What FL do you use, when you fly from A in the north to B in the south, and B is just down from A?

Question

I mean, let's imagine a flight from Detoit to Atlanta. So, from waypoint 1 to waypoint 2, you fly a heading of 170, from WP2 to WP3, you fly 190.... So you always fly from odd (so ood FL) to even (even FL). What FL do you then actually fly? Always change your FL depending your course?

Answer 1

You file a flight level appropriate to your initial direction of cruise flight.  In all reality, use flight levels for planning purposes.  More times than not, you'll follow the direction of flight altitude rules, but if you are in a radar environment (which you are on any domestic flight in the flight levels), you fly whatever ATC tells you to fly.  They can (and regularly do) override the cruise altitude rules.  So if you change direction, ATC may say "we need you at an altitude appropriate for direction of flight - do you want to go up or down?" or you may just stay exactly where you started.

Answer 2

I fly in Europe so I don't know so much the American rules but I understand the sense of your question. Only that flying at those levels, here you would be flying IFR and as such, you should stay at the level the radar control cleared you to. In Europe, flying east or west VFR, we also follow the rule of even number to the west as uneven to the east. I would then fly westward to say, 4,500 ft (VFR is supposed to be at FL + 500 ft since IFR is at FL). In your question, you'd like to know if I was to change altitude when flying first mag heading 170, then 190. I guess I would be flying to an altitude that suits my flight best considering wind, terrain and clouds. That's what VFR flying is; see and be seen. The half circle rule is only an aid to navigation hoping that you'll meet least possible traffic coming toward you. But ... in my own experience, collisions avoidance is mostly for traffic coming from the side. It's a practice that one tend to ignore, especially when flying long distance, but one should always look left to right, regulary.

Answer 3

Flight levels are base on heading and flight rules.

Odd altitudes for North and East - From 000 to 179.

Even from 180 to 360.

Under visual flight rules, you fly at 500 feet above the odd or even altutude.  For instance, from Detroit to Atlanta, you'd fly at 1500, 3500, 5500, 7500, 9500, 11500, etc, under VFR or visual flight rules.

Under Instrument Flight Rules, or IFR, you'd fly at 1000, 3000, 5000, 7000, 9000, 11000, etc., on that same course.

That keeps planes 500 feet above or below each other, and planes heading in opposite directions at least 1000 feet apart vertically.

I hope that makes sense, and answers your question.

Answer 4

In the US "....under IFR....In controlled airspace....maintain the .....flight level assigned....by ATC."

(Under IFR, the even/odd rule applies in uncontrolled airspace).