To reach point Y on schedule, what is the required indicated airspeed if Point X is crossed at 1550?

To determine the required indicated airspeed to reach Point Y on schedule after crossing Point X at a specific time (1550), it's essential to consider the relationship between speed, distance, and time.

When you need to make up time or maintain a schedule, the indicated airspeed must be calculated based on the distance remaining to Point Y and the time available to cover that distance. Typically, this would involve using the formula:

Speed = Distance / Time

If the flight plan indicates that you are scheduled to arrive at Point Y at a certain time and you cross Point X at 1550, you would calculate how much time you have available to reach Point Y and the distance to be covered from Point X to Point Y.

In this scenario, if option C provides you with the right number for indicated airspeed enabling you to cover the remaining distance within the required timeframe, it implies that this speed is optimum given the constraints of your flight plan. Thus, reaching Point Y on time would demand maintaining an indicated airspeed of 143 knots from Point X. This speed aligns with your needs to ensure punctual arrival at Point Y.