Under what condition would you typically use an instrument takeoff?

An instrument takeoff is typically not a common procedure and is generally only performed under specific conditions, such as low visibility due to weather or other restrictions. The primary reason for this is that the majority of airports and takeoff procedures are designed to utilize visual references, and using instruments for takeoff is largely unnecessary in clear weather conditions.

While it's true that there could be exceptional reasons for conducting an instrument takeoff—like when no clear visual references are available, selection of departure paths, or safety protocols in busy airspace—the norm is that most operations can commence visually. This places the use of an instrument takeoff in a more rare category, hence the prevalent understanding that it occurs almost never unless under strict procedural requirements, such as low weather minima or specific operational directives.

In comparison, the other options imply scenarios where instrument takeoffs might be more common, but that is not typically the case. For instance, high-density traffic areas usually have strict adherence to visual operations in clear weather, and instrument operations are mainly a function of safety and altitude in adverse conditions rather than time of day. So, the correct answer reflects the reality that instrument takeoffs are indeed rarely used, affirming option C as the most accurate choice.