The Obstacle Collision Avoidance System (OCAS) is designed to alert pilots if their aircraft is in immediate danger of flying into an obstacle. OCAS uses a low power ground-based radar to provide detection and tracking of an aircraft's proximity to an obstacle such as high buildings,

power line An overhead power line is a structure used in electric power transmission and Electric power distribution, distribution to transmit electrical energy along large distances. It consists of one or more electrical conductor, conductors (commonly mu ...

crossings, telecom towers or

wind turbine A wind turbine is a device that wind power, converts the kinetic energy of wind into electrical energy. , hundreds of thousands of list of most powerful wind turbines, large turbines, in installations known as wind farms, were generating over ...

s. This capability allows the visual warning lights to remain passive until an aircraft is detected and known to be tracking on an unsafe heading. OCAS is currently the only FAA approved Audio Visual Warning System (AVWS) approved in the National Airspace. OCAS is also the only AVWS approved by the

International Dark Sky Association DarkSky International, formerly the International Dark-Sky Association (IDA), is a United States–based nonprofit organization incorporated in 1988 by founders David Crawford (astronomer), David Crawford, a professional astronomer, and Tim Hunt ...

. OCAS is operational in the US, Canada, Norway and Germany. OCAS developer was acquired by

Vestas Vestas Wind Systems A/S is a Danish manufacturer, seller, installer, and servicer of wind turbines that was founded in 1945. The company operates manufacturing plants in Denmark, Germany, the Netherlands, Taiwan, India, Italy, Romania, the Un ...

in 2011.

Overview

The OCAS system is designed to protect obstacles that are vulnerable to low flying aircraft. OCAS detects the

ground speed Ground speed is the horizontal component of the velocity of an aircraft relative to the Earth’s surface, also referred to as "speed over the ground". It is vital for accurate navigation that the pilot has an estimate of the ground speed that wil ...

, heading and altitude of approaching aircraft and determines whether it will adequately clear the obstacle. A configurable set of rules is applied to define and determine when to warn the aircraft, by which warning device and signal depending on the calculated time to impact with the obstacle. Initial WarningMedium Intensity Lighting: Once the initial threshold is met, the visual warning is activated. This capability allows the lighting system to remain passive (in the off position) the vast majority of the time thus preserving the dark sky environment while adhering to strict

safety standards Safety standards are standards designed to ensure the safety of products, activities and processes, etc. Additional descriptive terms may help to clarify what hazards are being addressed, such as workplace safety standards (to keep workers safe), ...

set out by the FAA. Secondary Warning{{sndAudio Broadcast: If the initial warning does not result in the pilot altering the flight path, a programmable VHF radio broadcasts an additional obstruction warning directly to the cockpit. The VHF warning frequencies are adjusted based on local requirements.

References

Aviation safety

Overview

See also

References