The national airspace system divides all airspace into different levels. They are classified according to certain needs, functions, and levels of regulation. There are restrictions and regulations associated with each level of airspace. However, all civil aviation aircraft must follow Visual flight rules (VFR) and Instrument flight rules (IFR).

They were created to ensure the safety and efficiency of air traffic in various weather conditions. Rules are also called air traffic standardization and safety categories. Such sets of flight rules allow pilots and controllers to work under the same requirements and ensure effective coordination in the airspace.

Сontrol of the aircraft under good weather conditions and sufficient visibility

  • VFR apply when flight conditions are favorable. The pilot must have a clear view of the surrounding space in order to adjust the altitude of the aircraft. Orientation is carried out on the earth’s surface, avoiding obstacles of the type of buildings and features of the terrain and other planes.
  • The weather should be better than the main VFR weather lows. That is, within the framework of visual meteorological conditions, which are specified in the rules of the relevant aviation authority. Also, governing bodies set special requirements for flights to ensure safety. This includes minimum visibility and cloud cover to ensure that aircraft can be seen from a sufficient distance.
  • Under visual meteorological conditions, the minimums such as visibility range, distance from clouds, or cloudiness requirements to be maintained over the ground may vary from jurisdiction to jurisdiction. Also, the indicators may vary due to the airspace in which the aircraft operates.
  • The generally accepted daytime minimum under VFR for most airspace is 3 statute miles of flight visibility and a cloud clearance of 500 feet below, 1000 feet above, and 2000 feet horizontally.
  • Flights under VFR may be permitted at night, but this only applies to certain countries. This involves more restrictive conditions, such as maintaining minimum safe altitudes and additional training.
  • The VFR place responsibility for keeping a distance from other aircraft on the pilot. The controller does not participate in air traffic control and does not assign a route or altitude. The exception is the situation when the aircraft pilot is outside B/C/D airspace over the territory of the United States, Canada, and Australia. He can submit a request to receive a traffic advisory from the dispatcher.
  • Due to the limited communication and navigation equipment required for flights under visual rules, the plane may be restricted in certain operations. There may be restrictions on when and how long an aircraft is allowed to be in controlled airspace.
  • They also outline such a subcategory as Special VFR. This is an air traffic controller’s clearance to fly under special VFR in a control area in meteorological conditions that do not meet the minimum visual meteorological conditions.

The United States VFR cruise altitude rules

In the United States, there are designated VFR for cruising altitudes. This covers aircraft heading above 3,000 feet above sea level but below 18,000 feet mean sea level. However, unofficially, these rules are used at all levels of cruising flight.

On a magnetic course of 0-179 degrees, the planes should fly at an odd thousand feet MSL at an altitude of +500 feet. At 180-359 degrees, the pilot has to fly the plane at an even height of one thousand feet MSL +500 feet.

Сontrol of the aircraft according to the indicators of navigation devices

  1. IFR are another set of rules that are followed in the operation of civil aviation aircraft. The US Federal Aviation Administration has come up with these rules and regulations for conditions where flying by external visual guidance is unsafe. The main task of these rules is to implement safe echeloning.
  2. In uncontrolled airspace, air traffic control directs planes according to IFR to a safe distance from obstacles and other aircraft. Also tracks planes on radar or through position reports in areas where radar coverage is unavailable. The reports take the form of voice radio broadcasts. In the United States, aircraft operating under IFR are required to report their position only when flying over the ocean.
  3. Special procedures allow planes under IFR to safely complete each stage of the flight. These procedures determine how the pilot should react, even in the event of a total radio failure and loss of contact with the air traffic control regulation, including the expected course and altitude of the aircraft.
  4. IFR for pilots working in controlled airspace are permitted only after receiving confirmation from air traffic control for each part of the flight. A mandatory part of the contract is a specified limit, which is the maximum distance that the aircraft can fly without a new permit.
  5. All details of the departure are prescribed in the IFR permit issued by the controller before takeoff. A departure clearance may contain a designated course, one or more waypoints, and an initial flight altitude. The clearance may also specify a departure procedure or simply a standard departure under IFR to be followed.
  6. En-route flight is described by charts that show navigation aids, waypoints, and standard routes called airways. Aircraft with suitable navigation equipment such as GPS are also often authorized to fly a direct route, where only the destination or a few navigational waypoints are used to describe the route the flight will follow. IFR navigation is also provided by ground and satellite systems such as DME/VOR, NDB, and GPS/GNSS. Air traffic control can provide pilots with certain directions (“radar vectors”). However, radar vectors are usually reserved for air traffic control to sequence aircraft for approach or takeoff to cruise level.
  7. When flying under IFR, visibility requirements as such do not have a specific minimum indicator. Flying through clouds in conditions of zero visibility is considered legal and safe. However, there are minimum weather conditions required for an aircraft to take off or land. Depending on the type of operation, the type of navigational aids available, the location and height of terrain and obstacles near the airport, the equipment on board, and the qualifications of the crew, they may vary.

Requirements of IFR

Not every pilot will be able to fly according to the rules of instrument flight. He must have appropriate qualifications and gain some flight experience.

In the United States, to file and fly under the IFR, a pilot must have an instrument rating and have completed six instrument landings, holding and intercept procedures, and continued use of navigational aids within the previous six months.

Instrument landing practice can be performed in meteorological conditions using instruments. Also, practice may be expected in visual meteorological conditions, but under such conditions, a safety pilot will be present.

Major differences

Flying airplane
  • Anyone who has completed training and received a private pilot license can fly under the VFR. After all, this is a basic set of rules by which a pilot is taught to fly.
  • VFR and IFR are contained in Part 91. It has no restrictions on where and when a pilot can fly under IFR. However, there are many restrictions for pilots under VFR. They cannot operate in clouds or poor visibility.
  • In relatively clear weather conditions, the aircraft can be controlled solely by external visual cues, such as the horizon for orientation support, nearby buildings and terrain features for navigation, and other planes for echelon support. That is, it is the regulation of the aircraft according to the rules of visual flight. Known as the most common mode of operation for small planes. It is safe to fly under VFR only when these external landmarks can be seen from a sufficient distance. When flying through or above clouds, or during fog, rain, dust, or similar low weather conditions, these links may be closed. Therefore, cloud cover and in-flight visibility are the most important variables for safe operation during all phases of flight. It is forbidden to work too close to the clouds because only fast planes that fly according to the instrument flight rules can enter and leave these clouds.
  • Any aircraft operating under VFR must have the required equipment on board as described in Part 91.205 of the VFR. Those flying under IFR must have certain equipment and meet the minimum requirements specified in Part 91.205 but subsection (d). Pilots under VFR may use cockpit instruments as aids to navigation and orientation but are not required to.
  • Specific requirements also depend on the class of airspace and the altitude at which the pilot is operating. But in general, VFR require pilots to stay at least 500 feet below, 1,000 feet above, or 2,000 feet horizontally from all clouds. They are also rarely capable of operating in visibility of less than three statute miles, although there are a few exceptions.
  • Іn Class A airspace, only flights under the IFR are allowed. Class A is everywhere at high altitudes, so anywhere over the United States above 18,000 feet MSL. Below, the use of VFR is allowed, but not the other way around.

What is safer?

Any experienced pilot should be able to fly an airplane both according to VFR and IFR. If the flight is in good weather conditions, in a familiar area, for a short distance, and the person who will fly the plane is experienced, then it is possible to enjoy the flight according to VFR. However, it is much safer to additionally insure navigation devices and the dispatcher.

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