787 Flight Crew Operations Manual
DO NOT USE FOR FLIGHT
Flight Instruments, Displays -
Head-Up Display System
Description
Copyright © The Boeing Company. See title page for details.
D615Z003-TBC 10.22.3
Pitch Scale Compression and Chevrons
The HUD pitch scale normally displays 5º lined increments above and below the
horizon reference line, and conform with the outside world. For example, as the
pilot looks through the HUD, the horizon reference line on the HUD pitch scale
should rest at or near the actual horizon outside the airplane. At higher altitudes,
the HUD horizon reference line may appear slightly above the actual horizon due
to curvature of the earth.
If the HUD horizon reference line or the flight path vector symbol cannot be
shown on the display when it conforms with the outside world (excessive pitch up
or pitch down), the pitch scale compresses to make room for these symbols. The
pitch scale then displays 10º increments.
At excessively high or low pitch angles, chevrons are displayed directing the pilot
to pitch the airplane back toward the horizon. For example, if the airplane pitch
angle is excessively high, a downward pointing chevron positioned on the +30º
pitch scale line comes into view, directing a pitch-down command to the pilot. If
the airplane pitch angle is excessively low, an upward pointing chevron positioned
on the -20º pitch scale line comes into view, directing a pitch-up command to the
pilot.
Unusual Attitude (UA)
The UA symbology displays when airplane pitch angle exceeds -20º or +35º, or if
roll exceeds 55º in either direction. Only symbology necessary to help recover
from the situation is displayed. The UA symbology replaces the full or decluttered
symbology. Any pitch scale compression with chevron is also replaced by the UA
symbology.
The UA symbology remains displayed until the airplane pitch angle is between -5º
and +10º (relative to horizon) for 5 seconds, and roll angle is less than 10º for 5
seconds. Once the recovery maneuver is within these limits, the UA symbology is
replaced by the full-symbology mode, regardless of the mode the HUD was in
before encountering the unusual attitude.
The UA symbology includes a zenith symbol centered on the +90º pitch scale line,
and a nadir symbol centered on the -90º pitch scale line.
Digital Heading
A numerical digital heading value displays current heading below the roll scale
slip/skid indicator. This value corresponds to the heading on the horizon reference
line of the pitch scale.
February 15, 2010
To Next Page
Loading...
