R2
Aft Service Door, aircraft right
S/B
Standby
SCHED
Schedule
SIC
Safety Information Card or Second in Command (depending on context)
SMS
Safety Management System
SOC
System Operations Control
SOP
Standard Operating Procedures
Tech Ops
Technical Operations
TSA
Transportation Security Administration
TUC
Time of Useful Consciousness
UM
Unaccompanied Minor
WX
Weather