Semi Circular Rule?

[Bundy]

Hi guys,

Whilst doing my training, we have done a number of short cross country trips in the trike as part of the navigation lessons. I did fly according to the above rule but it seems that very few other aircraft do? What is the general concensess regarding this. On a recent flight past bronkie and back to cullinan everybody seemed to be maintaining roughly 500 to 1000ft AGL.
All flying in different directions so we had to maintain a good look out with regular RT.

I know that Rules are Rules but what should I be doing as sometimes it is damn diffulcult to fly at the "correct" FL due to turbulence as well as the fact that it is far more difficult to spot your waypoints from a higher altitude.

Be interested to hear from you.

[topflight]

If I can remember correcly now....the rule only apply when you are flying in transition altitude(altimeter set to 1013.2hPa QNH) that is 1000ft AGL. Most of us microlighters stay below that....we enjoy the scenery

[RV4ker (RIP)]

Assume you were under TMA (special rules). There it all altitude on Jhb QNH. 6500ft or below any direction (indian country ) or north 7500ft and south 7000ft.

Once outside special rules area's the semi circ rule applies once you are at flight levels usually with ATC. They may however accommodate you at non standard FL's... Below 1500 AGL again is indian country and any alt you want.

[hugo]

From "The Pilots radio handbook" Dietlind Lempp, Edition 13

To ensure vertical seperation, aircraft flying at or above 1500' AGL in uncontrolled airspace have to follow semi-sircular rule.

[CFB Bantam]

Must say that the general situation around Brits area (including Aviatiors and Aeroden) is that the guys stick to this rule, communicate their positions and we keep a good lookout for one another. One thing though is that when someone says he is at 6500' or 7500' you don't always here them say on what QNH setting they are flying on. Personally think that if you hear a fellow aviator crossing you airfield or passing nearby and you hear him broadcast his intentions and he does not say what QNH he is flying on then while you are still taxying or just airborne to give it to him or her

Just my personal opinion

[Tribal Croc]

From "The Pilots radio handbook" Dietlind Lempp, Edition 13

To ensure vertical seperation, aircraft flying at or above 1500' AGL in uncontrolled airspace have to follow semi-sircular rule.

Agree with Hugo

Just a quick one : I heard somewhere that this only applies if you are flying for more than 20nm

[RV4ker (RIP)]

From "The Pilots radio handbook" Dietlind Lempp, Edition 13

To ensure vertical seperation, aircraft flying at or above 1500' AGL in uncontrolled airspace have to follow semi-sircular rule.

Agree with Hugo

Just a quick one : I heard somewhere that this only applies if you are flying for more than 20nm

Nope
More than 20nm makes it a Xcountry and no longer a local flight, but even if less than 20nm the Semi Circ rule applies above 1500.

[RV4ker (RIP)]

From "The Pilots radio handbook" Dietlind Lempp, Edition 13

To ensure vertical seperation, aircraft flying at or above 1500' AGL in uncontrolled airspace have to follow semi-sircular rule.

Agree with Hugo

Just a quick one : I heard somewhere that this only applies if you are flying for more than 20nm

Nope
More than 20nm makes it a Xcountry and no longer a local flight, but even if less than 20nm the Semi Circ rule applies above 1500.

[Bundy]

Thanks guys, yeah I think Ive got it sorted now, will only apply the rule above 1500ft. And yes it is definately got nothing to do with the distance you are flying.

By the way TC good luck with the "arrival" in a few weeks! Better get some good hours in before that event chom! Me thinks you are gonna be a bit busy after that! ha ha

My little Terrorist is now 4 and the grey hairs are definately coming along nicely.

Cheers,

[Loco]

Eish stupid question as soon as you use semi circular rule must your QNH always be set to 1013 hPa?

Reason I ask I've flown over for e.g. KAKT from Rhino @ 6500ft AMSL

KAFT being 4586ft AMSL: 6500ft - 4586ft = 1914ft AGL

It was more than 1500ft AGL...

What was I supposed to do?

Option 1 (> 1500ft AGL):
- Change ALT to 1013 hPa
- Because of semi-circular rule 6500ft is OK (flying west = even + 500ft)
- PS. if I was heading east then I should have been 7500?

Option 2 (< 1500ft AGL):
- Just keep below 6086ft AMSL...

I like to fly as high as possible for safety reasons but it seems very tricky to keep < 1500ft AGL along your whole route...

Cheers
Ant

[Bundy]

Hi Ant, read Rv4ker's (May he rest in peace ) post carefully.

I presume you talking about FAKT (Kitty)? (You mustnt type so fast chom )

When flying in the JHB Special Rules Area, Mag headings 270 to 90 deg (North bound) you are supposed to be at 7500ft. If heading 90 to 270 deg (Southbound) you are supposed to be at 7000ft. However.... If you cannot comply with the above, you can remain 6500ft or below.... ALL ON JHB QNH

Almost all traffic I've come across in the SR areas remains below 6500ft and just broadcasts TIBA.

Nice Link here for you to print:

http://www.cometaviationsupplies.co.za/ ... %20JHB.pdf

Outside controlled airspace, or special rules areas, if you climb above 1500agl, then as I understand it you are required to change to QNE (1013.25) and fly acc to Flight Level and Semi Circ Rule?

Very seldom we go above 1500ft....so dont worry too much.

[Loco]

haha thanks Mr. Bundy for the info, I always struggle to get my head around this, as you can guess I wasn't first in my radio course class, I think I will attend it again

[John.com]

OK, so here's my question: What if two aircraft are flying . . . . one at 181 and one at 359?? Conversely, one at 001 and one at 179??

That's almost head-to-head . . . . but both at the same altitude?

Or am I missing something?

Cheers,

John.com

[Bundy]

I presume we still talking about the SR area?

6500ft and below...that happens often John!

Above that alt...on the headings you posted.. the aircraft routing 181 should be at 7000ft and the other (359) should be at 7500ft according to the SRules area...

Below 6500....communication becomes paramount and it seems there are quite a few pilots who dont know what the PTT is for....the other problem is the amount of different frequencies in the area....Bapsfontein for eg...is right on the boundary of 4 different frequencies!...

[John.com]

I presume we still talking about the SR area?

6500ft and below...that happens often John!

Above that alt...on the headings you posted.. the aircraft routing 181 should be at 7000ft and the other (359) should be at 7500ft according to the SRules area...

Below 6500....communication becomes paramount and it seems there are quite a few pilots who dont know what the PTT is for....the other problem is the amount of different frequencies in the area....Bapsfontein for eg...is right on the boundary of 4 different frequencies!...

Yoh! I think we all need a refresher course on this stuff! Quite confusing, to say the least!

I was actually referring to outside of SRs, where the semi-circle rule applies for flight levels!

Semi Circle Rule.png

If you read my question again with reference to this diagram you will see what I am saying . . . .

Cheers, John.com