2022-01-27 - Aircraft Operating at the Vertical Boundary of Controlled Airspace

[VATSIM UK Operations]

Effective 27 January 2022

Historically the UK has always considered aircraft operating at the vertical boundary between Class G (uncontrolled) airspace and controlled airspace to be inside controlled airspace and thus subject to the rules relevant to the airspace classification of the controlled airspace. This meant that pilots were required to fly 100 ft above/below the upper/lower limit of controlled airspace when operating without a clearance.

Example: Previously, a pilot wishing to fly beneath LTMA-1 would have to fly at or below 2400 ft.

Effective today, the UK has aligned itself with ICAO standard practice and removed this difference. At the vertical boundary of airspace the rules of the lower classification apply; this means that the vertical boundary between Class G (uncontrolled) airspace and controlled airspace is considered to be uncontrolled and pilots may fly exactly at the boundary without a clearance and without being considered to have infringed.

Example: Now, a pilot wishing to fly beneath LTMA-1 may fly at exactly 2500 ft.

Although it is still considered best practice to “Take 2” and remain 200 ft clear vertically of controlled airspace, controllers should no longer consider pilots flying at the vertical boundary with uncontrolled airspace to have infringed.

More background and information can be found in UK AIC Y 102/2021.

[VATSIM UK Operations]

Clarifying Note

Re: Use of Levels by Controllers

Following the above changes, MATS Part 1 is to be amended on 28 March 2022 so that Section 1, Chapter 7, Paragraph 9 - Use of Levels by Controllers reads:

Except when aircraft are leaving controlled airspace by descent or climb, controllers should not allocate a level to an aircraft which provides less than 500 ft vertical separation above the lower limit of a control area (including TMAs or airways), or below the upper limit of a control zone or control area (including TMAs) where Class G airspace adjoins vertically. This will provide some vertical separation from aircraft operating at the lower limit, or at the upper limit of controlled airspace.

There are no significant changes to how controllers operate from this change - controllers should still endeavour to provide 500 ft vertical separation against the lower/upper limit of controlled airspace where the adjoining airspace is Class G, as had been UK practice for some time.

However, there will be occasional situations where controllers are required to allocate a level at the boundary between controlled/uncontrolled airspace and it is important to note that the vertical boundary between different classes of airspace now assumes the rules of the lower category of airspace and so, when the boundary is with Class G airspace the boundary is considered uncontrolled airspace.

Because of this, when controllers issues a level at the boundary they must subsequently downgrade the service to an appropriate UK Flight Information Service once the aircraft is level at the boundary because the aircraft will now be operating in Class G airspace. Controllers should aim to provide advance notice of the downgrade.

Example: When vectoring to Bournemouth Runway 26 it may be necessary to descend inbound aircraft to 2000 ft to ensure interception of the glideslope. This is the boundary level between controlled/uncontrolled airspace in this part of the Solent CTA and, as a result of the above changes, is now considered Class G airspace. Thus when level at 2000 ft the controller shall downgrade to either a Traffic or Deconfliction Service. Where possible advance notice should be proved, eg. "NJE5F, when level at 2000 ft, Deconfliction Service."