Guy Norris/Seattle
The year 2000 software nightmare scenario is like something from the 1951 science fiction classic The Day The Earth Stood Still in which an omnipotent alien paralyses the world by shutting down every electrically operated device for an hour.
If Boeing is right, nothing like this scale of disruption will occur as the world's aircraft computer-based systems move into the next century. The worst that can happen, claims Boeing, will be delayed dispatch or - in the case of an aircraft with an early inertial navigation system (INS) - pre-ßight procedures may not be able to be carried out.
"We started in 1993 to address the Y2K issue for airborne systems," says Boeing Commercial Airplane Group (BCAG) aircraft systems vice-president Tim Fehr. All Boeing airborne systems were evaluated to identify any possible defects or adverse impacts from "date-rollover" processing at midnight on 31 December, 1999.
The company's Airborne Systems Year 2000 Team study included all Boeing airliner models now under development, in production, or in use, including military derivatives. It also included Boeing-approved tools required for normal customer airlines' operation.
Part of Boeing's problem was knowing where to stop. Legally, it is obligatory that, for aircraft still under warranty, all Boeing-designed or created software will function regardless of the year. This helped limited the scope, as more than 80% of its aircraft software comes from suppliers. For the rest of the fleet, it "recommends" that airlines may incorporate Boeing service bulletins (SBs) to make the recommended software or hardware changes. "We are not in the practice of trying to police customers," says Fehr, who adds: "We only encourage all of the operators to take a serious look at all the modifications they've done."
The study also excluded any aircraft parts or components approved via supplemental type certificate without Boeing involvement, ground-based systems or test equipment, and satellites and other outside communications devices. Even with these limitations, the task was huge and involved conducting a comprehensive survey of 108 suppliers. Some survey responses to do with the cabin systems' area have yet to be completed, and the final report was expected to be finished by the third quarter of this year.
The survey asked each supplier for a list of the software functional areas that use date information, a list of the systems and line replaceable units that will be affected and the number of significant date digits used (eg, "1997", or just "97"). The survey also requested a description of the system effect of the date rollover, including the effect on maintenance functions and databases.
If only the maintenance/database areas were affected, it also asked for a description of the function and whether a date was used to sort or arrange data. It also asked whether the year "00" was sorted below "99". In other words, if "00" is the oldest data and never stored, is it always overwritten when included with "99" data?"
"We found no safety of flight issues, but in airlines we found operational issues," says Fehr, who adds that very little use of data, in general, was found to occur in airborne systems.
BIGGEST IMPACT
The biggest impacts have been identified in three on-board navigation data systems that use embedded databases. These have operational software loaded into them that either check or display the effectiveness of the date. "The key to that is some older FMCs [flight management computers] will give an indication that the navigation database is 'out of date', and the older Litton INS would do the same," says Fehr.
Uncorrected with new software, and possibly hardware, the FMC would generate a nuisance message that "may potentially delay dispatch or distract the flightcrew", says Boeing. "Aircraft with the INS would not be able to complete pre-flight procedures," it adds. The FMC-affected aircraft would still be able to dispatch, but the Litton-equipped aircraft "would not be allowed to go", adds Fehr.
The problem affects 747-400s, some 757s, 767s, MD-80s and MD-90s equipped with Honeywell FMCs. Smiths FMCs on 737-300/400/500s are also affected. The Honeywell FMC versions in the 747-400 issue an erroneous NAV DATA OUT OF DATE message and some also have the IDENT page/YY (year) overflow. This happens on some flight management systems (FMS) where the year is indicated by two digits (eg. /98), but, for the year 2000 and beyond, the field overflow is displayed as /111 or /100 with an additional zero wrapped to the next line of the display. Honeywell has developed a new software package, Load 14, which solves the problem.
The 757s and 767s with early FMCs exhibit an IDENT page anomaly, says Boeing and, although an upgrade is planned, many are expected to use the opportunity to upgrade to the recently certified Pegasus FMC. This is Y2K compliant and certified for Future Air Navigation System (FANS) operations. All MD-80s and most MD-90s, except the latest production versions with the Pegasus, are also affected, while the MD-11 has no Y2K effects. The Pegasus FMC is the basis for the system to be used on the 717-200 and MD-10.
The Smiths FMC with software Update 7 and beyond will show NAVDATA OUT OF DATE messages from December 1999 to the end of January 2000. An updated software load, Update 7.5 for 737-300/400s and -500s and Update U10 for Next Generation 737s, will ensure that the "transient flightdeck effect" is rectified, says Boeing.
Although not all Litton INSs are affected, the problems are generally found in some 727s, 737-200s, 747 "Classics" and DC-10s, and are classed as "significant" by Boeing. Most affected are Litton LTN-72RL and LTN-92 versions. Boeing has also discovered that some DC-10s fitted with the Rockwell Collins AINS-70 area navigation system, and the ground support software for the system, are susceptible to Y2K problems. However, like Honeywell with the early -100K disk-based FMCs on the 757/767, Collins has told operators that it will not support the system after 1999.
The survey also turned up other findings that primarily will affect Honeywell systems on the 777 if not corrected later in the next century. The first problem date is 2038 on the Honeywell maintenance terminal function, followed in 2060 with problems on the aircraft condition monitoring system. The Honeywell satellite communication system now in general use will have a date-related problem in 2089, while the 777's central maintenance computer would be in for problems in 2090, in the unlikely event that any would still be in operation.
Other problems were also unearthed with a Boeing-supplied ground-based support tool, hosted on Sun Microsystems SPARC2 and SPARC5 workstations. The tool is used to tailor the aircraft information management system functionality in the 777, and for FMS functionality in the Pegasus FMC on the 757 and 767.
GETTING READY
"We've gone out with service bulletins to all of the aircraft, and we're probably on our fourth update," Fehr says. Boeing has received many enquiries from airlines, he adds, noting that "some need to move on quickly". He warns that most of the more serious potential problems are at airports. "The aircraft are safe, but the infrastructure they count on could be more at risk."
Boeing's own giant internal infrastructure is under similar scrutiny from the Y2K team. "There are lots of internal situations where we are worried about the effects on continued production. We don't want to find problems with these in December 1999," says Fehr. Typical threatened systems range from vital computerised machine tools like the automated Gemcor wing riveters to the system controlling the exhaust temperature of the paint hangars, and even the elevators inside the buildings. "Any kind of environmental controller or power grid - anything that has a simple processor that checks a timetable for seasonal variations - they all need watching," says Fehr. "Of course, we are all anxious to make sure there are no problems with the computer that gets the pay cheques to the employees."
Source: Flight International
