sonic

Overview

A "sonic" is a sledge‑mounted sensor and display used by drivers to detect hidden crevasses in ice. It presents a continuously scrolling trace on a small screen and is treated as essential equipment when operating over glaciered terrain near the northern coastal passes.

Description and Use

• Operation: The device emits sound waves and interprets reflections from the ice ahead to reveal voids and weaknesses. Its output appears as a jagged line that scrolls horizontally as the vehicle moves.
• In‑cab placement: Observed mounted above a crawler’s control panel where the driver and passengers can see it at a glance.
• Practical guidance: A traveling companion’s rule of thumb was to never entrust oneself to a sledge that lacks a working sonic. In practice, travelers compared options and chose a sledge where the driver visibly had one active.
• Role in rough country: Sonics are used to avoid crevasses that might swallow a tractor and its sledges; even long treads cannot bridge every hidden gap.

Provenance/Ownership

• Typical users: Sledge drivers—including small, short‑range smugglers who shadow main lines near the port region—fit sonics to their crawlers for safety.
• Context of use: During an over‑ice approach to a northern harbor, a driver’s cab displayed a functioning sonic while courting passengers. In the same period, a large military convoy of the Sæcular Power was observed moving through the area.

Notable Mentions

• While trying to bypass a sledge port in foul weather, an avout traveler noted a glowing screen showing a jagged trace—identified as a sonic—and chose that vehicle accordingly. Conditions on that route also included jamming of navigation satellites attributed by speakers to the Cousins and heavy convoy traffic by the Sæcular Power.
• In subsequent hazards on the ice, the traveler relied on the avout kit (notably the sphere) for rescue after a crevasse accident; the sonic’s role is preventative rather than remedial and is cited as a key reason to select a properly equipped sledge.

Related

• Community/role context: The observer is an Avout traveling extramuros with limited gear and guidance, which frames the cautionary emphasis placed on having a sonic when selecting transport.