NATS, the primary air-navigation service provider in the UK, has received approval from the Civil Aviation Authority (CAA) to reclassify the airspace around Heathrow Airport.
The London controlled-traffic region (CTR) control zone, which is considered to be the busiest piece of airspace in the UK, will change from Class A to Class D from 18 September.
This is in line with the Standardised European Rules of the Air (SERA), which will create consistent airspace classifications across Europe by the end of the year.
Under SERA, visual flight rules (VFR) and special VFR (SVFR) flights will be restricted from entering Class A airspace.
NATS London Terminal Control general manager Paul Haskins said: "We're pleased that our proposal has been accepted by the CAA.
"The change to Class D strikes the best balance between VFR and SVFR access and ensuring a safe and efficient air-traffic environment.
"We will provide access whenever possible, but we would ask VFR and SVFR pilots to remember that this is a very busy piece of airspace and our priority has to be providing a safe service to commercial traffic."
Currently, any VFR or SVFR flights will need to gain clearance to enter the zone, which is always subject to the current work load of air-traffic controllers.
In addition, aircraft will have to carry a transponder, with mode S being mandatory.
As a consequence of the decision, the access to the airspace immediately around Heathrow Airport itself will be restricted, with a Prior Permission Required system in place.
Pilots are being informed that unless they really need to fly inside the 'inner area', they should bypass it.
Image: The inner and outer area of the new London CTR. Photo: courtesy of NATS Limited.