Cross-Check Before.
Monitor During.
Review After.

This behaviour is sometimes read as a more continuous version of task verification — a repeated checking of outcomes rather than a single closed loop at the end of each action. That is not quite right. Reviews, monitors and cross-checks actions constantly operates across a different timescale and with a different purpose. Where verification asks did the action produce the expected outcome, this behaviour asks something earlier and more continuous: is what I am about to do the right action, is what I am doing proceeding as intended, and is what I did actually what I meant to do?

The three elements are sequential, not simultaneous. They operate before, during and after — and the most important of them, operationally, is the first.

Cross-Check Before

The cross-check is the pause — however brief — between intent and action. The moment of confirmation that the control being reached for is the correct one, that the action being about to be taken is the right one for the current situation, that the instruction being about to be executed matches what was received and understood.

It intercepts errors before they become consequences. And the errors it intercepts are not errors of ignorance. A crew member who selects the flap lever instead of the speedbrake, or moves a control before the correct phase, or acts on an outdated clearance — is not demonstrating a lack of knowledge. They know perfectly well what each control does. The error is an attention error: action outrunning awareness, habit patterns misfiring under conditions that slightly changed the expected sequence. From outside the cockpit — or inside it at low workload — these lapses appear inconceivable. Under pressure, with divided attention and a high-demand operation, they happen to experienced, competent crews.

The cross-check is the mechanism that closes the gap between what the crew member intends to do and what they are actually about to do. It requires a moment of directed attention before the action. That moment is the discipline. And like all such moments, it is easy to skip under pressure — which is exactly when it is most needed.

Monitor During

Monitoring is the ongoing observation of an action in progress — the continuous comparison of what is happening against what should be happening. It is active, not passive. It requires attention directed at the right outputs, a clear expectation of what those outputs should show, and the processing capacity to register when they diverge.

There is a pace dimension to monitoring that is often overlooked. An action executed at a pace that outstrips the monitoring ability of the crew member performing it — or the crew member observing it — has removed the safety net at the moment of highest risk. The PM exists to monitor. If the PF moves faster than the PM can track, the crew is effectively operating single-crew at precisely the moment when two pairs of eyes have the most to contribute. The pace of action is itself a workload management and situational awareness decision. Slow enough to be monitored is not a constraint on performance. It is a component of it.

The small change before the large one is the practised expression of this principle. A small heading adjustment, observed and confirmed, before the full turn. A partial control input, checked for response, before the committed one. The small change is not indecision — it is verification built into the action itself, reducing the consequence of the unexpected before it can become significant.

Review After

The review is the closing element — the confirmation that the action produced the expected result and that the situation is as it should be following the action. This is where it connects to task verification, but it is not the same thing. Verification is the specific closed loop for a defined task. The review is broader: a periodic assessment of whether the cumulative picture — across multiple actions, across the developing flight — is consistent with what was planned and expected.

The review catches the things that individual task verifications miss — the slow drift that no single action caused, the accumulated divergence between the expected state and the actual one, the assumption that was made early in the flight and was never checked against evolving reality. It is the behaviour that keeps the picture current not just at the action level but at the flight level.

The Habits That Will Be Assessed

The simulator checks the standard. The line operation is where the standard is built. And the gap between structured training events — the months of routine flying that fill the space between LPC and OPC — is where the habits that will appear in the assessment are actually formed.

This is the closing argument for this behaviour. Cross-checking, monitoring and reviewing consistently in normal operations is not about performing for an observer. It is about building the habits that run automatically when the operation is demanding enough that deliberate application is no longer possible. Under pressure, the crew member does not choose to cross-check — they do it because they always do it. Or they do not, because they never consistently did.

If the habits built across the majority of line flying are inconsistent — sometimes disciplined, sometimes not, depending on workload or fatigue or complacency — they will not reliably appear in the assessment environment. And more critically, they will not reliably appear in the situations where their absence has the most consequence. The simulator assesses what the habits produce. The line is where the habits are formed. What happens in the gap between events is not a break from development. It is where development actually occurs.