The haze between Mode S and UAT ADS-B

Does Surveillance and Broadcast (SBS) want you to know about the real ADS-B?

By Rob Stapleton
ANCHORAGE, AK (Sept. 27,2009) Federal Aviation Administration spokesperson Dave Bowen wrote and interesting piece and posted it in the Federal Times.com on Sept 21.

Bowen correctly informs pilots and aircraft owners of ADS-B's capabilities when used with the Universal Access Transceiver and is using both 1090 MHz and 978 MHz. There is a misconception that ALL ADS-B coverage is the same and will be the next best thing to sliced bread (for air traffic control and surveillance). Many do not realize that ADS-B will at first be a transmit only system thus only taking advantage of the radar like service only.

Bowen perspective is interesting as most of the ADS-B that will be offered in the U.S. will be similar to Mode S, and will only transmit in real time a location not allowing for additional services, such as TIS-B, FIS-B and transmit and receive information from other like equipped (UAT) aircraft. In the future both the FAA and ITT who has the multi billion contract to install the equipment nationwide have said the services like current weather, email, and other situational awareness service could be provided by subscription in the future.

Bowen states: The Federal Aviation Administration is working with U.S. airlines to get them to put ADS-B equipment in their aircraft and, in return, is enabling more straight-line routing, which results in shorter flying times and reduced fuel burn, saving millions of gallons of fuel per year. We are also developing and publishing more GPS-based airport approaches each year, and these now outnumber our published approaches based on ground-based navigation equipment.
ADS-B is already operational in Alaska, where the population depends on aviation to a far greater extent than in the continental U.S. It will soon be deployed in the Gulf of Mexico. FAA intends to deploy ADS-B over the continental U.S. in the next few years; it started in Miami, Florida last fall.
FAA’s NextGen initiative is far more than just ADS-B — it will enable digital communication, digital weather modeling and other capabilities. It will support a level of air traffic that is magnitudes more than current levels — safely, efficiently and effectively. NextGen will be less costly to operate and generate significant fuel savings for air carriers and other users of U.S. airspace. NextGen is the path that FAA will take to fly into the future.

Many airlines do not support the re-equipage of their aircraft with ADS-B UAT technology as they are equipped with Mode C and Mode S which offers similar coverage. The added expense of changing their equippage is one argument, that seems to be floating around, the other is the hazy smokescreen of misinformation about the real ADS-B as it is used in Alaska today--with UAT.
Some argue that where 'the rubber meets the road' in an argument, is that in a crowded corridor, Mode S only has so much bandwidth and can easily be choked up with multiple contacts.
This limitation only supports the use of both the 978 MHz UAT and 1090 MHz frequencies and the use of the UAT technology for its potential services.