Multi-Engine: Zero-Sideslip
The zero-sideslip is necessary for a pilot to maintain control of an aircraft and have the greatest climb performance during an engine failure in a twin.
Aerodynamics | February 10, 2022
Special VFR (SVFR), otherwise known as Special VFR operations, is a specific clearance that allows a pilot to conduct VFR flight in controlled airspace with current meteorological conditions being less than basic VFR weather minimums.
Special VFR is allowed, or authorized, only within the lateral boundaries of Class B, Class C, Class D, or Class E surface areas below 10,000ft at any location that is not prohibited by 14 CFR Part 91 Appendix D. To fly under Special VFR at an airport listed in appendix D it is required that the operation be conducted in anything other than a fixed-wing aircraft( such as a helicopter), or an exemption has been granted and an associated Letter Of Agreement established.
Pilots should be aware that ATC has the right to deny a Special VFR clearance depending on workload or other operational considerations.
During normal operations under VFR, a pilot must maintain at least the basic VFR weather minimums for the airspace being flown in as listed under Part 91.155.
A Special VFR clearance allows a pilot to operate under VFR while the current weather is below the basic VFR weather minimums for a given airspace. The clearance must be obtained prior to operating within a Class B, Class C, Class D, or Class E surface area when the weather is less than the minimums required for VFR flight.
According to Part 91.157, if the request to operate under Special VFR is approved by air traffic control, the pilots' new weather minimum is reduced to the following:
Helicopters must only remain clear of clouds and are allowed to conduct special VFR operations in Class B, Class C, Class D, and Class E surface areas with less than 1 statute mile visibility.
For a pilot to legally be able to operate under a Special VFR clearance they must hold at least a private pilot certificate. Student, Recreational, and Sport pilots are not allowed to request a Special VFR clearance. However, a pilot that wishes to operate under a Special VFR clearance at night must hold an instrument rating and be instrument current.
For an aircraft to operate under a Special VFR during the day it must be equipped with at least the standard equipment that would generally be required for day VFR operations.
Except for helicopters, for an aircraft to legally be able to operate under a Special VFR clearance between sunset and sunrise (or in Alaska, when the sun is 6 degrees or more below the horizon) it must be equipped to operate under IFR.
To take off or land an aircraft ( other than a helicopter) under special VFR, the following must be true:
For a pilot to use flight visibility of 1 statute mile instead of a ground visibility of 1 statute mile, the flight must be conducted under part 91, and the aircraft has to be located at a satellite airport that does not have weather reporting capabilities.
Since flight visibility is subjective, the FAA defines flight visibility for special VFR as the "visibility from the cockpit of an aircraft in takeoff position."
When a control tower is located at a Class B, Class C, or Class D surface area a pilot should make a request for a special VFR clearance to the tower. Requests to operate under Special VFR in a Class E surface area should be obtained from the nearest Tower, Flight Service Station, or Center controller.
Pilot arriving or departing from an uncontrolled airport that has a weather broadcast (ASOS/AWSS/AWOS) should monitor the weather broadcast frequency for their airport, and notify the controller that they have the "one-minute-weather" along with their intentions before operations within Class B, Class C, Class D, or Class E surface areas.
The FAA does not require a pilot to complete a flight plan with the request for a clearance, but a pilot should provide their intentions in sufficient detail to enable air traffic control to fit their flight into the traffic flow.
If a Special VFR clearance is provided, it is only effective within the Class B, Class C, Class D, or Class E surface area.
Controllers may request a pilot to fly at or below a certain altitude to avoid traffic conflicts, but the altitude requested will at a minimum allow flight at or above the minimum safe altitude. Radar Vectors may be provided if necessary or on pilot request.
Once a pilot exits the Class B, Class C, Class D, or Class E surface area air traffic control will no longer provide separation on a special VFR clearance.
Air traffic control will only allow Special VFR flights if arriving and departing IFR traffic is not delayed.
However, the priority afforded to IFR aircraft over Special VFR traffic is not intended to be so rigidly applied that the end result is an inefficient use of the controller's airspace. The controller has the prerogative of permitting completion of a Special VFR operation already in progress when an IFR aircraft becomes a factor if better overall efficiency is the end result.
For example, A Special VFR aircraft has been cleared to enter a Class B, Class C, Class D, or Class E surface area, and subsequently, an IFR aircraft is ready to depart or is in position to begin an approach. Less overall delay might accrue to the IFR aircraft if the SVFR aircraft can proceed to the airport and land, rather than leave a Class B, Class C, Class D, or Class E surface area or be repositioned to provide IFR priority.
The following situation may also apply, A Special VFR aircraft is number one for takeoff and located in such a position that the number two aircraft, an IFR flight, cannot taxi past to gain access to the runway. Less overall delay might accrue to the IFR aircraft by releasing the SVFR departure rather than by having the aircraft taxi down the runway to a turnoff point so the IFR aircraft could be released first.
If air traffic control deems that a Special VFR clearance may result in delays for IFR traffic, the controller will inform the Special VFR traffic of the anticipated delay in terms of expected minutes of delay. However, an Expect Further Clearance (EFC) time or expected departure time would not be provided.
Phraseology: EXPECT (number) MINUTES DELAY, (additional instructions as necessary).
Air Traffic Control will provide non-radar or visual separation between:
Due to the requirements of a Special VFR fixed-wing aircraft to maintain 1-mile flight visibility and remain clear of clouds, radar separation can not be used during Special VFR operations.
However, radar vectors may be used while operating under special VFR only within Class B, Class C, Class D, or Class E surface areas to expedite the entrance, exit, and transition of special VFR fixed-wing aircraft through the appropriate surface area.
Air traffic control is allowed to provide IFR separation in addition to non-radar, and visual separation between:
Alternate SVFR helicopter separation minima may be established when warranted by the volume and/or complexity of local helicopter operations.
A Letter of Agreement (LOA) must be established with the helicopter operator in order to operate with alternate SVFR helicopter minima. The LOA must specify, as a minimum, that SVFR helicopters are to maintain visual reference to the surface and adhere to the following aircraft separation minima:
The 1-mile requirement between SVFR helicopters may be reduced to a separation of 200ft if:
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