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Saturday, July 1, 2006

A400M Advances: Taking Off From the A380

Charlotte Adams

Avionics development for Europe's military airlifter is accelerating. While the A400M baselines much Airbus A380 technology, it adds new flight and mission systems.

The long-awaited European military transport aircraft is heading through a period of intense avionics activity, as initial prototypes are matured and integrated into larger test benches. The A400M "takes off" from its cousin, the Airbus A380 superjumbo passenger jet. But the military aircraft adds all-new systems and uses the baseline technology in a completely different way.

The cockpits of the Airbus airliner and the planned A400M look strikingly similar. Both splash large liquid crystal displays (LCDs) across the front panel and feature equally large flight and mission management interfaces in the center pedestal. Both use the latest trackball devices to move the cursor between cockpit systems and can include LCD-based head-up displays (HUDs).

But the philosophy behind the military cockpit is totally different, says Philippe Benquet, A400M program director for Thales Avionics, which provides the displays and HUDs for both aircraft. The A400M's flight deck reflects Thales' experience with combat aircraft, he says. "Everything related to the short-term is on the HUD." That includes not only piloting information but also tactical information about threats, air drop guidance, low-level flight (LLF) and air-to-air refueling.

HUD as PFD

The A400M's HUD will be certified as a primary flight display (PFD). The A380's HUD, by contrast, is an option for customers, but is not included in the basic aircraft certification and will not be a primary flight instrument. This means that during high-workload procedures such as low-level flight, A400M pilots will rely on the HUD for flying the aircraft. Since the traditional PFDs won't be needed at such times, the front panel displays can be dedicated to medium-term information, such as the tactical situation, moving map and weather radar, or longer-term information such as navigation, optimizing situational awareness.

The HUD will be able to display video from the Thales forward-looking infrared (FLIR) system for night and bad-weather flight. Although the HUD computers for the A400M and A380 are identical, the mechanical and optical elements are customized for compatibility with military night vision goggles (NVGs) and helmets. All flight deck lighting is NVG-compatible.

The display system is designed for flexibility. The eight presentations are essentially interchangeable and reconfigurable. In the planned configuration, however, the two center units in the main panel are dedicated to crew alerting and engine/system monitoring. Although the two head-down displays (HDDs) in the pedestal can present any format, they normally are used for controlling the flight management system (FMS) and military mission management system (M-MMS), an all-new element on the A400M. A ninth HDD can be added on the rear pedestal to provide a third crew station.

Current Status

Airbus, which manages avionics development and integration under a subcontract to its military subsidiary, has assembled early prototypes for assessment on dedicated test benches. These platforms simulate the environment in which the systems will operate and stimulate them with appropriate signals, says Sergio Llamazares, head of A400M systems engineering for the Airbus Central Program Office in Toulouse, France. So far, the program office has received all prototype displays and control panels, HUDs and standby instruments, as well as the first version of the FMS, communications equipment and more than 40 integrated modular avionics (IMA) modules.

In the third quarter of 2006 Airbus plans to finalize the "Class 2" cockpit mockup. The Class 2 mockup uses the real front faces of the control panels and displays (but not the embedded processors) in order to validate the ergonomic aspects--the "touch and feel"--of the control and display system (CDS) and the cockpit lighting. A parallel cockpit assessment uses the real processors to validate display functions.

Based on feedback from these initial tests, suppliers will develop more mature prototypes, which will be integrated into a bigger test bench, known as "Aircraft 0." Aircraft 0 will combine the "iron bird" test bench and the main avionics test bench. The iron bird is used to verify the flight control, hydraulic and electrical systems.

Airbus expects to receive more advanced prototypes later this year. The "first flight" of Aircraft 0 is planned for the second quarter of 2007, when electrical power will be switched on. The real aircraft's first flight is expected in early 2008 in a configuration including all basic mission systems. Commercial certification and first deliveries are planned for the second half of 2009.

The military transport will feature eight 6-by-8-inch LCDs identical in technology to the A380's but ruggedized for the operating enviornment. Supplied by Thales Avionics, the CDS includes six displays in the main instrument panel and two in the pedestal. (The A380 deploys five displays in the front panel and three in the pedestal.)

An Airbus report on the A400M lists numerous formats that pilots can select for presentation on the HDDs. These include the PFD, navigation display, flight management display, communication management, surveillance management, engine and warning display, system display, tactical and situation management display, digital map, video, and give-and-take. (The give-and-take format is associated with the A400M's air-to-air refueling function as either a provider or receiver of fuel.) The system display also includes a "mailbox" for civil air traffic management and tactical military data link messages. The multifunctional information distribution system, or MIDS tactical data link, which includes Link 16, will be optional equipage. MIDS is used to exchange information such as flight paths, targets, position, status and commands between aircraft.

A400M pilots will use the same type of point-and-click, cursor control device and multipurpose keyboard that A380 pilots will have to interact with the displays. But military pilots will have a greater degree of interactivity to help them manage their increased workload, Llamazares says. The inclusion of military systems has more than tripled the number of display pages on the A400M vs. the A380, Benquet says.

Just as presentations can be moved from one location in the cockpit to another, information from one application can be overlaid on another. Navigation and tactical information can be superimposed on the map display, for example, and threat icons can be overlaid on the weather radar. Likewise navigation data can be added to the tactical display. The tactical display shows items such as missile sites, avoidance zones and drop zones. It draws information from the defensive aids subsystem (DASS), the military data link, and a threat database updated before each mission. Pilots can access additional information about threats by selecting icons on the display. The flight crew also can modify the threat data, as additional information becomes available, and pass the information to other aircraft over Link 16.

Thales also supplies two HUDs per aircraft for the presentation of critical information during demanding procedures such as takeoff and landing at undeveloped airstrips and during air drops, refueling and low-level flight operations. According to Airbus, the HUD displays parameters such as pitch and roll; heading; actual and potential flight path angle track; selected and actual speed and altitude; radio altitude; dropping guidance; landing aids; and high-priority messages relating to threats, decoys, warning and terrain. IR-based enhanced vision imagery is available for operations at night and in poor weather conditions. IR video can be fed from the FLIR sensor into the head-up, as well as head-down displays.

Navigation

The aircraft will use military GPS sensors with anti-jamming capability, inertials and air data systems as its main means of navigation. These are integrated into three computers known as GADIRUs (GPS, Air Data and Inertial Reference Units). The automatically tuned navaid suite also includes: VOR, DME, tactical air navigation (TACAN), automatic direction finding, and a multimode receiver with ILS, microwave landing system (MLS) and commercial GPS sensors.

Honeywell is adapting its integrated surveillance system, known as the aircraft environment surveillance system (AESS), for the A400M. The AESS radar has the same basic configuration, performance and technology as Honeywell's commercial RDR-4000, used on the A380. Honeywell notes, however, that in the A400M the radar processor is integrated in the AESS central processing unit. Mode S responses will be supplied through an external identification, friend or foe (IFF) system, according to Llamazares. The integrated surveillance system also will include Honeywell's enhanced ground proximity warning system and traffic alert collision avoidance system (EGPWS/TCAS).

This baseline radar provides standard turbulence and windshear detection, as well as ground mapping. Buyers, however, will have the option to substitute a military-specific radar. Airbus originally had planned to use a Northrop Grumman radar as the military option but ultimately decided against it. Commercial reasons precluded a final agreement, Llamazares says.

At press time, Airbus was finalizing an arrangement with Honeywell to supply a modified version of the weather radar, including all civil functions, as well as enhanced power management and signal processing. Airbus expects that Honeywell will modify the baseline radar to add a dedicated "military mission radar processor," developed by Honeywell and EADS Germany. This change, according to Llamazares, is designed to "bring all of the information out of the signal for better accuracy and resolution" in both the ground mapping mode and the air-to-air detection mode. The UK, Germany,Turkey and Belgium have selected the military radar option.

Flight Management

Airbus opted for a new FMS from Thales on the A400M, preferring a European supplier for this core system. Although the equipment performs the classical civilian FMS functions, it has been enhanced and greatly modified for military operations, says Llamazares. Its main military function is to support low-level flight, he says, although it also plays a role in air cargo delivery, air-to-air refueling, and search-and-rescue operations.

The basic low-level flight software is developed to the stringent DO-178B, Level A, standard, according to Thales. In this regime the FMS relies on the accuracy of the military embedded GPS/inertial systems. At this stage of development, Thales is focusing more on the commercial core functions. Implementation of military navigation functions will start at the end of 2006.

The company has developed flight management systems for helicopters and collaborated with Smiths Aerospace to produce the FMS for the Airbus A320, 330 and 340, says Benquet. Thales intends that the core technology will be competitive commercially on aircraft such as the A350. The benefit for the A400M will be that "all the logistics and ferry missions in international airspace will be straightforward for this aircraft," he adds.

The key feature of the FMS is its adaptability, based on an innovative requirements process and software architecture. The system will have to evolve in order to keep up with air traffic control regulations, military requirements and the mission choices of individual nations. It took a year for Thales to define this flexible software architecture.

Thales has delivered production-quality flight management computer hardware, based on IMA modules. The FMS software will be developed iteratively, in eight versions, between June 2006 and 2009, Benquet says. Thales expected to deliver the first version in June 2006 and the second version later in the year. The third iteration is scheduled for delivery in 2007, in time for the aircraft's first flight.

The FMS interface is fully interactive via trackball and keyboard. Using the Thales-supplied cursor control device--the equivalent of an aircraft computer mouse--the pilot can insert a new waypoint from the digital map in a few clicks, modifying the flight plan almost instantly, Benquet claims.

In partnership with Diehl and Airbus, Thales has developed IMA hardware. The modules are virtually the same as those on the A380 but have been requalified to meet military environmental requirements, according to Airbus. Thales and Diehl provide the modules for cabin pressure, air/ventilation and smoke detection; electrical load management, circuit breaker monitoring and power distribution; fuel, weight and balance, and air-to-air refueling; and landing gear and braking. Airbus provides the modules for flight control and avionics communications functions.

Military Systems

The M-MMS is designed by EADS Defense Electronics (DE) in Germany, supported by EADS CASA in Spain. The idea, says Llamazares, is to have FMS-type control over the military side, managing the Mil-Std-1553 data bus and separating military flight management tasks from classical civilian functions. The M-MMS uses two dual-redundant computers.

The M-MMS has communications management, cargo handling, fuel management and tactical ground collision avoidance functions. It manages the military radios, including autotuning, emissions control and frequency tables. Internally, the M-MMS serves as a data communications gateway between the military systems on the 1-Mbit/s 1553 bus and the A380-derived avionics connected over the avionics full-duplex switched (AFDX) Ethernet network. (AFDX on the A400M runs at two speeds: 100-Mbits/s and 10-Mbits/s.)

The new system translates between the AFDX and 1553 protocols. This enables the crew to control the radios through flight deck interfaces using AFDX. The M-MMS also calculates the weight and center of gravity of the cargo load, which it passes to the FMS as a basis for calculating total aircraft weight. It optimizes cargo loading and unloading plans, drawing from a cargo loads database. It also optimizes air delivery, calculating the optimal release point and communicating the information to the FMS for presentation to the flight crew. This calculation is based on data such as altitude, weight, wind direction and estimated parachute drag.

Tactical situation management is another M-MMS function. The system receives data from the aircraft self-protection systems and passes this data to the displays. It can provide tactical information received over Link 16 to the tactical situation display. The M-MMS also manages the threat database and makes that data available on the displays. And it records mission data for later use by the mission planning/data retrieval system.

Pilots will use the FMS for planning low-level flight segments. In such operations, the M-MMS verifies altitude and other information passed from the FMS against a high-resolution digital terrain elevation database.

M-MMS also manages the tactical ground collision avoidance system (T-GCAS), which alerts the flight crew if a ground collision is imminent. T-GCAS uses the high-resolution digital terrain elevation database, navigation sources and aircraft configuration and performance data to determine the flight path required to avoid obstacles and terrain. Although T-GCAS is optional, it has been selected for all of the aircraft on order to date, Llamazares says.

Low-Level Flight

The A400M will offer customers a choice between levels of low-level flight capability. The standard function correlates the aircraft's position, as calculated by the military GPS/IRS system and passed to the FMS, with a digital terrain elevation database managed by the M-MMS. The FMS provides the flight path and the M-MMS checks the path against the database to ensure sufficient clearance. The M-MMS then provides this information to the FMS and flight control computer to guide the aircraft along the flight path.

An optional terrain masking low-level flight (TMLLF) system, requiring a dedicated processor, has been selected by the German government. According to Airbus, the TMLLF requires no inputs from ground-based navaids or forward emitting sensors. The TMLLF and the basic LLF system allow the same minimum flight altitudes, but the TMLLF, among other features, includes automatic route planning. This automation takes into account threat and terrain information, using navigation sensors and terrain databases.

Another element that can enhance LLF and TMLLF operation is the terrain referenced navigation system (TRNS). According to Airbus, the optional TRNS can generate autonomous 3D position data independently of GPS, whose signals can be jammed or blocked by terrain in low-level operations.

The TMLLF system leverages improved processing and tactical situation presentation, compared with the basic configuration of the aircraft, according to literature published by Airbus majority owner, EADS. In addition, TMLLF relies on "a consistent process chain that builds on [these enhancements] and extends from route planning through to steering the aircraft along its [optimal] flight path." TMLLF presents hazardous zones and safe routes on a digital terrain awareness display.

The TMLLF also features a more powerful flight path capability. It "allows the use of a kind-of curvilinear flight plan," with legs as short as 50 meters (164 feet), Llamazares says. This enables aircraft to take benefit from the terrain, he says, masking them from potential or known threats. The system does not radiate, he stresses. "You use a terrain database. You use position coming from the IRS [inertial reference systems], GPS and air data sensors. It's passive." The TMLLF system takes the position of the aircraft from the navigation sensors and compares this with a specific terrain database in order to modify the flight plan to exploit the terrain.

The basic defensive aids subsystem, DASS, includes three systems: radar warning receiver, missile warning system (passive element) and expendables dispensing system. The suite can be upgraded with four additional systems: the laser warning receiver, directed energy countermeasures, towed radar decoy and missile warning system (active).

The DASS requires a defensive aids computer (DAC) for programming individual missions, including adapting and tuning the system to new threats. According to Airbus, this computer manages data communication, harmonizes threat warning data, coordinates countermeasures responses and manages radio frequency interoperability.

EADS Defense Electronics and Thales will provide the IR-based missile warning system-passive element, which detects the rocket plume of an approaching missile. It can automatically trigger the launch of decoys and, when required, provide alignment information to the IR countermeasures system to attack the missile seeker. An IR countermeasures system supplier has not yet been chosen, but Airbus is understood to want a system that can not just blind the seeker, but destroy it with a precisely aimed, high-energy laser shot.



Selected A400M Avionics Systems

Communications

Radios :
HF-Rockwell Collins
VHF and UHF-Rohde & Schwarz
Selcal (selective call)-Tecnobit
Inmarsat satcom (optional)-Rockwell Collins

Audio:
Audio management system-Tecnobit
Wireless intercom-Tecnobit
Cockpit voice recorder-L-3 Communications
Passenger address system-TEAM

Emergency locator transmitter system -HR Smith

Coms security- Government-furnished equipment

Data Links:
MIDS (optional)-Tecnobit and
VHF data radio-Rockwell Collins

Internal Coms:
AFDX switches and router-Rockwell Collins
AFDX end systems-Thales

Identification: IFF-Indra

Surveillance

Weather radar -Honeywell

Military radar (optional)-Honeywell (likely)

TCAS- Honeywell

EGPWS- Honeywell

Enhanced vision system (optional)-with FLIR-Thales

Tactical ground collision avoidance system (optional)-EADS DE

Navigation

3 GPS (mil.)/Air Data/Inertial Reference Units (GADIRUs) -Sagem

Navaids with autotuning:
VOR, DME, ADF-Rockwell Collins
Tacan-Thales Communications

Multimode receiver -Thales (with ILS, microwave landing system and two civil GPS receivers)

Two radar altimeters- Rockwell Collins

Digital terrain referenced navigation (optional)-EADS DE

Terrain masking low-level flight -EADS Military Aircraft

Flight/Mission Management

Two FMS computers -Thales

Two M-MMS computers -EADS DE, with CASA

Displays

Two foldable, wide-angle HUDs -Thales

Eight 6-by-8-inch head-down displays , including two KCCU (keyboard and cursor control devices)-Thales

KCCU, display and controls for a third crew station (optional)-Thales

Defensive Aids Subsystem

Defensive Aids Computer- EADS DE

Radar warning receiver- Indra

Missile warning system (passive element)-EADS DE and Thales

Missile warning system (active element)-no supplier

Expendables dispensing system- MBDA

Directed energy countermeasures- no supplier

Laser warning receiver- no supplier

Towed radar decoy- no supplier

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