The F-4E derives electrical power from a pair of AC generators driven by the J79 engines, a pair of AC to DC transformers, and a battery for electrical functions with the engines offline. In addition, the Phantom II can receive external electrical power from ground crew. The two generator arrangement, while normally working independently, includes a bus tie that can connect both buses together to draw power from a single generator in case of failure.

Generator Indicator Lights


Three warning indicators are found on the generator indicator panel: LH GEN OUT, RH GEN OUT, and BUS TIE OPEN. The respective GEN OUT warning will illuminate in the event the generator in question fails. The indication of BUS TIE OPEN is an acknowledgement that a single functioning generator is providing power to the entire aircraft. In the event of a generator failure, the Master Caution will also illuminate. However, in case both generators fail, no GEN OUT light will illuminate.

Generator Control Switches


A pair of Generator Control Switches are found on the right console, one for each engine. These three position switches - ON (Forward), OFF, ON External (Aft) - control the state of each respective generator. In the event of a possible generator failure, selecting OFF for the generator that is believed to be offline will cause the power bus to provide electricity from the remaining generator to the other half of the electrical system. The External On setting is used for ground handling purposes when connected to external power, and provides electric power to all instruments, except the CNI and the AFCS.

Instrument Ground Power Switch


Power from an external source to the instrument buses (115/200 volt ac, 28 volt ac, and 14 volt ac), can be provided by the Instrument Ground Power Switch (1) (if the generator switches are set to EXT ON), found on the right wall in the rear cockpit. Once external electrical power is disengaged or an engine generator comes online, it will switch off.

Bus System


The battery and generators power several buses which then route current to the relevant systems:

  • Left Main AC Bus
  • Right Main AC Bus
  • Instrument AC Bus
  • Warning Light AC Bus
  • Main DC Bus
  • Essential DC Bus
  • Armament DC Bus
  • Battery Bus

Circuit Breakers

From the buses, power is first routed through Circuit Breakers before they reach the actual systems.

💡 Due to engine limitations, CBs in the WSO cockpit are currently not accessible.

Most circuit breakers are placed in the WSO pit on either wall, with the exception of one panel in the pilot pit, housing breakers for the flight control surfaces and similar crucial systems.

Pilot Panel


Located on the right wall of the pilot cockpit, this panel contains seven circuit breakers responsible for flight control surfaces and other systems important for safe operation of the aircraft.

  • AIL Feel-Trim (1)
  • STAB Feel-Trim (2)
  • Speed Brake (3)
  • Landing Gear (4)
  • Flaps (5)
  • Trim Controls (6)
  • Rudder Trim (7)

Lighting Panel


Hidden behind a bundle of cables to the right of the telelight panel in the Pilot cockpit are two circuit breakers controlling lights.

The upper one (1) is responsible for powering the primary instrument lights, while the lower (2) circuit breaker powers all indicator and warning lights.

CB Panel 1

WSO CB Panel 1

Front section of right wall in WSO cockpit.

Has the circuit breakers for all stations, the armament and weapon system.

CB Panel 2

WSO CB Panel 2

Center section of right wall in WSO cockpit.

Mostly responsible for Engine and Hydraulics operation.

CB Panel 3

WSO CB Panel 3

Aft section of right wall in WSO cockpit.

Contains breakers for auxiliary functions, such as Anti-Icing or the Arresting Hook.

CB Panel 4

WSO CB Panel 4

Aft section of left wall in WSO cockpit.

Master controls of power coming through all buses, the flight computer and targeting pod.

CB Panel 7

WSO CB Panel 7

Next to the right rudder pedal in WSO cockpit.

Hidden behind a cover, this panel houses all breakers for the ECM and Jamming equipment.

Failures and Emergency Power Distribution

In the event of damage to the Airplane and loss of either the left and/or right generator, as well as the Main 28 Volt DC Bus there are several different systems that are inoperative for the respective bus.

Left Hand Generator Out - Bus Tie Open

If the left-hand generator stops working the following systems won't work:

Critical SystemsNon-Critical Systems
Anti-Ice SystemAN/ARW 77 (Used to fire AGM-12 Bullpup)
Anti-Skid SystemAnti-Collision Light (one filament)
Afterburner IgnitionDSCG
INS HeaterECM Pods
Landing lightEquipment cooling (e.g. Pave Spike)
Fuselage lights
Front Cockpit console lights
Front Cockpit red instrument floodlights (DIM)
Lead Computing Optical Sight
Left-hand 28V Transformer
Left-hand fuel boost pump
Left-hand missile firing
Left-hand missile power
Left-hand transformer rectifier
No. 4 Electrical fuel transfer pump
Nose gun
Radar Scope Camera
Red console floodlights
Right-hand missile power
Seat adjust
AGM-45 Shrike guidance
Target designator (Pave Spike)
Utility light
Utility Power AC
Wing and Tail light DIM
WRCS Power

Right Hand Generator Out - Bus Tie Open

If the right-hand generator stops working the following systems do not work:

Critical SystemsNon-Critical Systems
Airspeed Pitot HeaterADF
AOA Probe HeaterAileron feel trim
Bellmouth Pitot HeaterAileron rudder interconnect
Cockpit heat and ventingALR-46 Radar Warning System
Fuel quantity indicatorAltitude Encoder
IFFAnti-Collision light (one filament)
Rear cockpit ci heading pointerAPR-36/37 Radar Receiver
TACANAPX 80 Air-to-Air IFF
VOR: Bearing PointersArmament power
Auxiliary receiver
ECM Pods
Formation lights
Front cockpit instrument lights
Gunsight Camera
In-Flight-Refuel (IFR) receptacle floodlights
Left Engine ramp control
No.6 Electric fuel transfer pump
Oxygen Gage
Radar altimeter
Right Engine ramp control
Right-hand 28V transformer
Right-hand fuel boost pump
Right-hand transformer rectifier
Stability augmentation
Taxi light
Windshield temp sensing
Wing and Tail Light BRT

Main 28 Volt DC Bus Out

If the Main 28 Volt DC Bus stops working the following systems do not work:

Critical SystemsNon-Critical Systems
Anti-SkidACM IN-RANGE and SHOOT lights
Bus Tie Relay (BUS TIE OPEN light ON)ADF
Cockpit heat and ventingAileron Rudder Interconnect
Internal wing fuel dumpAirborne Video Tape Recorder (AVTR)
Landing and Taxi lightsALE-40 Countermeasure Dispenser
Nose Wheel SteeringAltimeter Vibrator
TACANAPR-36/37 Radar Receiver
Turn & Slip Indicator (Rear Cockpit)APX 80 A/A IFF
Arresting Hook (only the up operation)
AUX Air doors
AUX receiver
Conventional Weapons Release
Combat Documentation Cameras
ECM Control
ECM Pods
Engine Variable Bellmouth
Equipment cooling control
Fuselage, Anti-Collision and Tail lights
Gunsight Camera
Lead Computing Optical Sight
Left-hand fuel boost pump
Missile firing
No.4 Electrical fuel transfer pump
No.6 Electrical fuel transfer pump
Nose Gun
Pneumatic compressor
Radar Altimeter
Rain Removal
Radar Scope Camera
Right-hand Fuel boost pump
Rudder Trim/Bellmouth control
Speed brake
Special Weapons Centerline Interlock Arm
Station select and Station select lights
Stabilator Position indicator
Target Designator (Pave Spike)
Utility power
VGH Recorder Power
Walleye indent power
Warning lights (DIM)
WRCS Power

Battery Power Only

If only Battery Power is available the following systems will still work:

Critical SystemsNon-Critical Systems
AOA IndicatorAll Stores EMER jettison
EGT IndicatorsAOA Aural Tone Generator
Ejection LightFuel Control
EMER Attitude IndicatorFuel Valve Power
Engine Fire and Overheat Detection (Test Functions)Front Cockpit Instrument Floodlights (BRT)
External Wing Fuel transfer (Control)Guard Receiver
Flaps/Slats controlKY-28
Flaps/Slats Position IndicatorMissile Fairing
Fuel Quantity IndicatorMissile Jettison
In-Flight-RefuelingNozzle Position Indicator
ILS: CDI, Glide Slope Indicators, Audio, Marker BeaconOutboard Station jettison
IntercomSpecial Weapons Centerline Interlock Safe
Internal Wing Fuel transfer (Control)Special Weapons Unlock
Landing Gear ControlTrim Control
Landing Gear Position Indicator
Left and Right Main Ignition
Stabilator Feel Trim
VOR: CDI, TO-From and Audio
White Flood light