SID Waypoint Altitudes

Hi All
I’ve recently decided to get stuck in to learning SID / STAR procedures, having shied away for a few weeks and stuck to manually plotting my ascent and descent routes. I’ve started practising on some short routes like Heathrow > Frankfurt for example.

How do you know when the altitude tag on a SID or STAR waypoint is advisory, or mandated?

The reason I ask… I just programmed and flew a SID out of Heathrow departing SE (the SID is MAY2G). It consists of 2 way points, extending to about 30NM SE, but both waypoints automatically tag 5000 feet. How does this work?
I swear in real life an airliner using that SE route wouldn’t climb and maintain 5000 feet for about 30NM before continuing their climb? Especially given the second of MAY2G’s waypoints (MAY) is almost directly over Gatwick’s RW26L track, so surely this would be a collision risk, the very thing SIDs exist to avoid?

Apologies if I’m being quite stupid here… just trying to understand.

Many thanks,

I believe the SID altitudes might be MSA’s or Minimum Safe Altitudes


They’re not really enforced to my knowledge. I’m a steep climber so I climb way past the limit.


SIDS/STARS are based off real life procedures given by NAVBLUE, nothing is enforced and you can always change them. Its up to you if you want to keep it realistic. And just to clarify no question is stupid :)

Happy Flying


So there are three types of altitudes on a SID/STAR/IAP
At or above
At or below

On Infinite Flight, you can’t tell a difference. You can do 2 things
A: guess/change the altitude. This, as said above is allowed on IF.
2: Look at the plate. You can find there on the internet.

Here is part of the plate for the MAY2G
As there is a line above and below the line, you must be at that altitude.

This here would tell you that you must be at or above 5000 as there is a line below the altitude.
Here, you have to be at or below 5000 as there is a line above the altitude.

A good way to think of it is don’t go where the line is.

Hope that makes sense!


Thank you!

Makes sense, thank you

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You’re welcome! Happy ti help

Adding on @InfiniteFlightDeck‘s great explanation: You can’t say with IF only, but need the corresponding charts.

But as a rule of thumb: Trust your feelings and 90% of restrictions are at or above in my experience.

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Excellent response! I treat all SID altitudes in IF as At or Above altitudes. I only have access to a North America Jeppesen sub and updated foreign charts can be a challenge to find. Safe flying!!!

Yeah, I typically just do it as at or above come to think of it.

IRL, very often when you get an IFR clearance (in the US at least), some controllers will tell you to 'Climb via the SID except maintain XXXX’ where XXXX is usually a different altitude than what’s published. Also, when you contact approach, they sometimes say ‘Cancel altitude/level restrictions,’ so you’re free to climb higher.


That’s a thing in Europe as well from all the videos I saw, as far as I am aware.
Thank you for your IRL input, really interesting!

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