Life-Support Alarm Console: Interface Design & Operator Response

Console Interface Design

Panel layout

Color-coded alerts

Alarm rate 18 / min

Panel size (target width W) 1.00×

Operator Performance

Active alarms

Total triggered

Avg response (measured)

— ms

Avg response (predicted)

— ms

Missed alarms

False clicks

Cognitive load

0 / 100

Movement dist. D

— u

How it works

Six simulated ECLSS subsystems (O₂, CO₂, cabin pressure, temperature, power, water) each drive six indicator panels on a 6×6 console. Alarms fire at random (biased 60% toward the same subsystem as the previous one, since real cascading faults cluster) and must be acknowledged by clicking the lit panel before a 9 s timeout.

Predicted acknowledgment time combines three well-established human-factors models:

Fitts's Law (pointing):   MT = 0.15 + 0.20·log2(D/W + 1)  s
Hick-Hyman Law (choice):  DT = 0.20 + 0.15·log2(N + 1)    s
Serial search (mono only): ST = 0.05·(36/2)               s
Predicted RT = DT + ST + MT

D is the real 3D distance from the previously acknowledged panel to the new alarm, W is the panel's rendered width (the size slider), and N is how many alarms are simultaneously active (more choices = slower decisions, per Hick-Hyman).

Color-coded alerts — active panels glow at full brightness in their subsystem's hue: a pre-attentive "pop-out" that visual-search theory (Treisman & Gelade) predicts is found in roughly constant time regardless of how many panels exist.
Monochrome — active panels only get slightly brighter with no hue difference, forcing a serial scan of the console; the model adds ~0.05 s per panel scanned (half of 36, on average).
Grouped layout — same-subsystem panels sit in one row, so a cascading fault keeps D small. Scattered randomizes the subsystem-to-cell mapping, inflating D for the same cascade.

The "Cognitive load" readout is a heuristic 0–100 composite of alarm density, miss rate and whether color coding is off — illustrating why real spacecraft HMI standards (e.g. NASA-STD-3001) mandate color- and priority-coded alerting.

O₂ CO₂ Pressure Temp Power Water

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