|
Heightened attention to the potential effects of the change exists in both the media and among the traveling public, as commercial airplanes rely on computers for many functions. Boeing has surveyed its commercial airplane fleet and identified some nuisance flight deck effects that could occur for a few airborne systems. Upgrade programs are now in place to replace the affected systems and ensure operators uninterrupted service both during and after the date change.
Many computer systems use only two digits
to define the year, such as "98" for "1998." When the year changes from
1999 to 2000 (and beyond), applications, operating systems, microcode, databases,
processes, monitoring equipment, and so on may have logic or arithmetic
problems. The year "00" may appear in sequence before "99," for example,
or software may consider "00" to be invalid. To ensure uninterrupted service
for operators, a Boeing team assessed the effect of the Year 2000 (Y2K)
on airborne systems for all Boeing airplane models currently in production,
out of production, and in development. The assessment showed that a very
small number of airborne systems on Boeing airplanes and some immediate
support equipment will be affected by the Y2K date rollover.
The search for potential Y2K effects was restricted to systems with
embedded software that use a date, which made it possible to exclude systems
and components that do not contain embedded software. However, even a
simple system such as a clock or a communications radio control panel
often uses software, potentially making it susceptible to Y2K effects.
The approach Boeing used for airborne systems included supplier evaluation
and reporting results and providing upgrade paths for affected systems.
This approach was aligned with the company's goal to prepare computers
for the Y2K rollover a year early, by December 31, 1998.
Supplier Evaluations Results of Supplier Evaluations and Upgrade Paths AIRBORNE SYSTEMS WITH DATE EFFECTIVITY CHECKS. FLIGHT MANAGEMENT SYSTEM. Some FMSs offer an alert message to indicate an out-of-date NDB (NAV
DATA OUT OF DATE). This message is triggered when the NDB effectivity
does not match the clock date input when selected or at power-up or flight
completion on the ground. On a few systems, this message will be triggered
erroneously, even if the NDB is current. Because such
an erroneous message can delay dispatch or distract the flight crew, Boeing
considers it a nuisance for flight operations.
Figure 1 shows representative IDENT pages for
the second-to-last and last 28-day NDB cycles of 1999. The latter depicts
the /YY overflow and erroneous NAV DATA OUT OF DATE scratchpad message.
Boeing considers these Y2K issues significant because they generate
flight deck effects that are inconsistent with the company's "quiet, dark"
flight deck philosophy. However, no flight critical effects exist, and
safety of flight is not compromised. In addition, dispatch is still possible,
and full and normal functionality of the FMS is available. These flight
deck effects do not occur in the FMSs of the latest Boeing models, namely
the 777-200/ -300, 737-600/-700/-800, MD-11, and models under development
(717, 737-900, 757-300, 767-400, and MD-10).
The FMSs affected are those with one of two flight management computers:
Honeywell (for both Boeing- and Douglas- designed airplanes) and Smiths.
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 overflow. A
new software version, Load 14, which incorporates fixes to remove these
effects is available. (See "Communicating About the
Year 2000" for further information on service bulletins and other
communication with operators.) Operators should note that Load 12 and
subsequent versions require S242T102-552 hardware.
The 757 and 767 models with early 100K disk or early 200K systems exhibit
the IDENT page anomaly, which was rectified in the latest 200K versions.
Operators should note that due to parts obsolescence, Honeywell will not
support 100K disk-based FMCs beyond December 31, 1999. The 1 Megaword
PIP FMC versions on the 757 and 767 issue the erroneous NAV DATA OUT OF
DATE message; an upgrade is planned to fix this anomaly. Early clocks
installed on the 757 and 767 do not have date output capability. If the
date is not available, the NAV DATA OUT OF DATE is not displayed. Operators
of 757s and 767s may also choose to upgrade to the recently certified
Future Air Navigation System (FANS) FMC (Pegasus), which is Y2K-ready
and available. Service bulletins for the 757 and 767 FANS retrofit will
be issued upon operator request.
Douglas-designed models have Honeywell FMSs similar to those in Boeing-designed
models. All MD-80s and MD-90s (except MD-90s with the Pegasus FMS) use
a two-digit display of database year on the IDENT page, which will overflow
to /100, with an additional zero wrapped to the next line of the display.
The MD-11 has no Y2K effects. The Pegasus FMS under development for MD-11
has no Y2K effects and will be the basis for the FMS under development
for the 717 and MD-10 (DC-10 upgrade).
For the Smiths FMC, in software Update 7 (U7) and
beyond, the NAV DATA OUT OF DATE message will be erroneously generated
during the NDB cycle that begins in December 1999 and ends in January
2000. This transient flight deck effect has been rectified in Update U7.5/8.5
for 4 MCU systems in the 737-300/-400/-500 and in Update U10 for 4 MCU
systems in the 737-600/-700/-800.
Table 3 summarizes all Y2K effects for various
FMCs. Table 4 lists applicable service bulletins
and service letters to upgrade Y2K-affected FMCs. These service bulletins
and service letters address new FMC versions with operational enhancements
and software fixes in addition to Y2K fixes.
INERTIAL NAVIGATION SYSTEM (INS). Some DC-10 airplanes were fitted with the AINS-70 area navigation system,
and the ground support software for this system is susceptible to Y2K
problems. Rockwell-Collins has already informed AINS-70 operators that
it will not support the system after 1999.
GROUND-BASED SOFTWARE TOOL (GBST). ONBOARD MAINTENANCE SYSTEM (OMS). BUYER-FURNISHED EQUIPMENT (BFE). BFE includes systems purchased directly
by operators from suppliers and certified by Boeing installation on operators'
airplanes. Boeing will communicate to operators any information it obtains
on BFE systems.
POST-DELIVERY MODIFICATIONS TO BOEING AIRPLANES. Numerous after-market
modifications to Boeing airplanes are available and may be purchased from
various modification agencies and airlines. These modifications, usually
alterations made through the STC process, are not normally reviewed or
approved by Boeing. Modifications designed by parties other than Boeing
that are performed on Boeing airplanes after delivery may affect the applicability
of Boeing engineering, maintenance data, and spare parts. Operators should
contact the holder of each STC for additional information regarding Y2K.
Boeing will communicate to operators any Y2K information it obtains on
systems installed by STC.
Summary Certain airborne systems on some Boeing models (727, 737, 757, 767,
747, and DC-10) will have erroneous flight deck effects following rollover
to Y2K. Although most of these systems will continue to function as designed,
Boeing recommends that operators upgrade such affected systems. For the
MD-80 and MD-90, no upgrade is considered necessary, but if a change is
implemented for other reasons, it will include a Y2K upgrade and will
be made available to those operators who request it.
For More Information Forward-Looking Information Is Subject to Risk and Uncertainty |
return to top | Boeing Home | Commercial Copyright © The Boeing Company. All rights reserved. |