More complicated are drifts in the fractional reserve level and trends in international outflow requests, which put sustained pressure on the window and cannot be tackled at the source.

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If the regulating valves fail or if the cabin structure is breached (by a failure of a door or window for example) then the pressure in the cabin would suddenly drop to match the outside air pressure.

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There was a huge wave of selling pressure in the markets in the hour before that window.

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