Place pre-flight checks at the prep/execution boundary…
Position pre-flight checks at the boundary between preparation and execution—after work is ready but before it begins—to catch errors when correction cost is minimal and propagation has not started.
When This Fires
- When designing verification procedures for any multi-step process
- When determining where in a workflow to place quality gates
- Before any deployment, publication, delivery, or irreversible action
- Complements When the cost of late error discovery exceeds 5x early… (phase-gate cost ratios) with the specific optimal placement criterion
Common Failure Mode
Checking too early in preparation: "Let me verify the configuration now, before I finish setting everything up." If preparation continues after the check, the verified state may change. The pre-flight check must occur after all preparation is complete — otherwise it's checking a snapshot of an evolving state, not the final state that enters execution.
The Protocol
(1) For any multi-step process, identify the prep/execution boundary: the moment when all preparation is complete and execution is about to begin. (2) Design a pre-flight checklist (Checklists are 5-10 items that catch what competent people…) positioned at this boundary. (3) The checklist verifies: is the current state what execution expects? Are all prerequisites met? Are all configurations final? (4) Execution does not begin until the pre-flight check passes. No exceptions for "we're in a hurry" — the cost asymmetry always favors the check. (5) If the check reveals an error → correct it now (preparation-level cost). If you skip the check and the error propagates → correct it later (execution-level cost, typically 5-50x higher).