FAA radar personnel

Directness and Evidential Scope

Controllers directly observed their displays and heard the crew.

Their evidence is strongest for:

• the reality of the operational report;
• timing;
• air-traffic context;
• known aircraft;
• whether a return appeared on a specific scope;
• whether another crew confirmed a visual target.

They cannot identify the physical source solely from a brief radar return.

Radar Systems and Display Interpretation

The case involved different radar systems and possible primary and secondary returns.

Relevant distinctions include:

• secondary radar: replies from aircraft transponders;
• primary radar: reflected radio energy from targets or environmental sources;
• military radar: potentially different processing and coverage;
• display artefacts: split targets, propagation, clutter or correlated returns.

A controller's statement that a return appeared near JAL 1628 does not by itself show a separate physical object. It may represent:

• the aircraft itself;
• a split or duplicate return;
• weather;
• another aircraft;
• processing artefact;
• an unidentified target.

Correlation with the Crew Report

Radar corroboration is strongest when the return:

• appears at the reported bearing and range;
• moves consistently with the visual target;
• remains distinct from the aircraft;
• appears across more than one sensor;
• is recorded in raw data;
• can be reconstructed independently.

The public record contains intermittent and disputed returns rather than a continuous track matching the visual narrative.

FAA's Inability to Confirm

The FAA's conclusion that it could not confirm the event should be interpreted carefully.

It means the available agency evidence did not verify a separate extraordinary object. It does not prove that the crew saw nothing.

The distinction is:

• confirmed operational report: yes;
• confirmed radar target matching the reported object: no;
• identified visual stimulus: no.

Nearby United and Military Aircraft

Controllers asked other aircraft to look for the reported object.

The failure of nearby crews to see it is relevant because it limits:

• duration;
• angular size;
• persistence;
• the claim of a vast object visible over a wide area.

It is not decisive because viewing angles, cloud, distance and timing differed.

Captain Terauchi's Onboard Radar

Terauchi reported that the aircraft's weather radar showed a target.

Weather radar is designed to detect precipitation, not to provide a reliable air-to-air target track. Returns can arise from:

• weather;
• ground clutter;
• anomalous propagation;
• system settings;
• reflections.

The crew's interpretation is relevant but not equivalent to an air-traffic-control radar confirmation.

Controller Independence

Different controllers and military personnel may provide independent sensor perspectives.

Their independence is reduced where later accounts relied on:

• the same recorded scope data;
• shared telephone coordination;
• the crew's descriptions;
• post-event briefings;
• one analyst's interpretation.

The record should identify the precise system and operator for each claimed radar contact.

Shape and Scale Claims

The most dramatic visual claim involved a large dark object behind or near the aircraft.

Radar personnel did not directly verify its shape or carrier-scale dimensions.

A radar return cannot ordinarily establish a visual outline without specialised imaging. Scale estimates remain part of the cockpit testimony.