Dear all,

Hi everyone! This is my first time posting questions on the forum, so please forgive me and let me know if I have done something wrong here:lol:

In RPL/PPL Study Guide volume I page 80, I am advised to consider the relationship between climb performance and wind as "a box of air". When there is headwind, the whole "box" in which the aircraft is climbing will move downwind. Therefore the rate of climb is not affected at all.

However, I am confused about the difference in angle of climb. Since the box has moved downwind as shown in the lower figure, it seems that the aircraft climbs from a different origin. May I confirm whether it means that if the origin remains unchanged while the rate of climb is not affected, the climb path needs to be steeper in order to achieve the same height in a given ground distance?

In addition, may I know what the observer means? This is the first time I heard about this so I am very curious about it.

Thanks so much!

Anson

'The observer' refers to a person standing on the ground and observing the climb path from his/her point of view. However, if the climb is performed in a headwind, the 'box' of air in which the aircraft is climbing is moving back towards the ground position at which the climb commenced (what you have called the origin).

Even though it takes the same TIME to climb to a given height (RATE of climb), the ground distance covered from the origin to the point where the given height is achieved is reduced in a headwind. Therefore, to the observer, the ANGLE of climb is steeper.

In the case of a tailwind, the distance from the origin to the point where the given height is reached is greater because the 'box' of air containing the climbing aircraft is moving away from the origin. So the ANGLE of climb is shallower.

When it comes to avoiding obstacles or terrain during the climb, it is the 'observed' angle of climb that keeps you safe.

I understood that! Thank you so much Bob.