When is "Static Boost" noted?

Static Boost refers to the pressure boost observed in an engine system before the engine is started. This measurement is crucial for understanding the baseline performance and readiness of the engine at rest, without the influence of engine operation or airflow that occurs during runtime.

When examining the circumstances surrounding "Static Boost," it is vital to consider that this measurement is taken with the engine off, allowing for a clear, unaltered reading of the boost pressure that can be expected from the engine when it is operational. This provides valuable information for mechanics and pilots regarding the engine’s condition and the boost system's integrity without any external influences.

In contrast, other options imply conditions during or after engine operation which would not accurately represent "Static Boost." For instance, measuring boost just after engine start would involve dynamic conditions where the engine is beginning to operate, thus not qualifying as a static measure. Similarly, being permanently marked on the boost gauge or calculated from airfield QNH involves factors that do not coincide with the concept of static measurements, as they refer to ongoing readings or additional calculations rather than an initial static state prior to operation.