From marshal, helicopters descend at how many knots and how many feet per minute, crossing 145 degrees relative to the final bearing at or above how many feet?

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Stabilized arrival patterns for helicopters use set airspeed, descent rate, and crossing altitude to guarantee safe alignment with the final approach. The correct combination is 90 knots, 500 feet per minute, and crossing at or above 900 feet. A speed of 90 knots provides enough forward motion for controllability and a stable profile during the approach; a descent rate of 500 fpm keeps the helicopter descending smoothly without overloading lift or creating excessive rotor wash; crossing 145 degrees relative to the final bearing means approaching from a side offset, which requires a higher crossing altitude to maintain obstacle clearance and time to configure for the turn onto final. Crossing at or above 900 feet gives ample time to decelerate, set up for the final approach, and ensure proper alignment. Other options either push the speed or descent rate outside the typical stable range or propose a lower crossing altitude that wouldn’t provide adequate separation or setup time.