CTA base level, do you need a clearance?

[Ready Immediate]

I agree with jangler909. In OZ if you are at a level which is the boundary of two airspace blocks then you are in the lower class of airpace. Assuming the lower class in this example is G then no clearance required.

RI

[chevvron]

This first came up in about '75 or '76 when the LTMA base around the London area became 2500ft; we were told categorically (by the then fledgling CAA)that the base level (2500) WAS regulated airspace, hence everyone flys 100ft below it. It's best to anyway; if you fly at the base level, aircraft 500ft above the base would detect your transponder within their TCAS RA envelope.

[Turn It Off]

Originally Posted by anotherthing

at the moment with our watch it's aobut 1 and a half hours on console with 29 minutes off, we are a tad tight on personnel; that said you can make time if you engineer an airprox

thats better than the 2hrs 1 minute on 29 mins off we get.

[anotherthing]

Turn it off

Fair point - I assume yours is a 2 hour position, whereas ours are one and a half hour positions mostly - so although we do half an hour less, it seems manpower wise we are in the same boat i.e. we are stretched to having to do the maximum most of the time.

It's all very well for SRG and the management to say a position is either a one and a half or two hour position - but have they reakised how tiring it is to do that continuously??

[Talkdownman]

Originally Posted by chevvron

if you fly at the base level, aircraft 500ft above the base would detect your transponder within their TCAS RA envelope.

Our descents to 3 frequently get RA's from 2 point 4's (especially with Swiss RJ's) so some of us delay the descent in order to minimise such RAs and associated reporting nause. It has always seemed daft to me that we vertically separate consenting adults by standard separation then condone less than standard from unpredictable unknown traffic with unknown capability. 'Deemed separated', we are informed. 'Duty of Care' from the procedures planners, no doubt......

[eyeinthesky]

Quote
so some of us delay the descent in order to minimise such RAs and associated reporting nause
Unquote

Excellent!!! that's what's known as defensive controlling' and makes sense.

Those people who give descent to 3A on top of unknown traffic outside CAS at 2.4A 'because they can' are setting themselves up for an RA or loss of separation if the guy pops up 200ft. Why risk it? Do the aircraft land any quicker?

[fireflybob]

Believe in the UK you can cross at the base level of an airway at 90 degrees if base level defined as a Flight Level.

[Talkdownman]

Keep up, Bob, keep up!

[CAP493]

Do the aircraft land any quicker?

No - but in many areas of UK terminal (controlled) airspace, because the design is so poor in respect of IAPs and the vertical dimensions of the associated CAS, this methodology can result in an approach that's not stabilised with aircraft attempting to capture the glide-path from well above. It only works well for aircraft such as the 146 series, Dash-8, Dornier 328, etc., i.e. those types where the flight-deck can adopt 'STOL' handling technique.

Those people who give descent to 3A on top of unknown traffic outside CAS at 2.4A 'because they can' are setting themselves up for an RA or loss of separation if the guy pops up 200ft

Unfortunately, if the FIR traffic is wearing a conspicuity squawk, there's no guarantee that the Mode-C is correct and so the altitide of say 2400' could be totally incorrect; and in any event, it cannot be used by ATC to provided 'standard' i.e. 1000 feet vertical separation (the separation used is a 'deemed separation' against traffic outside CAS [an ICAO concept that the UK with others, adopts]) - under RAS i.e. in Class G the requirement is (I believe) 3000 feet, which would mean you actually stopping your descent at 5400 feet if the same criteria were required for traffic inside CAS against traffic outside.

Whoever said ATC is a exact science...