When does the strip become deadwood if the emergency lands at KJAN?

The correct answer is identified when considering the concept of "deadwood" in the context of radar operations. A strip becomes deadwood when it is no longer needed for active traffic control, meaning that the flight in question has safely completed its operations.

In this scenario, the strip becomes deadwood upon the frequency change. This is because a frequency change typically signifies that the aircraft is transitioning to a new phase in communications, often relating to being on the ground or handed off to a different facility or service. Once the aircraft successfully switches frequencies and is presumably landing or on the ground, the need for the pre-landing strip diminishes, as its operational role has concluded.

The other factors, such as receipt of a landing time or confirmation from the pilot, are important but do not mark the definitive point at which the strip is considered deadwood. The supervisor's notification may also be essential for tracking or administrative purposes but does not indicate the actual operational need for the strip. Thus, the correct identification of when the strip becomes deadwood is tied to the moment of the frequency change, solidifying the transition from active to inactive status.