countdown

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countdown

[′kau̇nt‚dau̇n]
(aerospace engineering)
The process in the engineering definition, used in leading up to the launch of a large or complicated rocket vehicle, or in leading up to a captive test, a readiness firing, a mock firing, or other firing test.
The act of counting inversely during this process.
(communications)
The ratio of the number of interrogation pulses not answered by a transponder to the total number received.
(engineering)
A step-by-step process that culminates in a climatic event, each step being performed in accordance with a schedule marked by a count in inverse numerical order.
References in periodicals archive ?
A mission dress rehearsal, including a simulated count-down exercise, is held a few weeks prior to launch.