Clacker
No
Yes, slow down
ADIRU (Air Data Inertial Reference Unit)
Failure of both GPS sensor units
Failure of a single GPS unit
IRS operating in ALIGN, INITIAL, ATT or SHUTDOWN cycle
Difference in position entered or no position entered
 No
the system is in NAV and aligned?
No, could be in ATTITUDE
on the IRU panel?
ATT or NAV fault is detected in IRS
Momentary self test when first turned on or AC power not normal
DC power not normal
No, integrated standby flight instruments (ISFD) or standby instruments and STBY compass
IRS Display Unit (ISDU)
alignment?
Yes
5 to 17 minutes (7 to 10 a tour latitudes)
remaining in the alignment process?
ISDU-HDG / Status Pos
Self Test
Backup?
Standby AC; Switched hot battery bus
Backup?
AC Transfer bus #2, Switched hot battery
Verify Position
short turnarounds?
Align, EnterPosition, NAV or Align, NAV, Enter Position
30 Seconds (aircraft must remain stationary)