Cruising Altitudes

Almost daily I run into [rather, actively have to avoid running into] someone cruising at the same flight level as me.

Only one complaint with that, it just happens to be a significant one: if you’re headed in the opposite direction, there’s no reason you should be at the same flight level.

Here, again, we have people clamor for realism with liveries and which outfit flies where, but eschewing learning anything about actual flight.

So, here, for your learning pleasure, in both graphic and literary form, are the rules regarding proper flight levels depending on your [magnetic] heading:


As you can see, no one headed directly opposite you or me should ever be at the same flight level.

IFR aircraft [this means you if you’re in a commercial airliner above FL180] should be at odd flight levels for headings between 360 and 179; even flight levels for headings between 180 and 359.

It’s not arbitrary. It’s not your favorite flight level. It’s not the service ceiling [side note: the service ceiling is just that, you should not be flying at FL410 every flight, no matter the heading].

VFR aircraft [generally this for GA below FL180; VFR does not, as it is sometimes interpreted in IF just mean "Im in any plane I want but dont want RADAR controllers to tell me what to do; it means legitimate VFR] would add 500 feet to those altitudes (e.g. 6500 westbound or 7500 eastbound).

A note on bullet 3 on the link: Perhaps it’s best an actual pilot weigh in here, but it is my understanding that there is not much non-RVSM airspace remaining, with the advancement of instrumentation, etc. I think for our purposes, it’s fine to just presume that the rules for RVSM airspace are sufficient for IF. (Meaning every 2000 feet for cruising altitudes rather than every 4000. I.e. FL310, FL330, FL350…eastbound and FL300, FL320, FL340 westbound.)

With more and more people leaving their devices earlier and earlier, the least you can do before deserting your flight if you’re going to spend your time begging for realism™ is to set an appropriate cruising altitude so that I’m not flying eastbound at FL330 with some yokel coming westbound at me at the same flight level.

These prescriptions are in place for a reason. Flight levels aren’t arbitrary. And, again, FL410 is not the only acceptable flight level. That’s the service ceiling. Not the target for every flight regardless of heading.


This should be pinned

For a FNF a few weeks ago, was doing DFW-MIA on one of Mark’s flight plans. Another user did the same flight plan but reversed MIA-DFW on the same altitude although I was going East and he was going West but we were both with odd cruise altitudes but his should of been even. We both almost had a direct crash had it not been for me disconnecting AP and banking hard right, stalled the poor 737 but recovered and landed in MIA about an hour later. This was on the Expert Server!

Again, this should be pinned

Warm Regards all,
305 ;)!


No it shouldn’t we already have one that needs to be used

This is more of a simple reminder to pilots to prevent them from doing this again.

Well, I’m not gonna argue about it. Flag if it pleases you, but I doubt many people will see that post from over a year ago and Lord knows what would happen if I necroposted.

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I badly want to necropost it but I also don’t. Too many people have been at the wrong cruise altitude and passed me over the Pacific

It’s a nice reminder. Especially now that pilots are flying longer routes.

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Sweven Neodd. Easiest way to remember. South or West = Even cruising altitude. North or east = Odd cruising altitude. Add 500 is it is VFR.

Good reminder. I would like to avoid hitting other planes flying on the same route in the other direction. The simple rule guarantees 1000’ separation so it is obviously really important!

Read carefully and you see a difference between Mark’s older and Tim’s recent post. For flights over 29000 feet, Mark’s post lists an ODD altitude when flying heading of 180-359 degrees, with a 4000 feet separation. In Tim’s post, the ICAO-IFR circle lists EVEN altitudes for these headings, with a separation of 2000 feet.
Check it out and spot this difference.

Now I’m far from being an expert, but if I understand this correctly, Mark’s post speaks of non-RSVM airspace, which demanded a bigger separation. But non-RSVM airspace is not used widely anymore. I learned that this post from Tim speaks about RSVM airspace, which uses EVEN altitudes for heading 180-359.


Did I see this wrong? Would welcome any of our commercial pilots and/or moderators to comment on this.

What altitudes does IF prescribe…


EDIT: @Mark_Denton can you please help us out here. I can’t believe I’m the only one who is now not sure what procedure to follow for the rightcruise altitude


Thank you for clarifying this. The whole new rule set for over 29000 in non-RVSM airspace was very confusing. Sticking to the NEODD SWEVEN rule is the way to go!

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i use fl3500 for cruising alt

The entire point of this post is that it’s not realistic to use a single cruise altitude.

That makes zero sense on so many levels. In addition to the altitude rules, it means you’re never accounting for wind, temperature, load…anything.


I kindly ask @Mark_Denton to help us out here, and to confirm that indeed your summary is correct.

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Thanks for reminding this theme, guys!
That’s the screenshot I took couple of weeks ago. I even checked if you guys in US have some other rules that I didn’t know… but no…

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See it all the time Oleg and it is very frustrating.

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Mark is simply giving the 4,000 foot increment reference in that post. It is indeed North East Odd, South West Evens. So 360-179 is an odd thousand. 180-359 deg is a even thousand. Now it should be said that it’s the course of the magnetic heading not the actual planes heading.

Example: you have a 20KT Crosswind and you are flying a heading of 010. You could have a course of 350 or 030, or anywhere in between depending on the angle. For IF it’s easy just to keep it as the aircrafts heading. However I’m letting you know that’s it’s actially based of course not heading.

As for the second part of 4,000 above a certain altitude that does hold true for anything that is not RVSM certified. Which most commercial aircraft are now days. In IF we can assume they are since we don’t have any instrument errors to contend with at altitude.

Well I do hope others get it, because I certainly don’t.

I keep using the white circle suggested by Tim, as this I get. Unless somebody tells me Tim has it wrong.

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Just keep using Tims refrence and you’ll be fine.

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RVSM is the world standard. They conflict at FL310, FL350, FL390 @Mark_Denton
Link and image for reference.


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