I found this interesting enough to look into it a little more:
> At 30,000 ft. a sharp crack rang through the ship, shaking it violently. The water pressure outside wasmore than 6 tons per sqare inch., and even a slight fracture in the hull would have meant certain death. It proved to be only an outer Plexiglas windowpane which had splintered under the pressure. The inner hull remained watertight. "A pretty hairy, experience," admitted Walsh.
> At 30,000 ft. a sharp crack rang through the ship, shaking it violently. The water pressure outside wasmore than 6 tons per sqare inch., and even a slight fracture in the hull would have meant certain death. It proved to be only an outer Plexiglas windowpane which had splintered under the pressure. The inner hull remained watertight. "A pretty hairy, experience," admitted Walsh.
https://web.archive.org/web/20070202144233/http://bjsonline....