# Why would a pilot need to change their heading when flying through a cold front?

When doing my PPL written review there is a question, simply can't get my head wrapped around the reason why and have searched everywhere. It's definitely a very simple thing, however, I am missing the glue that helps me understand it. Hope someone can help! Thx

When flying through a cold front,_________ in order to maintain track.

This is the correct answer stated:

b) A heading correction to the right is required.

Simply can't get my head around why you would alter heading to the right going either way?

In the Northern Hemisphere, wind usually veers to the right when a cold front passes. If you fly through a cold front, the wind also veers to the right. To maintain a constant track, a correction to the right would be required.

This wind change to the right is the same flying either way through a cold front.

In the Southern Hemisphere the opposite is true. Winds generally back to the left with a cold front passage.

• @OHP As far as the wording of the exam question itself, it's not like you will be out flying one day and have to think to yourself, "Ok... passing frontal boundary... change heading....NOW!" or anything like that. It's just to show that you can mentally conceptualize the wind pattern on each side of the front and correctly state how drift due to wind would be effected based on that understanding. Mar 15, 2022 at 12:57
• Would the caption for that chart be more accurate/general in applicability if, instead of "...surface winds blow from the south," it said something like "...surface winds blow from the equator to the nearest pole"? Mar 15, 2022 at 18:06
• @AndrewMorton I'm no expert on weather or aviation, but since a typical front (and related winds) covers only a tiny fraction of the distance from equator to pole, and since pilots are quite familiar with compass directions, "from the south" seems much simpler and more intuitive than "equator to pole". Mar 15, 2022 at 20:56
• @Federico: The (component of the) wind coming from ahead or behind doesn't affect your course. What matters is that you're either flying into wind coming from your right (if going west to east) or out of wind coming from your left (if going east to west). Either way, the wind is now blowing more from your right (or less from your left, which is the same thing) than before, and a heading correction to the right is needed to maintain your course. Mar 15, 2022 at 21:59
• "If you fly through a cold front, the wind also veers to the right." <-- I'm not a pilot, but I find this phrasing a bit misleading, because "the wind" implies "the same wind". Here's my take: "When flying through a cold front, you transition from winds blowing from your left to winds blowing from your right. So whereas you (presumably) had been compensating with a left-pointing heading correction, you now have to transition to a right-pointing correction." (Also the question not mentioning the hemisphere assumed seems sloppy, but maybe that was considered to have been to big a "hint"?)
– Will
Mar 16, 2022 at 22:11

In the northern hemisphere, if the wind is at your back, the low is on your left.

An air mass is a pile of air stacked up on the surface of the earth. A front is the boundary between two air masses. Piles of air are taller in the middle, and shorter at the edges. Tall piles of air have high pressure in the middle. The edges of air masses have lower pressure. Therefore, fronts always occur in areas of lower pressure (troughs of low pressure). Because of Coriolis force, air circulation around a low pressure are in the northern hemisphere is counter-clockwise.

In actual practice, you fly whatever heading is necessary to maintain your course. The knowledge of the circulation of air can be helpful when planning a trip if your intended path of travel takes you parallel to a front. You would know which side of the front to be on to get a tail wind.

• Appreciate all the insight and all of it contributed to a better mental model and i now thoroughly understand how this works. Thank you.
– OHP
Apr 15, 2022 at 22:43

Adding to Mike's answer to address the part of the question regarding why correct to the right going both directions:

When flying from the cold side through the front, you will go from a tailwind to a crosswind from the right, and you turn right to correct it.

Going the other direction, the crosswind is coming from the left, and you have already turned to the left to correct this. When crossing the front, you no longer need to correct to the left, so you turn to the right.

• Appreciate all the insight and all of it contributed to a better mental model and i now thoroughly understand how this works. Thank you.
– OHP
Apr 15, 2022 at 22:43