AdaIC News Winter 1996


Boeing 777 Boeing 777 Soars
with Ada

On the 777's first flight, and in the year since, all the software-controlled electronic systems have worked perfectly together.

|Passing Tough Tests |Working Together - With Ada|
|Reusing Code, Meeting Deadlines |And Still More Reuse|

By Ann S. Eustice

Commercial aviation is changing -- the industry needs smaller planes to fly longer distances. At the same time, those planes have to meet the stringent national and international safety standards set down by the Federal Aviation Agency (FAA) and Europe's Joint Airworthiness Authorities (JAA).

As the Boeing 777 goes into service, Ada has been a critical factor in meeting those standards and winning clearance as soon as possible.

Passing tough tests

Boeing's 777 is a twin-engine aircraft, and has to meet the FAA's Extended Twin Operations (ETOPS) standards. The original ETOPS rule was drafted in 1953 to protect against the chance of dual unrelated engine failures. Unless a newly designed and produced aircraft has had at least three engines, it usually has had to wait sometimes four years before the FAA and the JAA would allow it to fly more than one hour from an airport. When a new twin-engine aircraft is veteran enough, it is allowed to be three hours away, which puts the world at its landing gear. Shortening the trial period would drastically increase Boeing's sales -- in what executives agreed in a Public Broadcasting Service (PBS) documentary is a "make or break" project for the company.

According to the Boeing executives interviewed by PBS, engines are now ten times more reliable, and the accident rate is 60 times better. (Since 1959, no airplane has suffered dual unrelated engine failures.)

Nonetheless, Boeing subjected the 777 to extensive testing. Ronald Ostrowski, director of Engineering, claims that the Boeing twinjet is already the most tested airplane in history. For more than a year before its maiden flight, Boeing tested the 777's avionics and flight-control systems' reliability around the clock in laboratories simulating flight.

The basic hardware of the 777's engines could be tested by their developer, Pratt & Whitney. But the engines' reliability and passing the ETOPS test period would be equally dependent on the quality of the software. And those outside systems in the 777 are programmed in Ada. On the maiden flight, with the Boeing Telemetry room in constant contact with the plane, the engines performed better than expected.

The 777 proved itself an ETOPS "veteran" on its first flight out -- becoming the first twin-engine plane to win FAA approval for "ETOPS out of the box."

What is happening on the 777 is also happening on smaller airplanes, such as turbo props. More reliable hardware and software are revolutionizing aviation. The systems in the cockpit talk to the other systems through the programming language -- and on such new airplanes as the Beechcraft 400A, the Learjet series, and some English jets, that language is Ada.

Sales for the Boeing 777 nationally and internationally are excellent. As of August 1995, Boeing had received 164 firm orders and 108 options.

Working together -- with Ada

On the 777's first flight, and in the year since, all the software-controlled electronic systems have worked perfectly together.

"Working Together" was, in fact, the project name Boeing chose in 1990 when it first introduced the idea of producing the 777. Ada would be instrumental in that working together, and the software to be written would come in from all over the country. Honeywell of Phoenix, Ariz., for instance, developed the cockpit's primary flight controls in two projects, the Airplane Information Management System (AIMS) and its Air Data/Inertial Reference System (ADIRS). Sundstrand of Rockport, Ill., created the 777's main, backup, and external electrical power systems. Rockwell of Cedar Rapids, Iowa, was another major subcontractor.

At first, some companies were cautious about switching to Ada. Honeywell approached the question by conducting an extensive study to gauge the benefits of Ada versus C. When the results were in, the company concluded that Ada's built-in safety features would translate into less time, expense, and concern spent on debugging the software.

Timing was also a factor: When Boeing specified that the systems had to be in Ada, Sundstrand Corp., was already six months into its part of the project. "We had to start all over again," Dwayne Teske, Program Manager for the 777's main electrical-generating system, said in a recent telephone interview. "But the project went really smoothly after that, so Ada had a lot of positives."

Reusing code, meeting deadlines

Sundstrand and Rockwell also joined the Ada bandwagon and have been on it ever since. Both companies have found themselves reusing Ada code and taking advantage of its portability in projects after they signed off on the Boeing 777 software.

Two new projects, for the Gulfstream V business jet and the Comanche helicopter, were able to integrate Sundstrand's library of common generic packages written in Ada for the 777.

In fact, the Sundstrand power systems' 80,000 lines of code were in themselves reused by 10 to 15 percent. The embedded software's small size proves that Ada is well-suited for projects under 100,000 lines of code, as well as for large efforts. The 777's Cabin Management System, for example, is a communications module mounted on the 777's seatbacks and offers passengers a variety of services; it is only 70,000 lines.

According to common logic, with suppliers like Sundstrand working for the first time in Ada and Honeywell adding a new target on top of a new language to the engineers' learning curve, the result should have been cost and schedule overruns. Instead, four and a half years after laying out the program, the 777's electrical power systems were on schedule. Boeing was able to turn on the power a full six months before the maiden flight.

And still more reuse

For Boeing, the bottom line is looking healthy -- in part because of reusable code. Software is driven by the same economic forces that drive demand for the 777 aircraft itself -- industry needs to do more with less, and to meet strict standards in doing so. Ada is a natural fit for those tasks, and with Ada reuse comes naturally. The code isn't "yesterday's work" -- it's money in the bank, an investment in the future.

According to Brian Pflug, engineering avionics software manager at Boeing, the ultimate value of Ada is in rapidly transferring the 777's code into the aircraft and architectures of the next millennium.

Please fasten your seatbelts -- we're about to take off.

[For those who would like to obtain a copy of the PBS documentary on the 777's first flight, covered from mainly the hardware point of view, the video is available for $19.98 from PBS, 800/828-4PBS.]


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