Special VFR (SVFR) allows non-IFR flights to be conducted within Class A airspace, or within Class D airspace when weather conditions are less than VMC. Flight visibility must still be at least 1,500m.
A Special VFR clearance does not absolve the pilot from the relevant Low Flying Rule other than the ‘1000ft’ element of Rule 5.
The requirements for special VFR are:
- Daytime only
- Clear of cloud with the surface in sight
- Minimum flight visibility at least 1,500m
- Airspeed of 140kts or less
It is still the pilots responsibility to maintain terrain clearance that they could glide clear in the event of an engine failure.
A Control Zone is airspace of defined dimensions within which all air traffic is controlled.
If a PPL holder receives a Special VFR clearance to enter a control zone (CTR) but, before entering the CTR, finds that he can no longer receive or transmit RT messages, he must remain clear of the CTR.
Instrument Flight Rules (IFR) are rules which allow properly equipped aircraft to be flown under instrument meteorological conditions (IMC).