Enroute Charts
 

Hi.

Enroute HIGH means Airways in the upper airspace
Enroute LOW means airways in the lower airspace

I just read up to find that Low charts refer to airspace below 18000 feet.Could someone tell me what airspace do the High/Low and High Charts cater to.Also could someone explain the difference between FIR vis-a-vis UIR

HI and LO charts
 

As per ICAO -
Generally LO airspace is the airspace extending up to and including FL 195 -
HI airspace is extending at and above FL 200 (often up to FL 600).
The "18,000 ft" limit is more of a US/Canada definition for airways structure.
xxx
Historically, in ICAO airspace, an airway might be named i.e. A-1 (Amber 1) -
If located between same points. it would be known as UA-1 (Upper-Amber 1).
Aiirways are no longer named by "color" i.e. Amber, Blue, Green, Purple etc...
ICAO now uses Alpha, Bravo, Charlie + number... Too many airways...
xxx
For the US, V "Victor airways" are up to 17,999 feet
At or above 18,000 ft, they are called J "Jet airways" (or HL "Hi-Level" in Canada)
:)
Happy contrails

Thanks BelArg.I got the info on FIR/UIR on
Flight Information Region - Wikipedia, the free encyclopedia incase anyone wants to look up.

High/Lo do all airspace

High does above the countries upper/lower airspace division, if any. This can be anything like 18000, FL195, FL245, FL285 etc. etc

Lo does below the countries upper/lower airspace division, if any. This can be anything like 18000, FL195, FL245, FL285 etc. etc

Lower/Upper ATC may have different divisions that do not conform to these definitions.

Lower/Upper Airways may have different divisions that do not conform to these definitions.

FIR generally up to the limit of the lower airspace. If any. Otherwise entire airspace, sometimes up to UNL.

UIR generally above the upper limit of the FIR.

No FIR/UIR in the US. What the real domestic purposes of these are remains unclear these days as other airspace and ATC sectors most likely do not coincide with domestic FIR/UIR borders.

All clear?

Yup... All Clear threemiles except can you tell me which documents would tell me about the divisions.Would it be in the AIP or something?

Divisions are found in the airspace section of each country's AIP, where the FIRs or/and UIRs are defined laterally and vertically.
They are also found on the front panel of the Jeppesen lower and some upper chart panels or on the charts itself. Varies from region to region.

Cheers! :cool:

Aidu Mod
 

If you are talking UK then this link gives you the answer:

Flight Information Publications (FLIPs) - En-Route

It is the site for the Aeronautical Information Documents Unit of the Ministry of Defence. Just after I noticed your post I happened to be looking for something on that site and noticed this!

Brian Young

upper beyond FL245, lower till FL245.