Minor point: the other planes have <i>weather</i> radar, but that isn&#x27;t useful for traffic detection. Only military aircraft have radar systems designed to pick up other traffic.<p>Some airliners have active traffic systems (most do not), but the real reason it&#x27;s safe is that all the airliner and jet traffic is cruising well above where the piston-engine aircraft are flying. (The pistons will also be on high-frequency radios, making periodic position calls to Oceanic control, but those are more for the safety of that aircraft and less for traffic de-conflicting.)