Second‐Scale Formation of Non‐Field‐Aligned Plasma Irregularities Observed From a High‐Altitude 43‐Cassiopeiids Fireball

High‐altitude optical meteors initiating above 150 km are exceedingly rare, with confirmed observations largely confined to the Leonids. Using the Meteor and ionospheric Irregularity Observation System, we recorded a bright 43‐Cassiopeiids fireball with heterogeneous material. It initiated luminously at an exceptional altitude of 157.8 0.34 km and began ablating at ∼112.0 km. Multiple flares between 101.6 and 79.5 km were accompanied by a ∼160 s non‐field‐aligned plasma irregularity (NFAI), directly linking irregularity formation to meteoroid fragmentation. The >4 s delay between the optical event and the radar NFAI echo indicates that dust‐driven NFAIs can develop on a timescale of seconds, as ablated material vapor re‐condenses, charges, and organizes into Bragg‐scale structures. This observation provides the first direct evidence for second‐scale NFAI formation by meteors, and offers new constraints on meteor dust‐driven plasma irregularity processes in the mesosphere.