Commercial

A380 Innovations: A Balancing Act

By Charlotte Adams | March 1, 2003

The giant Airbus 380 features subtle cockpit design. It balances new concepts and technologies within an existing framework to provide a familiar, yet easier-to-use pilot workspace. The human-machine interface (HMI) is interactive and intuitive, reflecting "a cockpit designed around the pilot," says Jean-Francois Desmoulins, Airbus cockpit functions manager. "The key to our approach in creating the A380 cockpit is to maintain commonality with other Airbus aircraft, while embracing new technology where it brings worthwhile benefits."

Another innovation is the open Integrated Modular Avionics (IMA) concept, which will help to reduce support costs and make upgrades easier. Applicable to multiple aircraft functions, IMA includes elements developed by Rockwell Collins (high-speed bus switches), Thales Avionics (IMA modules) and internal Airbus supplier EYY (IMA modules). The Honeywell-developed surveillance system also represents a leap in capability and design.

The avionics systems are built on large computing resources and a two-way, deterministic, 100-megabit/sec backbone. This avionics full-duplex (AFDX) switched Ethernet bus will move massive volumes of data, enabling the manipulation of large databases to drive the high-resolution, real-time Thales displays. Yet there is still margin for growth, to incorporate new features and functions, says Desmoulins.

RNP Certification

Airbus plans to certify the airplane to 0.3 RNP (required navigation performance) in the approach phase, RNP 1.0 for ascent and descent, and RNP 4.0 for cruise flight. But the A380 will have the ability to achieve 0.1 RNP if that should be required by international standards.

The avionics systems are still in development, so there will be more to say as the A380 nears first flight in 2005. Entry into service–with Singapore Airlines–is expected in the second quarter of 2006. As of January, Airbus claimed 86 orders for the passenger version, 17 for the freighter version, and more than 50 options, a record number this early in the program.

At press time aircraft electronics systems not yet awarded included the optional head-up display (HUD), the in-flight entertainment (IFE) system, the Onboard Information System (OIS) and the Network Server System, which supports the OIS. OIS terminals, located on the far left and right of the cockpit, will host operational documentation, flight crew operating manual, minimum equipment list, navigation charts and other information. In late January Smiths Aerospace was tapped to supply a concentrator and multiplexer unit that permits the display of video functions on the primary cockpit displays. Inputs include taxi aid video, cockpit door surveillance, smoke detection video, cabin video and airport nav chart graphics.

Airbus emphasizes the commonality between the A380 and other Airbus cockpits, such as similar general layout, similar arrangement of screens and controls, identical symbology and color coding, and dark cockpit philosophy. The A380 also uses the sidestick controller familiar to A330 and A340 pilots. This commonality will enable pilots to transfer from the A330/A340 family to the A380 in six to 10 days, less than the 25 days required for transition training without commonality, Airbus says.

But cockpit changes are equally striking. The cockpit display system (CDS) will feature eight 6-by-8-inch liquid crystal displays (LCDs), rather than six 6-by-6-inch displays. These comprise two primary flight displays (PFDs), two navigation displays, one engine parameter display, one system display and two multifunction displays (MFDs). All the displays are identical, interchangeable and potentially interactive.

The lower 2-by-6-inch area of the displays can be used to provide a window, showing additional information, "soft" keys or dialog boxes. An air traffic control (ATC) mailbox, for example, is provided at the bottom of the system display. The lower area of the PFD will present information such as flap and slat position and flight limitations following a system failure.

New on the A380 are the two MFDs at the center of the front panel, flanking the system display. The MFDs provide an easy-to-use interface to the flight management system (FMS)–replacing three multifunction control and display units (MCDUs). (A larger FMS interface was a key issue in the cockpit design.) The FMS pages will have ease-of-use features, such as folder tabs that allow quick access to groups of related functions. The MFDs also provide a full-page interface to ATC communications and surveillance functions, as well as a backup interface to the flight control unit (FCU), used to control the autoflight (autopilot) system and the electronic flight instrument system (EFIS). The ATC mailbox will replace the two data link control and display units (DCDUs) previously used for ATC messaging.

The cockpit display system also is designed to be reconfigurable. In the case of an MFD failure, for example, the interfaces to the FMS, surveillance system, ATC and (backup) FCU–which the MFD had supported–will become accessible through the navigation display.

Thales plans to deliver the first four complete cockpit systems–including the PFD, systems displays and "test" screen presentations–by mid-2003 for use on Airbus integration rigs. Each system includes eight displays and two keyboard and cursor control units (KCCUs). Thales is implementing the commercial aviation cockpit display standard, ARINC 661, which supports interactivity and permits display presentation software to be developed independently from the underlying hardware and core graphic software. The FCU, also supplied by Thales, will be delivered in June 2003. The glare shield-mounted panel is independent from the cockpit display system.

Vertical Position/Weather

Another striking feature in the A380 is the vertical position/weather display, in the lower portion of the navigation display. It presents a vertical profile of the flight path, with altitude on the vertical axis and distance on the horizontal axis. Terrain information provided by the terrain awareness warning system (TAWS) database is painted in brown along the bottom, the flight path is projected in green, and the aircraft icon is drawn in yellow.

Airbus plans to present vertical weather simultaneously on the display, fed by the weather radar data. This will allow pilots to see weather not only horizontally (on the main navigation screen) but vertically, at other altitudes, for additional situational awareness, especially in ascent and descent.

The main navigation display presents weather radar or terrain data, each of which can be overlaid with traffic data from the traffic collision avoidance system (TCAS). The nav display also will be capable of presenting airport moving maps as a continuation of the aircraft’s flight plan. Provisions have been made for this, but a certification date has not been determined.

Interactivity

Perhaps the most unique new cockpit feature in the A380 is the interaction with the FMS system through the navigation screen. Integral to this change is the Thales-designed KCCU, which includes a keyboard with dedicated FMS and other function keys and a QWERTY pad, plus a hand rest with a trackball for moving the cursor on the MFD and a mouse button for clicking the cursor. The KCCU also features left and right arrow keys to move the cursor from screen to screen, mainly between the nav screen, the MFD and the system display containing the ATC mailbox.

The pilot will be able to interact with the FMS through the navigation screen to modify waypoints, viewing the temporary (and permanent) flight plans. The navigation display will feature menus of choices, allowing pilots to delete a waypoint or insert a hold, for example, rather than interact with lists of data on an MCDU.

Although the exact look of the menus and soft keys may change, the process of interaction will proceed along the following lines. If the pilot clicks on a waypoint icon on the main navigation screen, options, such as "insert hold," "direct to," or "insert waypoint," will pop up on the screen next to that symbol. When the pilot chooses the "insert hold" option, a navigation dialog box replaces the vertical display at the bottom of the screen. This dialog box allows more information about the choice to be entered, such as how long a leg the pilot will have to make or when he or she expects further clearance. Interactions with the FMS via the nav screen, however, will be limited to "tactical" modifications like changing waypoints. Strategic activities, such as changing the whole flight plan or doing what-if analysis, will be performed on the MFD.

The FMS builds on Honeywell’s Pegasus system, already certified on the A340, A330 and A320 series. Central processor speed and memory capacity are expected to more than double on the A380, compared with Pegasus. The navigation database could be two to four times larger. The company also is shooting for a meantime between failure (MTBF) of 35,000 hours (March 2002, page 11).

AESS

The Aircraft Environment Surveillance System (AESS), also supplied by Honeywell, includes weather radar, terrain warning and TCAS/Mode S transponder functions in an 8-MCU enclosure, two of which are installed on each aircraft. Although the systems are packaged as separate circuit card assemblies within the box, they are integrated at the data level. The weather radar, for example, uses information in the terrain database to automatically remove terrain clutter in the radar return, to optimize the weather display, says Lyle Kendall, Honeywell’s AESS product line manager.

Honeywell’s next-generation weather radar system accrues and stores weather data, unlike most current designs, which can’t save their data or add to it. This radar data is "volumetric" or "three-dimensional," because it is built from–and constantly updated by–systematic, left-to-right scans of the area in front of the airplane at a range of elevation angles. Typically, weather radars paint and repaint the results of single, left-to-right scans at an optimized elevation angle, while the next-generation radar builds the equivalent of a cube in space. Large volumes of radar data are stored in a "3-D buffer," so that the information can be manipulated from different perspectives. This database feeds the plan view weather display, as well as the vertical position display, allowing the pilot to see the weather not only at the current cruise altitude (God’s eye) but also at other altitudes.

At full functionality, the vertical display will show TAWS-drawn terrain across the bottom of the screen and layers of weather–a spattering of greens, yellows and reds–above, against an altitude/forward distance grid. Functional integration allows the system to "paint a picture that shows a vertical view of both terrain and weather," Kendall explains.

Honeywell expects to deliver the system to Airbus in November 2004, but already has growth options in mind. A "smart alerting" function, for example, could arbitrate between conflicting alerts–such as a TCAS command to descend and a TAWS command to pull up–and decide which alert is most appropriate to deliver to the pilot.

ADIRU

Airbus has selected Honeywell and Northrop Grumman to provide air data inertial reference units (ADIRUs) for the A380. Honeywell plans to certify its ADIRU on the A320 and A340 series by early 2005, helping to reduce risk for the A380. The box can be swapped directly with systems on Airbus aircraft today. The new conduction-cooled system boasts a 50-fold improvement in processing power and improved algorithms tightly integrating GPS and IRS. A fleet-average MTBF of more than 40,000 hours is anticipated. The ADIRU runs on Honeywell’s DEOS operating system.

Northrop Grumman’s unit employs fiber optic gyros and micro electromechanical systems (MEMS)-based silicon accelerometers. The system will provide 22,500-hour meantime between unscheduled removal (MTBUR), says Jim Govostes, director of business development-commercial systems for Northrop Grumman’s Navigation Systems Division. Data throughput has increased 10-fold over the company’s prior model. The LTN-101E uses software- and hardware-implemented partitioning, and the core software runs on Green Hills Software’s Integrity commercial real-time operating system. The software, recently approved for use with a Level-A, DO-178B application, is also compliant with the ARINC 653 operating system specification. Northrop Grumman intends to certify its ADIRU on the A340 in 2005 and the A320 in 2006. The LTN-101E contains all the application software modules necessary for operation on all of these aircraft, assembling the software it needs via interrogation during system startup.

The LTN-101E’s Autonomous Integrity Monitored Extrapolation (AIME) algorithm tightly couples inertial and GPS measurements to limit inertial drift. The AIME technology allows 0.3 RNP to be guaranteed for 30 minutes on approach, in the event of GPS loss. Further, if the GPS signal were lost during a Category III GPS approach, the system guarantees Cat III approach capability for 2.5 minutes–from the outer marker to the ground.

Integrated Modular Avionics

The A380 integrated modular avionics architecture brings processing for numerous aircraft functions into modularized I/O and processing hardware, using a new ARINC 653-based operating system implemented by Thales. This approach standardizes hardware and software infrastructure, reducing acquisition costs and simplifying support. Systems suppliers will port their application software to these modules.

IMA consists of two main sets of components, the AFDX-based avionics data communication network and the IMA modules. Airbus expected to receive the first set of AFDX switches in March or April 2003. The IMA hardware modules will be provided by Thales and Airbus, using different hardware implementations. The first modules are expected to arrive in the second quarter of 2003. The IMA modules include a standard application programming interface (API), based on ARINC 653, and software drivers. (Airbus considers its API an improvement over what is provided in ARINC 653 and is working to standardize the refinements.)

Thales will provide 18 IMA modules: four for the landing gear, four for the fuel management system, four for cabin functions, four for air management, and two for electrical systems. The Airbus-provided modules will be used for input/output and to support the flight warning function, ATC communications function and the avionics communication router. Thales will ship 100 IMA modules to Airbus between June and August this year, says Alain Martres, the company’s A380 program director.

The API provides component obsolescence management, allowing hardware to be upgraded without affecting flight applications. This feature also allows system suppliers to develop applications independently from the hardware. The operating system also enforces partitions between application modules, so that multiple independent applications can run on the same hardware. One IMA hardware module, for example, hosts braking, steering and landing gear extraction/retraction functions, Martres says. Thales delivered the first version of the operating system to Airbus in December 2002. The company also has delivered more than 100 AFDX "end systems," the devices that interface the avionics modules to the AFDX backbone. (Rockwell Collins also supplies AFDX end systems.)

The IMA hardware architecture and operating system, however, do not extend to all functions. Flight-critical systems such as the AESS, FMS and ADIRU employ separate hardware assemblies and operating systems. Overall the A380 combines both integrated and federated avionics systems communicating over the high-speed bus.

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