Pattern 06 · Before

Intent Preview

Before the machine acts, it shows what it is about to do, so a wrong plan is caught before it becomes a wrong action. A pilot sees the proposed route as a dashed line and checks it for unexpected turns before pressing execute.

The mechanism

plan staged → act

  1. 01Plan stagedThe change is held, not applied
  2. 02 · Key momentShow the pathRoute, destination, area it will sweep
  3. 03Human checksUnexpected turns, loops or gaps
  4. 04Commit or discardExplicit execute, or erase
  5. 05ActThe machine flies the plan that was seen

At 01: Mark the proposal as provisional. Boeing puts MOD in the page title and offers ERASE, so nobody reads a proposal as the current plan.

At 03: The preview has to survive the check. At Cali the FMS dropped all intermediate fixes from its displays once a direct routing was executed.

On this page

Without / with the pattern

Without

Plan entered, then Executed unseen, then Wrong path flown

Blind Execute: the system commits a plan the human never saw. At Cali a single letter selected a beacon 132 nm away, and the turn began before anyone had checked it.

With the pattern

Plan staged, then Path shown, then Checked, then committed

The proposal is visible while it is still only a proposal, so a wrong plan is caught before it becomes a wrong action.

Sources

A preview only helps if it survives the check. At Cali the FMS dropped the intermediate fixes from its displays once the direct routing was executed, so the one picture that would have shown the turn toward terrain had already been emptied by the time anyone could look.3 The other half of the work is making the proposal unmistakably provisional: a staged change that looks identical to a live one invites the operator to read it as already true, and the pattern collapses back into Blind Execute. Where the machine moves through shared space rather than along a route page, the preview has to go where the people are — the Örebro forklift projects its path onto the floor, which is the same idea aimed at bystanders instead of at an operator.2

  1. Communicating Robot Motion Intent with Augmented RealityMichael Walker, Hooman Hedayati, Jennifer Lee and Daniel Szafir · 2018Paper
  2. That's on my Mind! Robot to Human Intention Communication through on-board Projection on Shared Floor SpaceRavi Teja Chadalavada et al. · 2015Paper
  3. Findings — American Airlines Flight 965, Cali, ColombiaIncident
  4. American Airlines Flight 965, Cali — case study2004Article
  5. Data Entry Errors Can Lead Aircraft Off CourseArticle
  6. Flight Safety Foundation, Accident Prevention (July–August 1997)1997Article
  7. The Boeing 737 CDU/FMC ExplainedArticle
  8. PMDG 737 FMC direct-toArticle