The Air Navigation Order 1989

3.  The scales of radio and radio navigation equipment indicated in the foregoing Table shall be as follows:

• Scale A

  Radio equipment capable of maintaining direct two-way communication with the appropriate aeronautical radio stations.

• Scale B

  Radio navigation equipment capable of enabling the aircraft to be navigated on the intended route including such equipment as may be prescribed.

• Scale C

  Radio equipment capable of receiving from the appropriate aeronautical radio stations meteorological broadcasts relevant to the intended flight.

• Scale D

  Radio navigation equipment capable of receiving signals from one or more aeronautical radio stations on the surface to enable the aircraft to be guided to a point from which a visual landing can be made at the aerodrome at which the aircraft is to land.

• Scale E

  Secondary surveillance radar equipment.

• Scale F

  Radio and radio navigation equipment capable of enabling the aircraft to be navigated along the intended route including either:

  (a)

  (i)

  automatic direction finding equipment;

  (ii)

  distance measuring equipment; and

  (iii)

  VHF omni-range equipment: or

  (b)

  equipment, including the Decca Flight Log, which will enable the aircraft to be navigated by means of signals received from radio navigation land stations forming part of the Decca radio navigation system and which provides the pilot with a visual indication of the aircraft’s position relative to the intended route.

• Scale G

  Radio navigation equipment capable of enabling the aircraft to make an approach to landing using the Instrument Landing System.

• Scale H

  Radio navigation equipment capable of enabling the aircraft to be navigated on the intended route including:

  (a)

  automatic direction finding equipment;

  (b)

  distance measuring equipment;

  (c)

  duplicated VHF omni-range equipment; and

  (d)

  a 75 MHz marker beacon receiver;

  Except that:

  • an aircraft may fly notwithstanding that it does not carry the equipment specified in this Scale if it carries alternative radio navigation equipment or navigational equipment approved by the Authority in writing in accordance with the provisions of article 13(7) of this Order;

  • where not more than one item of equipment specified in this Scale is unserviceable when the aircraft is about to begin a flight, the aircraft may nevertheless take off on that flight if:

    (i)

    it is not reasonably practicable for the repair or replacement of that item to be carried out before the beginning of the flight;

    (ii)

    the aircraft has not made more than one flight since the item was last serviceable; and

    (iii)

    the commander of the aircraft has satisfied himself that, taking into account the latest information available as to the route and aerodrome to be used (including any planned diversion) and the weather conditions likely to be encountered, the flight can be made safely and in accordance with any relevant requirements of the appropriate air traffic control unit.