Corrected entry: The Dallas submarine chasing Red October uses a very sophisticated sound analysis to localize the Russian sub because of its silent drive system. Red October does not notice the Dallas with its conventional propeller drive at all, until it deliberately reverses the propeller at full throttle at close distance. The Red October is not (deliberately) deaf however: the aircraft dropping a torpedo is signaled from great distance, but not the Dallas surfacing and picking up Jack Ryan from a helicopter. Furthermore, "crazy Ivan" turns are made to be sure no sub is following them, yet the encounter with the Dallas comes as a surprise.
Carl Fink
21st May 2005
Correction: The American sub has much better sonar, and the Dallas is in fact extremely quiet, even if it doesn't have the caterpillar drive. Torpedoes splashing into the water from a plane would be easy to detect.
Carl Fink