What is EFIS / Glass Cockpit?

EFIS (Electronic Flight Instrument System) is an integrated cockpit display system that replaces classical round mechanical instruments ("steam gauges") with digital, computer-driven displays. "Glass cockpit" is the colloquial term for a cockpit with predominantly EFIS displays.

Advantages over mechanical instruments:

Clearer presentation,
Integration of multiple data on one screen,
Programmable/configurable (layout, units, symbology),
Lower weight and fewer moving parts,
Better diagnostics and self-tests.

Disadvantages:

Full dependence on the electrical system and computer,
Requires pilot training (Differences Training under FCL.710),
On failure: fallback to standby instruments is mandatory.

Main EFIS components

Primary Flight Display (PFD)

The PFD replaces the classical "Six Pack" flight instruments (airspeed, attitude, altitude, turn, heading, VSI). Typical elements:

Attitude indicator as the central element, often filling the entire screen width.
Airspeed tape (vertical speed band) on the left: current speed as digits, V-speeds (Vs0, Vs, Vfe, Vno, Vne) as coloured markings, trend vector.
Altitude tape on the right: current altitude as digits, selected altitude (FMS/bug), QNH display.
Vertical Speed Indicator (VSI) beside altitude tape, as scale or digit.
Heading indicator (HSI) below: compass-style, with selected heading bug, CDI deviation (VOR/GPS), DME, ETA.
Slip/skid indicator as a trapezoid below the attitude display.
Trend/bug indicators: selected altitude, heading, airspeed, V-speeds.

Multi-Function Display (MFD)

The MFD shows non-primary information:

Moving map with chart, flight path, waypoints, airspace,
Engine indications (engine monitoring): MAP, RPM, EGT, CHT, oil pressure/temperature, fuel,
Flight plan and navigation,
TAWS / terrain awareness with terrain warnings,
Weather radar / stormscope / datalink weather,
Traffic information (TIS, ADS-B IN),
Checklists, approach charts.

Common GA glass-cockpit platforms

Garmin G1000 / G1000 NXi — widespread (C172, C182, DA40, DA42, …).
Garmin G3X Touch — Experimental and now certified.
Dynon SkyView / HDX — Experimental and certified types (STC).
Avidyne Entegra.
Aspen Evolution — retrofit PFD for standard 3" instrument hole.

Display technologies

LCD (Liquid Crystal Display) — current standard:

Backlit, high resolution, low power consumption.
TFT active-matrix LCDs with wide viewing angle.

OLED and AMOLED — rare on certified aircraft due to lifetime and temperature requirements.

Limitations:

Direct-sun reflections — sun-shade, polarising filters, high brightness (1 000+ cd/m²).
Temperature range — typically −20 °C to +55 °C; cold start may delay boot.
Boot-up time — a few seconds to one minute.

Symbology

EFIS symbology follows ARINC 661 and DO-178C as software certification standards. Typical symbols:

Attitude: blue sky above, brown ground below, white horizon with pitch scales, bank pointer at top with markings at 10°, 20°, 30°, 45°, 60°.
Speed tape: white = Vs0–Vs1, green = Vs–Vno, yellow = Vno–Vne, red line = Vne.
Altitude tape: large digits for thousands, smaller for hundreds; selected altitude as bug.
HSI: red lubber line forward, rotating compass card, CDI display.

Failover / standby instruments

EASA and FAA require for IFR-certified glass-cockpit aircraft:

Standby attitude indicator (mechanical or self-battery),
Standby airspeed indicator,
Standby altimeter,
Standby compass (magnetic "whiskey" compass).

On PFD failure the pilot switches to standby instruments — should be trained routinely.

Reversionary mode

On failure of one display the other can take over — the so-called reversionary mode: PFD and MFD functions are consolidated on a single screen (smaller fonts, congested). In G1000: red "RVRT" knob or automatic on fault detection.

Pilot requirements

Differences Training under Regulation (EU) 1178/2011 FCL.710 is required when a pilot moves from analogue instruments to glass cockpit. Content:

Operation of knob/touchscreen concepts,
Symbology and layout,
Reversionary mode and standby procedures,
GPS navigation, flight plan, direct-to.