How
does the glass cockpit work?
The electronics replace the
legacy environment’s use of vacuum-driven pumps and mechanical gyroscopes that
provide critical situational and directional information to the pilot through the
use of analog gauges – also known as “steam gauges” as they replicate the round
dial-type gauges that originated with steam-engine powered trains many years
ago.
All the displays/ LCDs (see
example below) used in the glass cockpit environment utilize an architecture
that applies data bus technology which implements line-replaceable units (LRUs)
that are integrated with sensors throughout the aircraft.
The sensors transmit data
seamlessly to the Primary Flight Display/Multi-function Display (PFD/MFD) units
to deliver real-time information to the pilot regarding the aircraft and its
environment. Several leading systems use the air data/attitude and heading
reference system (ADAHRS). The compact, lightweight, ADAHRS system uses a
3-axis solid state gyro and accelerometer system combined with a flux-gate
compass to replace the traditional mechanical vertical and directional gyros
thus avoiding wear and tear with age – the reliability far exceeds the legacy
system that it replaces. The separate air data computers are integrated to the
aircraft’s pitot-static system and provide altitude, vertical speed, and
outside air temperature (OAT). The system continually updates the winds aloft
and true airspeed (TAS) indications on the PFD.
Horizontal
situation indicator, airspeed and vertical speed on top, compass indicator with
location overlay on the bottom. One clear picture in an easy-to-interpret
display.
How weather information is provided to the PFD:
The illustration above
shows how the data is collected and distributed for use in the PFD display shown
here which the pilot utilizes for weather monitoring purposes in flight. Notice
the aircraft’s route of flight just to the right of a storm.
Maintenance is fairly
straightforward and can be done by most aviation technicians and avionics
specialists. Such specialists are typically certified on the equipment they service
and understand the integration complexities specific to their type of
equipment.
Not all manufacturers have
the same display characteristics in terms of dimensions and overall
layout. Users will typically select out
of several that are available through the aircraft manufacturer that are
certified for the aircraft type. All
equipment installed in an aircraft is required by FAA law to receive
certification.
The certification process is
a critical step as it is rigorous from a standards perspective and incorporates
key safety requirements such as mean time between failure rates, and secondary
backup capabilities and emergency process/procedures. A typical certification process can take up
to three years to complete depending on the level of complexity of the aircraft
and equipment.
Definition: What is a “glass”
cockpit?
A modern commercial example – The
Boeing 747 – “Then and Now”
History and Background –
Technology Profile
How does it work? – A brief
explanation of the glass cockpit components
The Transformation from commercial use to General Aviation – Recent Applications