American Airlines ADS-B In system American Airlines
American Airlines has selected the ADS-B In system for retrofit on its 219 Airbus A321s and forward fit on its 100 A321neos on order. It installed the prototype ADS-B In guidance display just to the center left of the stack of larger displays above in an A330 simulator.

ADS-B Out Mandate Spurs Increasing Interest In ADS-B In

If pilots could see traffic around them, similar to what Air Traffic Control sees, would they like it? That is basically what ADS-B In provides

Printed headline: In or Out?


As airlines continue to equip their aircraft to meet the Jan. 1, 2020, automatic dependent surveillance-broadcast (ADS-B) “Out” mandate in the U.S. and June 7, 2020, deadline for most of Europe, interest appears to be growing to add ADS-B “In”—even in the absence of an FAA, International Civil Aviation Organization or European Aviation Safety Agency requirement. To appreciate this, it is a good idea to have some understanding of the two systems.

ADS-B Out equipage automatically broadcasts the position of the aircraft via satellite and ground stations to air traffic controllers. Essentially replacing outmoded radar systems, it gives the controllers a precise, real-time view of location, altitude and airspeed, allowing for more efficient flow control of a larger number of aircraft within a given airspace.

Adding ADS-B In would give pilots the ability to view, on a flight deck display, the presence of other nearby aircraft through receiving their precise ADS-B Out position information. The pilot can then input this information into applications such as CAVS (cockpit display of traffic information/assisted visual separation).

“ADS-B In gives pilots greater situational awareness,” says Terry Flaishans, president of Aviation Communication and Surveillance Systems (ACSS), an L3-Thales joint venture based in Phoenix. “Using GPS positioning data as to where traffic is located improves the accuracy of computing distances between aircraft, especially during a visual approach to an airport,” Flaishans says.

He notes that when using CAVS in conjunction with ADS-B In, pilots will be able to continue a visual approach, even if visual contact with the aircraft directly ahead is lost, thanks to the traffic information displayed onscreen.

American Airlines

American Airlines has selected the ADS-B In system for retrofit on its 219 Airbus A321s and forward fit on its 100 A321neos on order. It installed the prototype ADS-B In guidance display just to the center left of the stack of larger displays above in an A330 simulator.

Those benefits are why some airlines are taking notice—and acting. In May, ACSS announced a deal with American Airlines to provide its Safe-Route ADS-B In suite for retrofit on American Airlines’ 219 Airbus A321s, along with installing the system on the carrier’s 100 A321neos on order.

Originally, Flaishans says, ACSS had certified SafeRoute on American’s A330s, under a supplemental type certificate (STC). However, this version was for retrofit only and designed for a Class 3 electronic flight bag application. The new version to be installed on American’s A321s and A321neos uses existing flight deck displays, along with a unique ADS‑B In Guidance Display, which is sized to fit into any of the slots used by standby indicators for attitude, airspeed and altitude. The system is in the midst of the approval process by the FAA’s Los Angeles Aircraft Certification Office; certification under a technical standards order is slated for year-end. An STC for installation is expected during the first quarter of 2019.

“We believe the availability of CAVS approaches will more than cover the cost of the [SafeRoute] equipment and installation,” says Ron Thomas, managing director of American’s flight department “In addition, we are working to define CAVS+ to increase the use of visual approach-like operations, and with ACSS and the FAA in an AIRS [ADS-B In Retrofit Spacing] Project to demonstrate interval management capabilities.”

According to Chuck Manberg, ACCS senior staff engineer for advanced development, the company is talking with other commercial operators for potential application of Safe-Route on multiple platforms. “Our primary targets are the Airbus A319, A320, A321, A330 and the Boeing 737NG and MAX, but the solution is designed for most aircraft retrofit,” he says.

JetBlue Is In

New York-based JetBlue Airways also has opted for ADS-B In, having selected an airborne traffic situation awareness (ATSAW) solution, developed by Airbus. It is slated for forward fit on 85 A320/A321neos JetBlue has on order, with deliveries beginning in 2019. “It is an Airbus integrated ADS-B In solution, which works well with all of the existing interfaces and displays already on the aircraft,” says Chuck Cook, the airline’s general manager for communications, navigation, surveillance and technical programs.

Cook says ADS-B In will help JetBlue to “better its operational performance” in the heavily congested U.S. Northeast corridor, which extends from Washington north through Philadelphia, New York and Boston. “It is understood that as the Northeast Corridor goes, so goes the rest of the national airspace,” he remarks.

Shorter in-trail separation of aircraft is also cited as an ADS-B In benefit. “For example, if a pilot wants to cruise at a more fuel-efficient altitude, the information generated and displayed by ADS-B about traffic at that altitude will enable him to provide that to an air traffic controller,” Cook says.

As for retrofitting JetBlue’s fleet of A320s/A321s, as well as its Embraer jets, Cook says that “further implementation of ADS-B In” is under study.

“Before a business case can be made for fleet-wide retrofit, a number of factors must be considered,” he says. When the FAA approves the operational procedures available via ADS-B, then the airline will consider additional retrofits, Cook notes.

Optional or Standard?

At Boeing, the 787 has been the initial application of ADS-B In. Starting with Line No. (L/N) 369 of 787 production, all have been delivered with a Rockwell Collins integrated surveillance system (ISS) with receiver sensitivity that supports an ADS-B In option, available at either forward or retrofit. Of the 700 787s built as of May 1, more than one-third have ADS-B In. Of the last 340 built, about 50% have the ISS with ADS-B In capability.

The airframe OEM has made a retrofit kit available for ADS-B In under a service bulletin, according to Bill Richards, a technical fellow for avionics/air traffic management with Boeing Commercial Airplanes. “For all 787s, starting with L/N 369, little more than a software update to the ISS will be needed. However, prior to that number, replacement of the original ISS with the new ADS-B In-capable ISS will be required,” he says.

Boeing has offered the ADS-B In receiver and ADS-B In applications option on the 787 since November 2015, and plans to offer them on the 777X, which will enter service in 2020. Richards adds that a trade study is planned with respect to an ADS-B In option for the 737 MAX. 

Asked about the possibility of ADS‑B In as standard equipment, instead of an option, on all-new-build aircraft, Richards ventures that it “could be at some point in the future, due to its enhancement of situational awareness of the surrounding airspace.” At the same time, he points to interval management capability, giving air traffic controllers the ability to work with pilots to optimally space aircraft when on approach to the terminal area.

“Multiple aircraft could be spaced on the basis of a specific time or distance interval behind one another, eliminating the vectored approaches done today,” he says. “But this would require greater aircraft system complexity, and a number of changes on the ground.”

Enhanced situational awareness is, at this time, the basic incentive for ADS‑B In, says Mike McDowell, technical marketing manager, communications, navigation and surveillance avionics-Commercial Systems for Rockwell Collins. “In the future, I expect that the selection of some ADS‑B In applications will be driven by the philosophy of ‘best equipped/best served,’” he notes. So an aircraft equipped with capabilities others do not have will be given priority handling at a busy airport at peak traffic times, he says.

Retrofit Market

The retrofit market for ADS‑B In has not been very strong because the situational awareness benefit is viewed as a “nice to have” feature, says McDowell. However, he stresses that when advanced features are available and ADS-B In’s overall economic benefit is recognized, the retrofit market will expand. Forward fit, he adds, is a different story: “If the capability is available at an aircraft’s entry into service, the airline will be more likely to select ADS-B In, as is the case with the 787 and 777X.”

In that regard, Mark Lynch, head of engineering for aircraft leasing giant GECAS, cites very little demand for ADS-B In retrofits. “As it is not driven by a mandate, ADS-B In is not likely to be high on the list of requirements, which is typical for nonmandated upgrades,” he says. 

Typically, strong (retrofit) demand only occurs within 2-3 years of a mandate deadline, says Lynch. However, early adopters risk installing solutions that may not meet the mandate when published, which requires further retrofit, he cautions.

“Operators are therefore likely to wait until there is a clear mandate, or a compelling economic argument for embodiment, and then embody it as a fleet solution to all their aircraft, including those leased,” he says. “They may at that point be entitled to a contribution by the lessor, depending on the lease details.”

Swiss International Air Lines is among those carriers still uncertain about ADS-B In. For a Eurocontrol-sponsored ATSAW project in 2012‑14, the Zurich-based airline equipped three of its A330-300s with ADS-B In avionics. During the period, those airplanes operated more than 1,500 North Atlantic flights. 

The main focus for Swiss was on “the improved situational awareness and the in-trail procedure [ITP] applications within North Atlantic airspace,” says Joerg Neubert, the airline’s head of projects and development for the flight operations engineering department. While both tests were successful and flight-crew feedback was positive, Neubert points out that changed separation standards and requirements on the North Atlantic routes—specifically longitudinal and lateral separation minimums, and performance-based communication and surveillance—have had a negative impact when it comes to ITP application.

“Swiss is closely monitoring the development of new ADS-B In applications, especially for the airport surface. A decision about the ADS-B In implementation on additional aircraft will be made at a later stage,” Neubert says. 

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