Few aircraft have returned to service under a heavier cloud of suspicion than the Zephyr 400, the battery-electric floatplane that Coastwing Airways continues to fly along the coast despite an unresolved safety record. Federal regulators had grounded the aircraft in 2023 following a string of serious battery failures whose underlying cause has never been fully established, and yet, within a matter of months, the same authorities cleared it once more to carry paying passengers. That reversal is precisely what troubles the Zephyr's critics, and it is worth tracing how it came about.

Determined to reach the market ahead of a European rival, the plane's builder, Skyforge Aviation, hurriedly bolted extra cooling onto the suspect battery units and put them through a cursory, only half-scientific round of testing. Those results were nonetheless enough to persuade Transport Canada that the battery no longer posed a hazard, and the regulator cleared the aircraft to fly again well before the Transportation Safety Board had finished its own investigation. The Board registered its displeasure in an unusually blunt letter, one that called for far greater reliance on genuinely independent experts and for tighter, more standardized checking of the components from which such aircraft are built.