Visual Flight Rules
Visual flight rules make reference to the outside environment both for attitude reference and navigation purposes. If visual reference is lost, for example flying unexpectedly into cloud or reduced visibility, the results may be disastrous. To avoid this, minimum flight visibility and cloud distance should be established and maintained. You may know these as Visual Flight Rules.
Visual Meteorological Conditions (VMC) Minima For Airspace Classes
Each airspace class has VMC minima specified for VFR flights (except for class A where VFR is not permitted). These rules are specified under rules 27 and 28 in the rules of the air.
VMC In Controlled Airspace
Class A. In class A airspace, only Instrument Flight Rules (IFR) flying is permitted. It is the most strictly regulated airspace where pilots must comply with ATC instructions at all times. Aircraft are separated from all other traffic and the users of this airspace are mainly major airlines and business jets.
Class C. Class C airspace in the UK extends from Flight Level (FL) 195 (19,500 feet) to FL 600 (60,000 feet). Both IFR and Visual Flight Rules (VFR) flying is permitted in this airspace but pilots require clearance to enter and must comply with ATC instructions.
Class D. Class D airspace is for IFR and VFR flying. An ATC clearance is needed and compliance with ATC instructions is mandatory. Control areas around aerodromes are typically class D and a speed limit of 250 knots applies if the aircraft is below FL 100 (10,000 feet).
An aerodrome is a location from which flight operations take place such as large commercial airports, small General Aviation airfields and Military Air Bases. The term airport may imply a certain stature (having satisfied certain certification criteria or regulatory requirements) that an aerodrome may not have. So whilst all airports are aerodromes, not all aerodromes are airports.
Class E. Class E airspace is for IFR and VFR use. IFR aircraft require ATC clearance and compliance with ATC instructions is mandatory for separation purposes. VFR traffic does not require clearance to enter class E airspace but must comply with ATC instructions.
VMC Outside Controlled Airspace
Class F. No longer exists in the UK.
Class G. In class G airspace, aircraft may fly when and where they like, subject to a set of simple rules. Although there is no legal requirement to do so, many pilots notify Air Traffic Control of their presence and intentions and pilots take full responsibility for their own safety, although they can ask for help.
Air Traffic Control can provide pilots in Class G with basic flight information service to support their safe flying. An Alerting Service is also provided if necessary to notify appropriate organisations regarding aircraft in need of assistance (e.g. search and rescue).
The semi-circular level system replaces the quadrantal system and brings the UK into line with ICAO standards applied elsewhere around the world. VFR and IFR aircraft are allocated different levels to fly at:
- IFR flights use whole 1000’s of feet (e.g. 1000, 3000 etc. when flying eastbound, and 2000, 4000 etc. when flying westbound)
- VFR flights use the intermediate 500 ft. levels (e.g. 3500, 5500 etc. when flying eastbound and 4500, 6500 when flying westbound)
For VFR flights, compliance with the cruising levels remains good practice but is not mandatory.
VFR at night
VFR at night is permitted in accordance with SERA requirements. Aircraft leaving the vicinity of an aerodrome must maintain 2-way communication with ATC and file a flight plan. The process of ‘booking out’ is still accepted as an alternative method to filing a formal paper or electronic flight plan in certain circumstances. Similarly, abbreviated flight plans filed in flight are still permitted.
There are also more restricting weather minima:
- Minimum cloud ceiling of 1500 ft AMSL
- Flight visibility of 5 km, or 3 km in the case of a helicopter flying outside controlled airspace
- Maintain sight of the surface when flying at 3,000 ft AMSL or below
- Minimum height of 1000 ft (or 2000 ft if over high terrain) above the highest fixed obstacle within 8 km of the aircraft except when taking off or landing
Special VFR (SVFR)
A speed limit of 140 kts applies to aircraft flying under SVFR, which must also comply with the following weather minima:
- Remain clear of cloud and with the surface in sight
- Flight visibility of 1500 m, or 800 m in the case of helicopters
- Maximum indicated airspeed of 140 kt
Rights of way on the ground
Rules on overtaking and giving way are now less specific. Aircraft and vehicles overtaking other aircraft and vehicles can now pass on either the left or the right.
Services Provided Outside Controlled Airspace
There are a few services that can be helpful to all types of pilot flying Outside Of Controlled Airspace. In the UK ATSOCAS are provided by both civil and military Air Traffic Controllers providing a service to commercial airliners, military and private pilots.
The UK’s Air Traffic Services Outside Controlled Airspace offer four types of services.
A Basic Service is intended to offer the pilot maximum autonomy and the avoidance of other traffic is solely the pilot’s responsibility. The controller/ FISO will pass information pertinent to the safe and efficient conduct of flight. This can include weather, changes of serviceability of facilities, conditions at aerodromes and general activity information within a unit’s area of responsibility.
A Traffic Service provides the pilot with surveillance derived traffic information on conflicting aircraft. No De-confliction advice is passed and the pilot is responsible for collision avoidance. A Traffic Service contains the information available in a Basic Service. In addition, controllers provide surveillance derived traffic information on relevant conflicting traffic. Headings and/or levels may also be issued for positioning and/or sequencing.
A De-confliction Service provides the pilot with traffic information and De-confliction advice on conflicting aircraft. However, the avoidance of other aircraft is ultimately the pilot’s responsibility. A De-confliction Service contains the information available in a Basic Service. In addition, controllers shall aim to assist the pilot with his responsibility for the safety of the aircraft by passing traffic information and De-confliction advice. Headings and/or levels will also be issued for positioning, sequencing and/or De-confliction advice.
A Procedural Service is a non-surveillance service in which De-confliction advice is provided against other aircraft in receipt of a Procedural Service from the same controller. The avoidance of other aircraft is the pilot’s responsibility.