EICAS

Engine Indication and Crew Alerting System

Annotated E-10 / E-11 EICAS mock-up showing split bow/aft exhaust bars and RCS indications. Main-engine bars and RCS arrows show exhaust flow; vertical + / − signs show body-force direction. Readings are illustrative, not a flight screenshot or a performance specification.

EICAS is an acronym for Engine Indication and Crew Alerting System.
One interlinked system that informs the crew about aircraft operation and warnings about abnormal settings or situations.

The Engine Indication shows normal operational information such as:

• Fuel available
• Thrust output

Additional information can be found depending on the model:

• Landing gear
• Pitch trim
• Flap settings

Legacy engine indications

On displays with the original single-ended thrust bars, including the T-19, the box above the engine shows an amber "REV" when reverse is selected. See the annotated legacy EICAS layout.

E-10, E-11 and A-4 split-flow indications

On the E-10, E-11 and A-4 split-flow displays, each engine bar grows outward from a central white datum. The upper half shows exhaust from the bow outlet; the lower half shows exhaust from the aft outlet. These are exhaust directions, not directions of aircraft motion: aft exhaust produces forward thrust, while bow exhaust produces reverse thrust.

The number beside each half is actual outlet output as a percentage of its own rating. Each half has an independent 0-100% scale. Both wing-engine halves can be filled during VTOL; two 100% readings do not mean 200% net axial thrust or 200% vertical lift. The bars report outlet output before its force is resolved into axial and vertical components. Moving chevrons stay inside the filled area and follow the exhaust direction. Remaining flow continues to be indicated during spool-down after the thrust request is released.

On the E-10 and E-11, the engine boxes identify ENG1 (left), ENG2 (tail) and ENG3 (right). On the A-4, ENG1 is the left engine and ENG2 is the right engine; both use the VTOL bars, arranged side by side without an aircraft background. These displays use the following mode labels:

• FWD / REV: aft-only or bow-only exhaust with the nozzles in their axial position. These are green normal-operation indications.
• MIX: both axial outlets have flow.
• TRANS: wing nozzles between the axial and VTOL positions; shown in amber.
• VTOL: wing nozzles in their VTOL position. Read the two percentages for actual flow; VTOL alone does not mean that thrust is being produced.
• IDLE / OFF: zero outlet flow with propulsion powered or unpowered, respectively.
• FAIL: the engine is failed; shown in red.
• DATA: valid propulsion data is unavailable; shown in amber with dashes in place of outlet percentages. Do not read this as zero thrust.

The E-10/E-11 tail engine remains axial during VTOL. Its bar shows actual tail thrust, including thrust allocated to balance axial force from the wing engines. The A-4 has two tilting engines and no tail engine. During atmospheric flight, ascent, suborbital coast, orbit and re-entry, the bars continue to show actual main-engine outlet flow; the presence of a bar does not mean VTOL is permitted in that flight regime. These bars do not display RCS activity. Landing-gear indications remain separate.

E-10 and E-11 RCS indications

The E-10 and E-11 show RCS activity on the aircraft outline, separately from the main-engine bars and landing gear. The four circular indicators represent vertical RCS groups at the front and rear hull shoulders. Lateral arrows appear beside the front and rear groups. The two forward arrows and the two aft arrows near the tail represent the shared fore/aft RCS indication; each pair repeats the same activity.

Indication	Meaning
Cyan + inside a ring	RCS force toward the top of the aircraft (body up), from underside exhaust.
Cyan − inside a ring	RCS force toward the underside of the aircraft (body down), from topside exhaust.
Cyan arrow	The emitting outlet and exhaust direction. Left-side arrows mean rightward force; right-side arrows mean leftward force. Aft arrows mean forward force; bow arrows mean reverse force.
Filled portion of the outer ring	Delivered output on the common 80 kN-per-nozzle scale; a full ring means 80 kN from that nozzle.
Gray outline, with no + or −	Output is at or below the 2% display threshold; small stabilizing corrections may still be present.
Amber RCS DATA	Valid RCS indication data is unavailable. Do not interpret this as zero thrust.

Cyan arrows, circle signs and cyan ring fill appear only when the magnitude of that group's indicated output exceeds 2%. At or below 2%, the outlines remain gray and the circles have no + or −. Above the threshold, ring fill shows the original output percentage without rescaling. This display threshold does not change RCS thrust or automatic stabilization.

Directions are relative to the aircraft, not the horizon. Both RCS arrows and the animated main-engine bars indicate exhaust flow. Vertical + / − signs indicate force on the aircraft. A pitch or roll correction can light opposite signs at different hull groups without translating the aircraft. The indications follow RCS activity under manual control, TVM and DOR, including atmospheric and orbital operation; they do not announce whether main-engine VTOL is available.

For a nose-up correction, the front circles show + (underside exhaust) and the rear circles show − (topside exhaust). For a right roll, the left circles show + and the right circles show −. A nose-right yaw correction lights the front-left and rear-right lateral arrows. The opposite corrections reverse these indications. Each of the four circles represents an opposed upper/lower pair; the eight vertical directions are not eight independent channels.

The E-10, E-11 and W-6 use the same 80 kN RCS nozzle rating. The indications show delivered output after power, health and allocation limits. Each fore/aft arrow pair represents two nozzles firing at the same fraction: 100% is 80 kN per nozzle, or 160 kN for the pair. The 2% display threshold corresponds to 1.6 kN per nozzle.

Attitude control and translation share the installed jets. Simultaneous demands can reduce the available response; an indication shows what the jets actually deliver, rather than the pilot's requested command. Opposing trim jets can consume fuel and show plumes while their translational forces cancel.

See RCS controls and directions and handling and shared limits for the installed force ratings and control-mode restrictions.

W-6 RCS indications

The W-6 uses the same RCS colors, signs and 2% display threshold described above, with the symbols arranged for the Manx installation. The two front circles sit beside the forward fuselage and the two aft circles sit at the wing roots, below the main-gear indications. The front lateral arrows are beside the nose; the rear lateral arrows are at the wingtips. Paired bow and aft arrows show the shared longitudinal RCS output.

For rightward translation, the left nose and left wingtip arrows light; for forward translation, both aft arrows light. A nose-up correction shows + in the front circles and − in the aft circles. These are aircraft-relative indications, including when banked, in orbit or under automatic control. Gray symbols do not mean the system is disabled: corrections at or below 2% remain hidden.

The RCS rings and arrows are separate from the green main-engine STOVL bars and their door status. Main-engine LIFT output does not light the RCS symbols. Amber RCS DATA appears above the aircraft outline when valid RCS indication data is unavailable.

W-6 spoiler indications

The W-6 has one continuous slanted spoiler-position bar on each aft wing, toward the wing root. These bars are separate from the leading-edge flaps, engine indications and RCS symbols. Engine bars and labels remain visible in front where their positions overlap.

A gray outline with a black interior means the panel is retracted. Green fill increases with extension; a fully extended panel fills the interior green. Each wing follows its own actual animated panel position, including travel between settings, rather than jumping immediately to the selected command. An amber outline means valid panel-position data is unavailable; do not interpret it as normal retraction.

Automatic ground lift dump requires ground contact, surface-relative rollout above 8 m/s (about 15.6 kt), and idle or reverse selection on all engines. It retracts at or below that rollout speed or when ground contact ends. Wind over a stopped aircraft does not count as rollout, and the parking brake is not a spoiler command. Manually selected flight spoilers remain independent. The position bars continue to indicate panel position on the ground, during VTOL/hover, atmospheric flight, ascent, suborbital coast, orbit and re-entry.

W-6 STOVL indications

On the W-6, ENG1 is the left engine and ENG2 is the right engine. Each engine has one shared 0-100% output scale for forward, reverse and downward thrust. The percentage beside the bar is their combined actual output. When more than one outlet is active, the smaller REV, LIFT and FWD numbers show its shares of that engine rating; the shares add to the total.

Forward thrust fills upward from the bottom of the bar, with animated flow toward the aft exhaust. Reverse thrust fills downward from the top, with flow toward the bow exhaust. Lift grows equally upward and downward from the engine center, with animation flowing outward left and right. Lift remains centered until an axial fill would overlap it, then moves only enough to make room. It returns toward the center as the axial fill recedes. The labels follow the same top-to-bottom order: REV, LIFT, FWD.

The engine box shows STOVL whenever actual downward output is present, including full vertical thrust and the remaining flow during spool-down after release. FWD, REV and MIX describe axial flow when downward output is zero. IDLE means powered with no outlet flow, including when the doors are open; OFF means unpowered with no flow. FAIL and DATA use the same red failure and amber unavailable-data conventions as the E-series indications.

Beneath each engine, DOOR CLSD and DOOR OPEN report the downward-nozzle door position; OPENING and CLOSING identify travel. The doors must open before downward thrust can flow and remain open through normal spool-down. DOOR --- means valid door/propulsion data is unavailable. Amber INHIB appears beneath the door status when powered propulsion is outside the permitted lift envelope or inhibited. It does not mean axial thrust is unavailable; read the engine mode and actual flow.

These indications follow the door dynamic-pressure protection during ground operation, hover, atmospheric flight, ascent, suborbital coast, orbit and re-entry. Downward thrust is inhibited above 4,000 Pa and re-enables below 3,200 Pa, subject to power, engine condition and other propulsion interlocks. There is no independent speed, altitude or vacuum restriction. In orbit, a lift request can open the doors and produce STOVL indications once downward flow begins; with no lift request or residual flow, the doors close. Forward, reverse and downward thrust continue to share one engine budget. RCS activity is separate and is not shown by these bars. Landing-gear symbols remain separate.

MFD page selection

Selecting Orbit or another MFD page does not acknowledge crew alerts or remove EICAS indications. A powered, serviceable EICAS continues showing the indications appropriate to the vehicle and its current state. Gear, engine, trim or CAS layers disappearing only while ORB1 is selected indicate a display-rendering fault; do not interpret that disappearance as a cleared alert.