The Avionics and Systems division of the Aerospatiale, specializing in on-board electronics, used the Alsys Ada environment to develop the Airbus A340's Flight Warning System (FWS).

The Ada Application

The FWS monitors the various systems of the aircraft, detects failures and dangerous flight conditions and generates the corresponding warnings. It provides the crew with operational assistance for both the normal and abnormal aircraft system configurations. It does this through visual and aural attention getting devices and through the two ECAM display units by means of warning messages and system synoptic diagrams. The FWS comprises two captain lighted pushbuttons (Master Caution and Master Warning), two First Officer lighted pushbuttons (Master Caution and Master Warning) and ECAM Control Panel (ECP) enabling the crew to perform actions such as:

• energizing and adjusting brightness of the ECAM displays units;
• manually presenting of system pages;
• recalling cleared warnings;
• clearing displayed messages and synoptic diagrams;
• testing take off configuration; and
• calling status pages.

Two computers, named Flight Warning Computers (FWC), send discrete data to lighted pushbuttons, audio data to the loudspeakers and warning messages to the warning and system display.

Ada Advantages

The Ada software performs the management and on screen composition of the various alarms. Originally chosen after a comparison with C and PL/M which proved that it provides the fastest execution speed to the application, Ada increasingly demonstrated its many other advantages during the development period. The engineering team was composed of ten people at the peak periods and developed 100,000 lines of code. Jerome Verzat, Project Manager, states, "Ada provides quality and safety by its intrinsic features, which makes the obtaining of certifications from official organizations much more easy than with other languages."

Ada's strong typing detects errors more easily in both initial and separate unit compilations. At the same time, the use of package mechanisms enabled substantial increase gain of productivity within the development team, significantly cutting the costs of development with regard to previous applications. Referring to the longer term strategy, Jerome Verzat declares, "Investing in Ada guarantees the best enhancement of the software for a long term strategy because its modularity and portability assure both easy inside improvements with complete adaptability to new technologies."

Based on a VAXstation, the application targets a proprietary CPU card with the Intel 80386 processor. The fact that the Alsys compiler is validated by official organizations was the key reason for its selection, because it answers the increasing requirements imposed by the certification tests.

"Our FWS system for the Airbus A330 is about to be certified and our company won't stop investing in Ada since it provides us with the quality that no other language can provide," concludes Jerome Verzat. Moreover, he is now investigating the opportunity of taking advantage of the upcoming Ada9X real time extensions in the development of new avionics projects.

Produced in cooperation with AdaIC, Ada Software Alliance, and ACM SIGAda. Thanks to Jerome Verzat from the Avionics and System Division of the Aerospatiale for presenting his experience with Alsys Ada.