Which method of navigation relies solely on computations without visual reference?

Dead reckoning is a navigation method that relies on calculations based on the aircraft's previous position, speed, heading, and time. It allows pilots to continually update their position through mathematical computations without needing visual references from the environment. This method uses the last known position and applies headings and speeds to estimate the current location. Conditions such as poor visibility or reliance on instruments make dead reckoning particularly essential, as pilots may not have the ability to see landmarks or navigation aids.

In contrast, pilotage relies on visual references to navigate based on identifiable landmarks and features on the ground. Visual tracking also correlates closely with the observation of the environment and is not solely a computational method. Instrument guidance involves using aircraft instruments to navigate, which can rely on external signals and often requires visual confirmation, negating the aspect of solo computations inherent in dead reckoning. Thus, dead reckoning stands out as the correct answer due to its exclusive reliance on computations and not on visual cues.