Learning to navigate

It has been a short week when it comes to sitting in class. We had Monday off and since me and another student had our introductory flights on Thursday, I also had Friday off, while the rest flew their flights. But we had time to finish Air Law, start with Principles of Flight and continue with Navigation as well as do two exams, on Communications and General Safety, which we all aced.

I mentioned after the first day of school that I would get back to the Jeppesen CR-3 circular computer we got, once I learn to use it. It looks quite complicated, but it’s a very handy tool once you get the hang of it. Honestly I find it fun! The CR-3 has two sides, the calculator side and the wind side.

The calculator side.

On the calculator side you can for example convert units (kg, lb, ft, km, nm, °C, °F etc.), do basic multiplications and divisions, calculate fuel consumption, time, speed, distance and calculate your real altitude in different outside temperatures.

On the wind side you can calculate wind components such as headwind/tailwind and right/left crosswind. Once you know them, you can figure out the wind correction angle to calculate the heading you need to fly towards, so that you will end up where you plan to despite the wind. In other words, the wind will always blow the plane from its’ heading to its’ track. Therefore you need to steer into the wind on a heading that will allow the plane drift to the right track that connects the departing point and the destination. (An aircraft’s heading is the direction that the aircraft’s nose is pointing.)

The wind side.

By calculating the wind components it is also possible to figure out the ground speed of the plane. The plane’s airspeed indicator shows the plane’s speed relative to the air mass through which it is flying. Ground speed indicates the plane’s speed relative to the ground. Ground speed is used to calculate the flight time between two cities. To calculate the ground speed you need to know the headwind/tailwind component. Say the plane is flying at the speed of 95 kt and there’s a tailwind of 25 kt. The plane will move at the speed of 120 kt relative to the ground. The airspeed indicator will still show 95 kt. In case of headwind 25 kt, the airspeed will still show 95 kt, but the plane will only move at the speed of 70 kt relative to the ground. This explains why it sometimes takes longer to reach your holiday destination.

We started planning a flight from Malmi (EFHF) to Turku (EFTU) this week, but didn’t have time to finish it. It involved a map and it was fun! I will get back to the EFHF-EFTU trip next time once the plan is finished.

This coming week we have exams on Air Law and Meteorology, which continues for another full day this week before the exam. It’s looking like a full and busy week with Navigation, Principles of Flight, Communications, Meteorology and a new subject Flight Performance and Planning.


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