The common feature, the borrowed expression, and the contextual indicator have different roles. In *ṭāra ilayhā*, the verb for flying supplies the imagery; rapid movement toward an alarm is intended; the human setting precludes taking bodily flight as the literal claim.
The common feature explains what grounds the analogy. The indication shows why the literal sense is not intended. The speaker's communicative goal ties these elements together.
Merely identifying “speed” is therefore an incomplete analysis. One must also identify the two meanings being connected and the evidence for the figurative use.