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What is air traffic control?

Air traffic controllers are ground-based staff, operating from a control tower. They co-ordinate and organise the movements of aircraft, making sure that they fly within a safe distance from each other, thus avoiding any collisions.  They also direct flights during take-off and landing, relay information to pilots and direct them around bad weather.

How does air traffic control work?

Air traffic control is a complex system.  A controller uses radar screen systems to display all the aircraft flying in their particular sector at a given time – airspace is divided into zones and each zone is divided into sectors.  The airspace that they work in is called controlled airspace.  Although the systems they use display information in 2-D, the air traffic controllers have to think in 3-D; what may look like two aircraft nearly colliding on the screen, may in fact actually be a thousand feet apart from each other in reality.

Modern aircraft also have collision avoidance systems that serve as a backup to an air traffic controller’s radar system, but pilots still rely on air traffic control during a flight.  Although air traffic controllers are responsible for emergency monitoring, the pilot has the final call for the safety of the flight, however, and may deviate from instructions given in an emergency.

Departure

The air traffic controller uses visual observation before a flight departs, to assess whether the runway is clear for a flight to taxi into position.  They also use radar to check that the departing aircraft won’t get in the way of landing aircraft.  The air traffic controller then gives the aircraft clearance to depart.  Once the flight has taken off, the pilot activates a transponder in the cockpit, which sends a radar signal with the flight’s number, altitude, airspeed and destination to radar towers located along the plane’s route.  The airplane will appear as a dot on the air traffic controller’s radar screen systems.  As the aircraft travels through various airspaces, the plane is passed from one air traffic controller centre to another, until it finally reaches its destination.

Arrivals

The signal of a descending aircraft gets picked up by the air traffic control centre, at the arrival airport.  The air traffic controller can see the number of aircraft in the airspace surrounding the airport and the number of planes on the ground.  With this information, the controller safely guides an arriving aircraft into the airport and may relay instructions to the pilot depending on the weather conditions.

When we’re off on our travels, it’s quite easy to take for granted how we get from A to B, but a lot of careful co-ordination is going on behind the scenes, to make sure we get to our destinations safely.

This post was written by James Harper on behalf of Lee-Dickens who provide emergency monitoring software and other systems comonly used in air traffic control and industry. Photo: dno1967b

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Helmond Castle is everything you expect from a visit to the typical medieval castle. All archaeological treasures, replicas, guns, tools, pictures, paintings and other historical items that you can see here, will give you the opportunity to have a concrete idea of ​​life at the Castle Helmond. In combination with the view of this picturesque castle, your visit gets an unforgettable experience.

Helmond Castle has a square floor plan, in the corners there are rounded towers and is completely surrounded by the moat. There are other similar castles in the Netherlands, for example Ammersoyen Castle, Muiden Castle and partially preserved Radboud Castle. Helmond Castle’s walls are only 1.3 meters wide, therefore the castle has originally a double moat. This kept cannons during a possible attack at a safe distance from the castle.

Helmond Castle also serves as a museum, which is located in the basement of the castle. You will find here something about the history of the castle and the city of Helmond and art gallery.

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Helmond Castle was built around 1420 by the family Van Berlaer to replace their former castle. This, originally wooden fort, was already built in 1350 and its remains were found during the excavation about 250 m southwest of the castle. In 1549 Helmond Castle was strongly damaged by fire. During The Eighty Years’ War the castle was on the side of Spain. The castle was under siege several times in its history, in 1581 even by the government troops. Although the city of Helmond was conquered, Helmond Castle was not, so the army had to leave the town.

In 1587 the soldiers came back again, but the castle remained unconquered again. Thus, despite the thin walls, Helmond Castle was very well situated from a military point of view. In 1602, however, luck turned. The castle was besieged by the government troops under the command of Prince Maurits. He used six cannons. All 45 soldiers at the castle was forced to surrender. All those sieges caused many damages. In 1603 the castle was conquered again, this time by the soldiers of the Walen.

This happened during the reign of the family Van Cortenbach who were not much interested in the Castle Helmond, mostly because its members lived on their sites in the southern Netherlands (today Belgium). Therefore, in the 18th century, they sold the Castle Helmond to the lower nobles of Utrecht. He renovated and re-arranged the castle and his heirs lived here until 1920, when it was sold to the city council. They established a city hall here. Since 1982 Helmond Castle does not serve as the town hall anymore, but still hosts weddings and other festive ceremonies.

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