Factual Information 2015:Appendix 1.6E/1.6E.14
This page contains an extract from MH370/01/15 Factual Information which accompanied the (first) Interim Statement released by The Malaysian ICAO Annex 13 Safety Investigation Team for MH370 on 8th March 2015.
Navigation systems include Global Positioning System (GPS), Air Data Inertial Reference System (ADIRS), Very High Frequency Omni Range (VOR), Distance Measuring Equipment (DME), Instrument Landing System (ILS), Automatic Direction Finder (ADF), Weather Radar, and the Flight Management System (FMS).
1.6E.14.1 Global Positioning System (GPS)
Left and right GPS receivers are independent and supply very accurate position data to the FMC. GPS tuning is automatic. If the Air Data Inertial Reference Unit (ADIRU) becomes inoperative during flight, the EICAS displays the message NAV ADIRU INERTIAL and the FMC uses only GPS data to navigate.
1.6E.14.2 Inertial System
The Air Data Inertial Reference System (ADIRS) calculates aircraft altitude, airspeed, attitude, heading, and position data for the displays, flight management system, flight controls, engine controls, and other systems. The major components of ADIRS are the Air Data Inertial Reference Unit (ADIRU), Secondary Attitude and Air Data Reference Unit (SAARU), and air data modules. The ADIRU supplies primary flight data, inertial reference, and air data. The ADIRU is fault–tolerant and fully redundant. The SAARU is a secondary source of critical flight data for displays, flight control systems, and other systems. If the ADIRU fails, the SAARU automatically supplies attitude, heading, and air data. SAARU heading must be manually set to the standby compass magnetic heading periodically. The ADIRU and SAARU receive air data from the same three sources. The ADIRU and SAARU validate the air data before it may be used for navigation. The three air data sources are the left, centre, and right pitot and static systems.
- a) Automatic Direction Finding (ADF)
- Two ADF systems are installed. Either ADF can be manually tuned from the left or right CDU on the NAV RADIO page.
- b) Very High Frequency Omni Range (VOR)
- Two VOR receivers are usually tuned by the FMC but, can be tuned manually by the crew. The tuned VORs display on the ND and may be used for position updates.
- c) Distance Measuring Equipment (DME)
- Two DME systems are installed. The DMEs are usually tuned by the FMC, but may be tuned manually.
- d) Instrument Landing System (ILS)
- Three ILS receivers are installed. They are usually tuned by the FMC, but can be tuned manually on the NAV RADIO page.
1.6E.14.4 Weather Radar
The weather radar system consists of receiver–transmitter unit, antenna, and control panel. Radar returns display on the Navigation Display (ND). The EFIS control panel weather radar (WXR) map switch controls power to the transmitter/receiver and controls the weather radar display on the ND.
1.6E.14.5 Flight Management System (FMS)
The FMS aids the flight crew with navigation, in–flight performance optimisation, automatic fuel monitoring, and flight deck displays. Automatic flight functions manage the aircraft lateral flight path (LNAV) and vertical flight path (VNAV). The displays include a map for aircraft orientation and command markers on the airspeed, altitude, and thrust indicators to help in flying efficient profiles. The flight crew enters the applicable route and flight data into the CDUs. The FMS then uses the navigation database, aircraft position, and supporting system data to calculate commands for manual and automatic flight path control. The FMS tunes the navigation radios and sets courses. The FMS navigation database supplies the necessary data to fly routes, SIDs, STARs, holding patterns, and procedure turns. Cruise altitudes and crossing altitude restrictions are used to calculate VNAV commands. Lateral offsets from the programmed route can be calculated and commanded.
The basis of the flight management system is the flight management computer function. Under normal conditions, one FMC accomplishes the flight management tasks while the other FMC monitors. The second FMC is ready to replace the first FMC if system faults occur. The FMC uses flight crew–entered flight plan data, aircraft systems data, and data from the FMC navigation database to calculate aircraft present position and pitch, roll, and thrust commands necessary to fly an optimum flight profile. The FMC sends these commands to the autothrottle, autopilot, and flight director. Map and route data are sent to the NDs. The EFIS control panels select the necessary data for the ND. The mode control panel selects the autothrottle, autopilot, and flight director operating modes.
Source: Malaysian ICAO Annex 13 Safety Investigation Team for MH370, 8 March 2015, Factual Information MH370/01/15
The Factual Information was updated in 2018 by the Safety Investigation Report MH370/01/2018 which added new content but did not include all of the previous data.