Some thoughts
There will be others more knowledgeable than me, but as a starting point
Define:
Critical Missions:
SAR usually means people's lives are at risk (30 minute from call-out to ready to take-off)
Complex Jet:
Complex operating environment? Not just the aircraft but includes the 19 day course at Bombardier to sit in FO seat + low level + SAR equipment / search training + crew integration
Low level:
possibly "below 500FT" (AMSA web site - Recommended Search Heights")
Slow speed drops: ?? (around 150kts?)
Inclement wx:
not always this bad, but thinking back to the 1999 Sydney to Hobart. Helicopters and P3s operating in cyclonic conditions
Not fully automated flight deck:
At low level, I don't imagine there would be much time on auto pilot with relatively frequent changes in search legs
regards
layman