Quiescent Flight

Quiescent Flight refers to periods of calm or when ship motions are within acceptable limits, allowing for safe operations like helicopter landings or UAV operations.

Here's a more detailed explanation:

Purpose:

Predicting and identifying quiescent periods is crucial for various shipboard activities, especially those involving airborne vehicles (helicopters, UAVs) or landing crafts.

Quiescence Definition:

Quiescence refers to the time interval during which ship motions (roll, pitch, heave, etc.) are within acceptable limits for a specific operation.

Importance:

• Helicopter Landings: Helicopter pilots and Landing Safety Officers (LSOs) need to know when ship motions are stable enough for a safe landing.
• UAV Operations: Similar to helicopters, UAVs also require a stable platform for take-off and landing.
• Other Operations: Quiescent periods are also important for other shipboard operations that are sensitive to motion, such as launching or recovering landing crafts.

Flight Deck Motion System (FDMS):

Systems like the FDMS are designed to assist LSOs in identifying when ship motions are within limits, providing a "Quiescent Period Indicator" (QPI).

Predicting Quiescent Periods

There have been efforts to predict ship motion in real time. The first approaches were based on analyzing recent ship motion records. More recently, new measurement methods have been introduced that measure wave height from distance. This has increased the prediction horizon.