A Recognized Air Picture or RAP is a (theoretically) complete listing of all aircraft

Aircraft

An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

 in flight within a particular airspace

Airspace

Airspace means the portion of the atmosphere controlled by a country above its territory, including its territorial waters or, more generally, any specific three-dimensional portion of the atmosphere....

, with each aircraft being identified as friendly or hostile, and ideally containing additional information such as type of aircraft, flight number

Flight number

A flight number, when combined with the name of the airline and the date, identifies a particular flight. This callsign should not be confused with the tail number of the aircraft, although both can be used as a call-sign as used in general aviation...

, and flight plan

Flight plan

Flight plans are documents filed by pilots or a Flight Dispatcher with the local Civil Aviation Authority prior to departure...

. The information may be drawn from a number of different sources, including military

Military

A military is an organization authorized by its greater society to use lethal force, usually including use of weapons, in defending its country by combating actual or perceived threats. The military may have additional functions of use to its greater society, such as advancing a political agenda e.g...

 radar

Radar

Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

, civilian

Civilian

A civilian under international humanitarian law is a person who is not a member of his or her country's armed forces or other militia. Civilians are distinct from combatants. They are afforded a degree of legal protection from the effects of war and military occupation...

 air traffic controllers, and allied nations or multi-national organizations such as NATO.

For the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 and Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

, the Recognized Air Picture is maintained continuously by NORAD at Peterson Air Force Base

Peterson Air Force Base

Peterson Air Force Base is a base of the United States Air Force located at Colorado Springs in El Paso County, Colorado, United States and it provides runways for the adjacent City of Colorado Springs Municipal Airport under a shared joint civil-military airport arrangement...

 (with Cheyenne Mountain

Cheyenne Mountain

Cheyenne Mountain is a mountain located just outside the southwest side of Colorado Springs, Colorado, U.S., and is home to the Cheyenne Mountain Air Force Station and its Cheyenne Mountain Directorate, formerly known as the Cheyenne Mountain Operations Center .Throughout the Cold War and...

 as a warm standby). In the United Kingdom

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, it is maintained by the United Kingdom Combined Air Operations Centre at RAF Air Command

RAF Air Command

Air Command is the only Command currently active in the Royal Air Force. It was formed by the merger of Royal Air Force Strike and Personnel and Training Commands on 1 April 2007, and has its headquarters at RAF High Wycombe, Buckinghamshire....

 at RAF High Wycombe

RAF High Wycombe

RAF High Wycombe is a Royal Air Force station, situated in the village of Walters Ash, near High Wycombe in Buckinghamshire, England. Its purpose is to serve the needs of the RAF Air Command, situated on the site. It is also the headquarters of the European Air Group...

. For the rest of Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, NATO has an Air Command and Control System

ACCS

ACCS is the $500M NATO Air Command and Control System programme, which is intended to replace the existing air command and control systems in Europe from 2009 onwards. At the highest level it comprises the Combined Air Operations Centre from which the air battle is run...

program underway to unify the various systems in use by NATO members throughout Europe.