It sounds like an engine, idling.
For seventeen seconds, the An-990 sang a note that did not exist in nature. It was the frequency of a womb. The frequency of a door closing. The frequency of the instant before a lightning strike.
The “I” stood for Izbishche , an old Ukrainian word for a slaughterhouse. But the engineers simply called it “The Ghost.” i--- Antonov An 990
The I-Carrier
The sensors went white. The 990 did not crash. It did not explode. According to the telemetry, the aircraft simply ceased to be in the air. One moment it was a sixty-ton mountain of Duralumin and titanium. The next, it was a perfect, three-dimensional shadow of itself, painted onto the clouds below. It sounds like an engine, idling
On that night, the I--- Antonov An-990 rose from a hidden airstrip near the Aral Sea. It reached operational altitude at 02:00 local time. The ground crew, wearing double-layered ear defenders, watched the altimeter tick past 15,000 meters. The order came over the scrambled channel: “Carrier, this is Hearth. Execute Lullaby.”
Then, the resonance loop collapsed.
Kyiv International Exposition of Unorthodox Aeronautics, 1989 (Alternate Timeline)