terrain-hugging air-breathing low-flying vehicles

nap-of-the-earth (NOE) (ground-hugging / terrain masking / flying under the radar / hedgehopping)

low flying aircraft / low-flying aircraft

terrain hugging

low-flying, low-speed drone

all-terrain vehicles (ATVs)

accident-free flying / mishap-free flying

mishap-free flying / accident-free flying

terrain flying

air-breathing jet engine

fresh-air hose breathing apparatus

air breathing engine

compressorless air-breathing jet engine

ram air-breathing jet engine

air breathing defense

air breathing missile

air breathing target

anti-low-flying aircraft missile

authorized low flying

low flying

low flying operation

low-flying targets

long-endurance unmanned air vehicles

low-RCS target / low-radar-cross-section target

breathing control

scuba (Self-Contained Underwater Breathing Apparatus)

self-contained breathing apparatus (SCBA)

engine breathing ability

hose breathing apparatus

hose breathing device

CABCDE (Critical Bleeding, Airway, Breathing, Circulation, Disability, Exposure)

breathing system

oxygen-breathing apparatus