 | This article needs additional citations for verification .(March 2011) |
Special visual flight rules (also special VFR or SVFR) are a set of aviation regulations under which a pilot may operate an aircraft. It is a special case of operating under visual flight rules (VFR).
The definition for SVFR may be different in different countries, depending on the local aviation regulations.
The ICAO definition of Special VFR flight is a VFR flight cleared by air traffic control to operate within a control zone in meteorological conditions below visual meteorological conditions. [1]
According to Federal Aviation Regulations, SVFR operations can only be conducted in the controlled airspace around an airport where that controlled airspace extends down to the surface (so-called surface area). SVFR can only be conducted below 10,000 feet MSL in such areas. [2] [3]
SVFR at night requires an IFR-equipped aircraft and an IFR-rated pilot in command ("IFR" means Instrument flight rules). In helicopters, there is no minimum flight visibility requirement, or a requirement for an IFR-equipped aircraft or an IFR-rated pilot in command. [2]
| |
Flight under SVFR is only allowed in controlled airspace, and always requires clearance from air traffic control (ATC). [4] It usually happens when the aircraft is inside controlled airspace, and the local weather is less than the minimums required for flight under visual flight rules (VFR) within the airspace in question. [5]
Note that an aircraft might be able to fly under SVFR even in Class A airspace, where instrument flight rules (IFR) flight is the norm. [6]
| |
The aircraft need not necessarily be equipped for flight under IFR, and the aircraft must remain clear of clouds with the surface in sight, and maintain a certain flight visibility minimum (1,500 metres according to ICAO, one statute mile in the US, 1,500 m visibility, in sight of surface and clear of cloud in Europe). The pilot continues to be responsible for obstacle and terrain clearance. [7]
(US) Weather minimums for SVFR are ground visibility of one statute mile (except helicopters) (when ground visibility is not reported, flight visibility of one statute mile) and clear of clouds. Operations must be conducted between sunrise and sunset (except helicopters and in Alaska). Flight under a SVFR clearance at night requires the pilot to have an instrument rating and the aircraft must be IFR equipped. [8]
An example of the use of SVFR is when a flight wishes to leave an airport in controlled airspace, to fly VFR in uncontrolled airspace, when the visibility is below the minimum for VFR flight in the control zone but not below the lower minimum for VFR flight in uncontrolled airspace. SVFR is never offered by Air Traffic Control. It must be requested by the Pilot in Command.
In aviation, instrument flight rules (IFR) is one of two sets of regulations governing all aspects of civil aviation aircraft operations; the other is visual flight rules (VFR).
In aviation, visual flight rules (VFR) are a set of regulations under which a pilot operates an aircraft in weather conditions generally clear enough to allow the pilot to see where the aircraft is going. Specifically, the weather must be better than basic VFR weather minima, i.e., in visual meteorological conditions (VMC), as specified in the rules of the relevant aviation authority. The pilot must be able to operate the aircraft with visual reference to the ground, and by visually avoiding obstructions and other aircraft.
Airspace is the portion of the atmosphere controlled by a country above its territory, including its territorial waters or, more generally, any specific three-dimensional portion of the atmosphere. It is not the same as outer space which is the expanse or space outside the Earth and aerospace which is the general term for Earth's atmosphere and the outer space within the planet's vicinity. History:
In aviation, visual meteorological conditions (VMC) is an aviation flight category in which visual flight rules (VFR) flight is permitted—that is, conditions in which pilots have sufficient visibility to fly the aircraft maintaining visual separation from terrain and other aircraft. They are the opposite of instrument meteorological conditions (IMC). The boundary criteria between IMC and VMC are known as the VMC minima and are defined by: visibility, cloud ceilings, and cloud clearances.
Instrument rating refers to the qualifications that a pilot must have in order to fly under instrument flight rules (IFR). It requires specific training and instruction beyond what is required for a private pilot certificate or commercial pilot certificate, including rules and procedures specific to instrument flying, additional instruction in meteorology, and more intensive training in flight solely by reference to instruments.
Flight plans are documents filed by a pilot or flight dispatcher with the local Air Navigation Service Provider prior to departure which indicate the plane's planned route or flight path. Flight plan format is specified in ICAO Doc 4444. They generally include basic information such as departure and arrival points, estimated time en route, alternate airports in case of bad weather, type of flight, the pilot's information, number of people on board, and information about the aircraft itself. In most countries, flight plans are required for flights under IFR, but may be optional for flying VFR unless crossing international borders. Flight plans are highly recommended, especially when flying over inhospitable areas such as water, as they provide a way of alerting rescuers if the flight is overdue. In the United States and Canada, when an aircraft is crossing the Air Defense Identification Zone (ADIZ), either an IFR or a special type of VFR flight plan called a DVFR flight plan must be filed. For IFR flights, flight plans are used by air traffic control to initiate tracking and routing services. For VFR flights, their only purpose is to provide needed information should search and rescue operations be required, or for use by air traffic control when flying in a "Special Flight Rules Area."
In general aviation, scud running is a practice in which pilots lower their altitude to avoid clouds or instrument meteorological conditions (IMC). The goal of scud running is to stay clear of weather to continue flying with visual, rather than instrument, references. This practice is widely accepted to be dangerous, and has led to death in many cases from pilots flying into terrain or obstacles, such as masts and towers, normally referred to as controlled flight into terrain, or CFIT; however, even instrument-rated pilots sometimes elect to take the risk to avoid icing or embedded thunderstorms in cloud, or in situations where the minimum instrument altitudes are too high for their aircraft.
The world's navigable airspace is divided into three-dimensional segments, each of which is assigned to a specific class. Most nations adhere to the classification specified by the International Civil Aviation Organization (ICAO) and described below, though they might use only some of the classes defined below, and significantly alter the exact rules and requirements. Similarly, individual nations may also designate special use airspace (SUA) with further rules for reasons of national security or safety.
In aviation, instrument meteorological conditions (IMC) are weather conditions that require pilots to fly primarily by reference to flight instruments, and therefore under instrument flight rules (IFR), as opposed to flying by outside visual references under visual flight rules (VFR). Typically, this means flying in cloud or poor weather, where little or nothing can be seen or recognised when looking out of the window. Simulated IMC can be achieved for training purposes by wearing view-limiting devices, which restrict outside vision and force the trainee to rely on instrument indications only.
An instrument rating is an authorization required for a pilot to fly under instrument flight rules (IFR). In the United States, the rating is issued by the Federal Aviation Administration.
In aviation, an instrument approach or instrument approach procedure (IAP) is a series of predetermined maneuvers for the orderly transfer of an aircraft operating under instrument flight rules from the beginning of the initial approach to a landing, or to a point from which a landing may be made visually. These approaches are approved in the European Union by EASA and the respective country authorities and in the United States by the FAA or the United States Department of Defense for the military. The ICAO defines an instrument approach as "a series of predetermined maneuvers by reference to flight instruments with specific protection from obstacles from the initial approach fix, or where applicable, from the beginning of a defined arrival route to a point from which a landing can be completed and thereafter, if landing is not completed, to a position at which holding or en route obstacle clearance criteria apply."
Allegheny Airlines Flight 853 was a regularly scheduled Allegheny Airlines flight from Boston, Massachusetts, to St. Louis, Missouri, with stops in Baltimore, Maryland, Cincinnati, Ohio, and Indianapolis, Indiana. On September 9, 1969, the aircraft serving the flight, a McDonnell Douglas DC-9, collided in mid-air with a Piper PA-28 light aircraft near Fairland, Indiana. The DC-9 was carrying 78 passengers and 4 crew members, and the Piper was leased to a student pilot on a solo cross-country flight. All 83 occupants of both aircraft were killed in the accident and both aircraft were destroyed.
VFR over-the-top (OTT) refers to flying over top of clouds in visual flight, rather than with reference to instruments. This is usually done for brief amount of time to avoid weather or turbulence.
The East River Special Flight Rules Area (SFRA), formally known as the East River class-B exclusion, is a section of airspace above the East River in New York City in which flight is permitted under visual flight rules (VFR). Formerly, this could be done without being in contact with air traffic control. Pilots operating within the SFRA are expected to self-announce on a designated frequency of 123.075 MHz, and to maintain appropriate separation visually.
The United States airspace system's classification scheme is intended to maximize pilot flexibility within acceptable levels of risk appropriate to the type of operation and traffic density within that class of airspace – in particular to provide separation and active control in areas of dense or high-speed flight operations.
In air traffic control, separation is the name for the concept of keeping an aircraft outside a minimum distance from another aircraft to reduce the risk of those aircraft colliding, as well as prevent accidents due to secondary factors, such as wake turbulence. Separation can also apply to terrain, obstacles, and controlled airspace, wherein an aircraft must stay at a minimum distance from a block of airspace; as an example, all aircraft must be approved by the controller who "owns" the airspace before the aircraft is approved to enter that sector.
In United States aviation VFR-on-top is defined as air traffic control authorization for an aircraft operating under instrument flight rules (IFR) to do so in visual meteorological conditions (VMC) at any appropriate visual flight rules (VFR) altitude. A pilot receiving this authorization must comply with the VFR visibility, distance from cloud criteria, and the minimum IFR altitudes. The use of this term does not relieve controllers of their responsibility to separate aircraft in Class B and Class C airspace or TRSAs.
In aviation, a visual approach is an approach to a runway at an airport conducted under instrument flight rules (IFR) but where the pilot proceeds by visual reference and clear of clouds to the airport. The pilot must at all times have either the airport or the preceding aircraft in sight. This approach must be authorized and under the control of the appropriate air traffic control (ATC) facility. The International Civil Aviation Organization (ICAO) definition adds that the visual approach can commence when "either part or all of an instrument approach is not completed", varying only slightly from the Federal Aviation Administration regulation and is essentially identical.
A contact approach is an approach available to aircraft operating on an instrument flight rules (IFR) flight plan, where the pilot may deviate from the published instrument approach procedure (IAP) and proceed to the destination airport by visual reference to the surface. It is similar to a visual approach, except that the pilot is not required to have the destination airport nor the preceding aircraft in sight at all times during the approach, and the visibility requirements are less stringent.
On October 25, 1991, a Bell 206 carrying rock music concert promoter Bill Graham, his girlfriend Melissa Gold, and pilot Steve Kahn crashed into a transmission tower west of Vallejo, California, killing everyone on board. The cause of the accident was determined to be the pilot's intentional flight into known adverse weather conditions.