minimum elevations and the runway length.
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Declividade efetiva de pista
A declividade efetiva de uma pista é S = (cota máxima − cota mínima) ÷ comprimento · 100 — a diferença entre o ponto mais alto e o mais baixo do perfil longitudinal da pista, dividida pelo comprimento total e expressa em porcentagem. É uma medida global da inclinação que a aeronave enfrenta ao longo de toda a pista, e não a inclinação local de um trecho. Esse parâmetro entra diretamente na correção do comprimento de pista: cada 1% de declividade efetiva exige mais 10% de comprimento, porque uma pista em aclive consome mais distância na aceleração de decolagem. A ICAO limita a declividade efetiva conforme a categoria (código) da pista — tipicamente no máximo 1% para pistas de código 3 e 4 (as maiores) e até 2% para as menores —, além de limitar as declividades locais de cada trecho e a taxa de variação entre trechos, para que a aeronave não perca o contato com o solo ao passar por uma lombada (efeito de 'pista ondulada') nem sofra esforços excessivos no trem de pouso. O projeto geométrico da pista busca minimizar a declividade efetiva e suavizar as transições verticais com curvas, equilibrando isso com o volume de movimento de terra e as exigências de drenagem (a pista também precisa de caimento para escoar a água da chuva). Informe as cotas máxima e mínima e o comprimento da pista.
Related Tools
Runway Hourly Capacity
Estimate a runway's hourly capacity, C = 3600 ÷ T, from the average occupancy or separation time between successive operations T (seconds). A runway's capacity — the maximum operations (landings and takeoffs) per hour — is one of the most important airport planning parameters, setting the airport's traffic limit. The time T is governed by minimum wake-turbulence separation, runway occupancy time (from touchdown to clearing via a rapid-exit taxiway), air traffic control procedures and the aircraft mix. Well-run single runways reach about 40-60 operations per hour; capacity rises with parallel runways, high-speed exits (reducing occupancy time) and optimized procedures. As demand nears capacity, delays grow nonlinearly (queueing theory), driving expansions or flow management (slots). Enter the average time between operations.
Approach Surface Height
Calculate the height of an approach surface (or other obstacle limitation surface) at a given distance, h = (gradient ÷ 100) · distance, from the ramp gradient (%) and the horizontal distance from the surface origin (m). Obstacle Limitation Surfaces (OLS) are imaginary inclined planes projected from runway thresholds and around runways, defined by ICAO, delimiting the airspace that must stay clear of obstacles for safe landing and takeoff. The approach surface, for example, rises at a typical 2% (1:50) gradient from the runway strip end; any object (building, antenna, tree, terrain) penetrating it is an obstacle to be removed, lowered, marked/lit or, ultimately, leading to operational restrictions. This calculation gives the maximum allowed surface height at each point, to compare with the actual height of existing or proposed obstacles around the airport — the basis of land-use control in airport protection zones and the assessment of new developments. Enter the gradient and the distance.
Take-Off Distance Available (TODA)
Calculate the Take-Off Distance Available, TODA = TORA + clearway, from the Take-Off Run Available (TORA) and the clearway length. TODA is one of the four declared distances of a runway, central ICAO operational concepts. The clearway is an obstacle-free rectangular area beyond the runway over which the aircraft can complete the initial climb to a minimum height — it extends takeoff distance without extra pavement, since the aircraft is already airborne. The declared distances (TORA, TODA, ASDA, LDA) are published for each runway threshold and used by pilots and dispatchers to verify, for each takeoff, that the aircraft — with its weight, configuration and the day's conditions — fits the available runway with required margins. Enter the TORA and the clearway length.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.