Boeing 747 navigation and avionics
Classic 747s flew with three Litton LTN-72 inertial navigation units used as primary references. The 747-400 moved to twin Flight Management Computers driving glass PFD/NDs and EICAS displays, with navigation radios integrated through the FMS.
Navigation on the 747 traces the industry’s digital shift: the classic’s dark-panelled triple inertial units gave way to the 747-400’s dual Flight Management Computers and six glass display units.
| Key facts | |
|---|---|
| Classic 747 | Three Litton LTN-72 inertial navigation units (INS) |
| 747-400 | Twin FMCs, inertial reference units, six display units |
| Displays | Captain’s and F/O’s PFDs and NDs, plus main and auxiliary EICAS |
| Integration | VOR/DME/ILS radios, air data and fuel systems all feed the FMS |
For classic 747s, three four-gimbal, all-attitude inertial platforms dead-reckoned the position across oceans, cross-checked against VOR/DME near land. The crew managed the navigation problem around a nav table.
The 747-400 folded all of that into software. Its dual Flight Management Computers use five processors each and integrate the air-data sensors, crew inputs, navigation radios, engine and fuel systems and inertial reference to provide flight control command, navigation, thrust management, map display and performance optimisation, all reached through a CDU keypad.
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