Originally Posted by
BizJetJock
Actually, and counterintuitively, exactly the opposite is true. The below is from the Challenger 605 FCOM. Note 1 is interesting.
That’s odd. I was so intrigued by what you quoted, I found this reference:
http://www.smartcockpit.com/docs/CL6...ON_SYSTEMS.pdf
”In-Flight Alignment
If a power interruption or a transient system fault occurs in-flight, and a GPS signal is valid, the IRS system will have the capability for re-alignment. During in-flight re-alignment, the IRS ALIGNING message appears on the PFDs.
The FMS will prompt the crew with the SET IRS HDG amber message on the FMS CDU scratchpad (required for FMS navigation – IRS will align without this action). If the crew enters a heading, the IRS will work as a DG until it transitions to the ATT mode, at which point it starts calculating its own HDG.
Typically, the time required for a full alignment in navigation mode is between 10 to 20 minutes. At the beginning of the alignment process
, it is recommended that the aircraft maintain a straight and level flight attitude (see Note 1).
NOTE
1. Aircraft maneuvers involving changes in heading increase the alignment time.
2. The alignment time increases as a function of latitude, with the minimum time occurring at the equator, and the maximum time occurring at the poles.