What was the major risk shown with controlled rest?

• A. Improved situational awareness
• B. Loss of monitoring → both pilots not fully aware
• C. Reduced workload
• D. Increased reliability

Answer: (B)

Controlled rest is a fatigue countermeasure used on long flights where one pilot takes a brief nap while the other remains at the controls to monitor the flight. The major risk here is loss of monitoring. While one pilot sleeps, the awake pilot must handle flight management, navigation, communications, and monitoring of the automation and external environment. If attention lapses or if the situation rapidly changes, crucial cues can be missed or misinterpreted, and during the transition in and out of the rest period there can be a temporary gap in full situational awareness. This is why the emphasis is on maintaining vigilance during the rest window and ensuring strict procedures for wake-up, handover, and monitoring. The other options don’t capture this risk: resting reduces the rested pilot’s workload temporarily but doesn’t inherently increase monitoring risk; improved situational awareness isn’t the outcome during the nap itself; and increased reliability isn’t the immediate risk of the rest practice.