rough engine operation

rough terrain container handler (RTCH)

rough ditching

rough abrasive cloth

Rough Order of Magnitude

rough landing

rough bar

engine capacity / engine power, engine output

clandestine operation; covert operation

humanitarian operation; humanitarian relief operation (HUMRO)

PZ operation (pick-up zone operation)

noncombatant evacuation operation (NEO); non-combat evacuation operation

underwater operation of engine

cut-off engine operation

engine run-up operation

idling engine operation

reaction engine / motor (jet engine)

rotary engine (Wankel engine)

engine ground run / engine test

engine oil reservoir / engine oil tank

aeromobile operation

African Union / United Nations Hybrid operation in Darfur (UNAMID)

air defense operation

air logistic support operation

air operation

airborne and amphibious operation

airborne assault operation

airborne/ amphibious operation

air-land operation

air-landed operation

airmobile operation

alien migration interdiction operation

Alliance operation