VFR, IFR and VMC minima

Read the VMC table

Altitude band, airspace class and terrain height all matter.

The ordinary SERA minima

At and above 10,000 ft AMSL, ordinary VMC requires 8 km flight visibility and 1,500 m horizontal/1,000 ft vertical cloud separation. Below 10,000 ft the ordinary visibility is 5 km with the same cloud distances. Where transition altitude is below 10,000 ft, FL100 is used in place of the 10,000-ft boundary. Class A’s table entry is guidance and does not permit VFR there.

In Class F/G at and below the higher of 3,000 ft AMSL or 1,000 ft above terrain, the ordinary requirement is 5 km, clear of cloud and with the surface in sight. Reduced visibility down to 1,500 m for specified low-speed/low-encounter circumstances requires competent-authority prescription; it is not an automatic pilot-selected reduction. Helicopter provisions are different.

A visibility number alone is insufficient

Class C at 2,500 ft still uses 1,500 m horizontal and 1,000 ft vertical cloud separation; the low-level clear-of-cloud rule applies to F/G, not every class. At high terrain, compare altitude with the higher boundary rather than blindly using 3,000 ft.

Night VFR has additional conditions, including a flight plan when leaving the vicinity, appropriate communication, a normally 1,500-ft ceiling and surface-in-sight requirements in the specified low-level band. National higher minima and published restrictions can apply. Ordinary VFR is not permitted above FL195 except by the specified authorisation, and not at transonic or supersonic speed.

Special VFR is a clearance in a CTR

An exception has conditions and a geographical scope.

Conditions for the pilot

Special VFR requires an ATC clearance within a control zone. Unless the competent authority permits otherwise, it is by day. The pilot remains clear of cloud and with the surface in sight, with at least 1,500 m flight visibility for an aeroplane, and at 140 kt IAS or less to provide observation time. Helicopters have a separate 800 m minimum.

ATC’s ordinary conditions include ground visibility not less than 1,500 m for aeroplanes and ceiling not less than 600 ft, with the specified helicopter and special-case provisions. Ground visibility and flight visibility are different observations. A forecast alone is not proof of either at the time of operation.

Do not expand the exception

Special VFR does not authorise an unqualified pilot to enter IMC, leave the CTR in sub-VMC conditions or ignore terrain. ATC separates special VFR from IFR and, unless a prescribed exception applies, from other special VFR flights.

A pilot outside the CTR who cannot remain in ordinary VMC needs a lawful plan to reach or remain within the clearance’s scope. “Request special VFR” is not a universal escape from deteriorating weather along an uncontrolled route.

IFR: qualification, level and change of rules

IFR responsibilities continue even when the sky becomes clear.

Minimum levels and equipment

IFR requires suitable instruments and navigation equipment and the pilot’s applicable instrument privileges. Except for take-off/landing or specifically authorised cases, use the State’s minimum flight altitude. Where none is established, the ordinary minimum is 2,000 ft above the highest obstacle within 8 km of estimated position over high terrain or mountainous areas, and 1,000 ft otherwise.

In controlled airspace obtain and comply with clearance and the reporting/communication rules. Outside controlled airspace follow the applicable cruising-level table, communication and reporting requirements for the designated airspace. IFR in Class G does not automatically receive ATC separation from all traffic.

Cancel deliberately

The PIC initiates a change from IFR to VFR and must be able to continue in uninterrupted VMC for the relevant period with the intention of doing so. ATS does not invite or force cancellation simply because weather improves. Notify the appropriate unit with the specific cancellation and flight-plan changes.

A visual approach is still an IFR approach under an IFR clearance. The clearance to fly visually for part of the approach does not by itself cancel IFR, alter the aircraft’s eligibility or remove the applicable separation service.

Semicircular cruising-level example

Under the ordinary ICAO table, magnetic tracks 000–179 degrees use odd IFR levels such as FL050/070/090, with VFR levels 500 ft higher such as FL055/075/095; tracks 180–359 use even IFR levels such as FL060/080/100 and VFR FL065/085/105. Above the lower-level table the RVSM/non-RVSM structure changes the available sequence. Apply ATC clearances, the published route direction and State exceptions instead of selecting a level solely from this example. Heading corrected for wind is not the magnetic track that determines the table.

Can you apply the rules?

Four original questions. Choose from the facts, then review the explanation.