Intent Preview

Before the machine acts it displays a proposed plan so a wrong plan is caught before it becomes a wrong action.

American Airlines Flight 965 at Cali

20 December 1995 · Buga, Colombia

Flight 965 was descending toward Cali at night when the crew accepted a late change of approach. Rushing, the captain typed “R” into the flight computer to select the Rozo beacon. The computer took it as Romeo, a beacon near Bogotá some 132 miles to the north-east, and the autopilot began turning toward it. Nobody saw the new path until the aircraft was off course over mountains; it struck one, and 160 of the 164 people on board died.3

Anti-pattern: Blind Execute

The system commits a plan the human never saw. The entry is accepted, the turn begins, and the first evidence of the mistake is the machine already making it.

Intent Preview

Therefore: Show the path before it is flown, and make committing to it a separate act from proposing it.

Without

Flight computer

ACTIVE ROUTE

ROZO 8 MI

CALI APPROACH

Type R and press Enter.

With the pattern

Flight computer

ACTIVE ROUTE

ROZO 8 MI

CALI APPROACH

Type R and press Enter.

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

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
On this page

Sources

A preview only helps if it survives the check. On American Airlines Flight 965 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