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 distribution to transmit electrical energy across large distances. It consists of one or more uninsulated electrical cables (commonly multiples of three for three-p ...

crossings, telecom towers or

wind turbine A wind turbine is a device that converts the kinetic energy of wind into electrical energy. Hundreds of thousands of large turbines, in installations known as wind farms, now generate over 650 gigawatts of power, with 60 GW added each year. ...

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 The Federal Aviation Administration (FAA) is the largest transportation agency of the U.S. government and regulates all aspects of civil aviation in the country as well as over surrounding international waters. Its powers include air traffic m ...

approved Audio Visual Warning System (AVWS) approved in the National Airspace. OCAS is also the only AVWS approved by the

International Dark Sky Association The International Dark-Sky Association (IDA) is a United States-based non-profit organization incorporated in 1988 by founders David Crawford (astronomer), David Crawford, a professional astronomer, and Tim Hunter (astronomer), Tim Hunter, a physi ...

. 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 Uni ...

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 speed of an aircraft relative to the Earth’s surface. It is vital for accurate navigation that the pilot has an estimate of the ground speed that will be achieved during each leg of a flight. An aircraft diving ve ...

, 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. They may be advisory or compulsory and are normally laid down by an advisory or regulatory body that may be either voluntary or statutory. In ...

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