Zitiere 737:
Alignment (On the Ground)
An IRS must be aligned and initialized with the aircraft position before it can
enter the NAV mode. The position is normally entered through the FMC CDU
during alignment. If the position cannot be entered through the FMC CDU, it
may be entered through the ISDU keyboard. The aircraft must remain
stationary during alignment. Alignment time varies from five minutes to
seventeen minutes depending on aircraft latitude.
Normal alignment, between 70º12’ north and 70º12’ south latitudes, is initiated
by rotating the IRS Mode Selector from OFF directly to the NAV position. The
IRS performs a short DC power test, during which the ON DC light illuminates.
When the ON DC light extinguishes and the ALIGN light illuminates, the IRS has
begun the alignment process. Aircraft present position should be entered at this
time. The IRS will automatically enter the NAV mode after approximately 10
minutes, and the ALIGN light will extinguish.
Zitiere 747:
IRS Alignment
Full Alignment
Rotating the IRS mode selector from OFF to NAV begins IRS alignment.
Alignment requires approximately ten minutes. Present position (latitude and
longitude) must be entered on the CDU position initialization page to complete
alignment. Alignment can be accomplished only when the airplane is parked.
Alignment stops if an IRU detects motion during alignment. Alignment continues
and completes in approximately ten minutes after motion stops. The IRS is aligned
when all IRUs enter the navigation mode. Latitude and longitude entries then
blank on the SET IRS POS line on the CDU position initialization page.
Alignment is lost if the selector is moved out of theNAV position.
A full alignment, accomplished by rotating the IRS mode selector to OFF and
back to NAV, must be accomplished when the time from the last full alignment to
the next expected arrival time exceeds 18 hours.
Was noch interessant ist:
The FMC uses GPS position data to estimate errors in the inertial reference system
(IRS) position and velocity.
Achso mal eine Farbliche Beschreibung eines RNAV APP:
http://www.smartcockpit.com/site/pdf/do ... proach.pdf
Quelle: http://www.smartcockpit.com
Hab die Lösung. In den Alten Fliegern ist das IRS anders aufgebaut...
Inertial Reference System is the actual inertial platform that measures the acceleration inputs in all axes that provides the means of measurement and computation to the INS. This can be gyro (either free or strapdown) or ring laser. This measurement is relative to a starting point in space, therefore the INS must be oriented and aligned with the grid along which it must provide navigational information. In our case reference earth and Lat and Long. This is why it is necessary for the sytem/aircraft to remain stationary for a period of time on system start up to set reference zero acceleration within the IRS and allow alignment with the navigation grid and reference time. The old gyro systems may have taken up to 60 minutes to align with the modern ring laser only minutes.
