Integration of the Control Display Navigation Unit (CDNU) Into the EA-6B Block 89A Aircraft and its Impact on Navigation Operations

This thesis was to evaluate the attributes of the recent modification and installation of the Control Display Navigation Unit (CDNU) into the EA-6B aircraft. The author conducted multiple ground and flight test events during a three year evaluation of the EA-6B Block 89A aircraft.

The Block 89A modification included an embedded Global Positioning System (GPS)/ Inertial Navigation System (INS) (EGI), enhanced functionality with the recent GPS system modification, and the ability to control the navigation, weapon, and communication on one control panel. This modification was an attempt to replace a failing attitude system and also allow for additional capability. The testing performed included ILS and GPS approaches, holding, air navigation routes, low level military navigation routes, and tactical navigation. The EA-6B is currently not authorized to navigate with the GPS as the sole navigation (NAV) nor authorized to conduct GPS approaches. This evaluation revealed a need for a GPS navigation and approach authorization in the EA-6B. Funding should be started immediately to anticipate meeting the technology requirements once free flight is authorized in the US.

This thesis describes the navigation modes currently used in the EA-6B aircraft. The newest 89A upgrade demonstrates great advances in navigation ability with the addition of the EGI.

The CDNU as installed in the EA-6B Block 89A aircraft satisfies the FAA requirements of a flight management system (FMS). The CDNU also partially satisfies GPS certification requirements for both the FAA and DOD.

The requirement necessary to certify and utilize GPS as a primary navigation source to operate in the NAS not including approaches are RAIM or RAIM equivalent. The CDNU has a function known as EHE that uses an algorithm that was shown to be accurate enough to satisfy this requirement as long as it was used in the blended mode of operation.

GPS accuracy was excellent and pilot displays were easy to read and follow. The capability to execute non-precision approaches were demonstrated in the testing and with the addition of RAIM, an unalterable loadable approach, and an alert within the pilot’s primary field of view will allow GPS non-precision approach certification. RAIM capability is available with the GEM IV receivers. An unalterable approach is available with the addition of more memory in the CDNU. An alert is available by physically mounting a new warning light or by activating something on the EFIS displays.