ADS-B bridges the Gulf of Mexico

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Louisiana-based oil and gas industry giant Petroleum Helicopters (PHI) took its flight operations safety to a new level on 17 December without so much as adding a single new antenna on its helicopters.

Using existing VHF radios and with internal changes to the Universal Avionics-built flight management systems and Mode S transponders on more than a dozen helicopters, PHI pilots from that date were able to talk to air traffic controllers in Houston, who see them on virtual radar, as they fly to increasingly distant platforms in the Gulf of Mexico.

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The new-found vision is courtesy of the Federal Aviation Administration's roll-out of automatic dependent surveillance - broadcast infrastructure in the USA.

Houston and the Gulf of Mexico represent the second initial operating capability for ADS-B "critical" services, meaning the use of aircraft-transmitted GPS-based position, altitude and speed data for air traffic separation and management.

The FAA approved the Louisville, Kentucky terminal radar approach area for critical operations, allowing early adopter UPS to begin taking advantage of the technology.

The agency last year began offering ADS-B "essential" services, which include the piping of nearby air traffic and government-provided weather data into the cockpit for suitably equipped aircraft, in southern Florida. ADS-B contractor ITT plans to have the entire continental USA ready for essential and critical services in 2013.

Surveillance and other services are key to safety and efficiency in the Gulf, where range-limited radar does not pick up low-flying aircraft, traditional radio communications are not available, weather can change rapidly and where instrument flight rules options today are cumbersome to the point of being impractical.

INADEQUATE CONDITIONS

With more than 10,000 workers a day trying to move among at least 3,700 active oil fields and rigs in the Gulf, however, the transport show must go on, raising fears that visual flight rules flights can take place in inadequate conditions as a result of a lack of information or an economic need to complete the mission.

The FAA four years ago kicked off the programme by signing a memorandum of agreement with Helicopter Association International (HAI) and the Helicopter Safety Advisory Council, a group made up of Gulf of Mexico operators. The FAA's role was to develop, install and maintain the ADS-B infrastructure as well as voice communications and weather reporting system.

For their part, the operators agreed to provide transport to and from the platforms, physical space, electricity and voice and data transmission devices to link the platforms to the FAA's Houston air route traffic control centre, a contribution totalling more than $100 million over the four years, says HAI president Matt Zuccaro. Operators most often connect to the mainland using satellite links.

"Over the past 50 years, air traffic controllers couldn't see and talk to aircraft in the Gulf," says Zuccaro. "There was no real-time weather. Individual operators had the responsibility to deploy their own systems, which led to a stove-piped patchwork of systems."

For IFR flights, the FAA created a virtual grid system using GPS waypoints over the Gulf, where for all practical purposes only one aircraft at a time could occupy a route composed of 37 x 37km (20 x 20nm) blocks of gridded airspace, closing an entire route until that particular aircraft would report landing via an operator's communication network.

PHI was the first helicopter operator in the Gulf to begin equipping its aircraft to transmit the ADS-B "out" data. "Before, Houston centre couldn't see us, which slowed down and hindered operations, making it impractical to go IFR," says Mike Hurst, chief pilot for PHI. "ATC had to take them on circuitous routes to maintain separation. Flight plans indicate if an aircraft is ADS-B equipped, and if it is, that aircraft gets priority over non-equipped aircraft."

The so-called "best-equipped, best-served" concept is a key selling point the FAA has been using to attempt to get both the fixed- and rotary wing communities to buy ADS-B units before initial mandates in the 2020 timeframe. As proposed, the ADS-B "out" rule will require all aircraft to equip with 1090Mhz "extended squitter" transponders or 978MHz universal access transceivers by 2020.

Since initial operating capability in December, Hurst says PHI helicopters have used the ADS-B IFR services "almost every day", but also use the technology for surveillance under visual flight rules to boost safety.

So far, the company has equipped 13 helicopters, modifying the flight management system in each to send the WAAS GPS-derived position, altitude, speed and other data at 1s intervals out through the aircraft's Mode S 1090MHz transponder, which is then picked up by receivers on ITT-installed ADS-B stations.

Kim Pettis, an FAA controller at Houston, says having the surveillance data allows her to provide faster separation services. "We don't have to delay in waiting to get them clearance to get out or to get back in," says Pettis.

The FAA has 80 controllers trained to provide the ADS-B services using three low-altitude sectors and up to two high-altitude sectors covering the Gulf's 428,000km2 (165,000 miles2).

Although operational, the government's work in the Gulf is not complete. The FAA plans to install five additional ADS-B stations to complement the 16 already in place on oil platforms or on the shore line; three additional VHF radio stations for receiving and relaying voice communications, adding to the six already in place, and 35 automated weather reporting stations, up from 21 in place now.

Industry so far is happy with the FAA's performance on the project. "They said they were from the government," says HAI's Zuccaro, talking about the FAA's persistence throughout the project. "And they really did come here to help."