Thursday, July 17, 2008

Improved Air Traffic Control with Cooperative Surveillance Techniques

Stephan Schulz from Comsoft GmbH, Germany, will talk about Air Traffic Control, 2008-08-06 at NICTA in Canberra:


Improved Air Traffic Control with Cooperative Surveillance Techniques

Stephan Schulz (Comsoft GmbH)

DATE: 2008-08-06
TIME: 16:00:00 - 17:00:00
LOCATION: NICTA - 7 London Circuit

Aircraft in controlled airspace are flying under the direction of air traffic controllers, which are responsible for safe, orderly, and expeditious traffic flow. In particular, maintaining proper aircraft separation is not left to individual pilots, but subject to air traffic control.

To support controllers in their task, surveillance systems are used to provide an air situation picture. The quality of the air situation picture determines both the workload of the controller and the safe separation limits of aircraft, and hence significantly influences the safe capacity of the air space. Most of todays surveillance systems are based on rotating antenna radars. However, radars are expensive to build and operate. They have a relatively low update rate and limited scalability.

New surveillance techniques rely on cooperative aircraft to overcome this disadvantage. Multilateration systems use a scalable array of small, low-cost sensors to determine aircraft position and parameters from the time difference of arrival of aircraft transponder signals. They achieve high accuracy, can provide updates several times per second, and provide secondary information about the aircraft based on the content of the received messages.

An even more radical departure from classical radar is Automated Dependent Surveillance - Broadcast. With ADS-B, the aircraft determines its own position using a global navigation satellite system. It broadcasts this position and auxiliary information, typically several times per second. The signal can be received by a low-cost ADS-B ground station with a simple omni-directional antenna. Thus, a small, passive sensor can provide a high-quality air situation picture.

Stephan Schulz studied computer science and physics at the University of Kaiserslautern and graduated (Dipl. Inform.) in 1995. In the same year he joined the Automated Reasoning Group at the Technical University Munich. In 2000 he obtained a Ph.D. in computer science for his work on learning search control strategies for first-order deduction. He has contributed to the development of several high-performance deduction systems. Dr. Schulz is best known for developing E, one of the most friendly theorem provers for first-order equational logic. He taught at TU Munich, the University of Miami, and the University of the West Indies.

In 2005 he joined Comsoft GmbH, a German provider of solutions in he field of air traffic control, where he now is responsible for research and development of future surveillance technologies.

1 comment:

Tom Worthington said...

Stephan Schulz, gave a useful introduction to problems with radar for air traffic control. He discussed primary and Secondary Surveillance Radar. (SSR) This was by way of an introduction to the benefits of Automatic dependent surveillance-broadcast (ADS-B)
He perhaps spent a little too long on the basics before moving on to interesting advanced applications of ADS-B to replace radar using multiple ground stations. My main contribution to the project was to point out to the controllers used to analog systems, that they did not need to put a cross on the screen with a grease pencil to mark a crash site. ;-)

While useful, Stephan's analysis is less relevant to Australia, where there are very large distances compared to Europe. Any ground based system is going to be too expensive to cover all of Australia.

Stephan pointed out that UPS and Fedex are using ADS-B in the air with Cockpit Display of Traffic Information (CDTI) in their freight aircraft. This gives a display to the pilot similar to that the air traffic controller would see on the ground.

It occurred to me that if aircraft are receiving the ADS-B signals from other aircraft around them, they could then relay this information to ground controllers, using an air-to-ground or satellite radio link. A modern aircraft would only require a software update to do this, with no extra hardware being needed. Only a few aircraft equipped this way would need to be in the air at a time to provide complete coverage. Aircraft makers and operators may be willing to go to the cost and trouble to fit aircraft with this, if that allowed them more flexibility in the fling (due to greater coverage) and the air traffic controllers would get the service for free. At question time I asked if this would be feasible and he liked it as a research topic, but commented that safety considerations would make it difficult to be accepted.