The Air Navigation Order 2009

4.  The scales of radio communication and radio navigation equipment indicated in the Table at paragraph 3 are as follows—

• Scale A

  Radio communication equipment capable of maintaining direct two-way communication with the appropriate air traffic control units on the intended route using the frequencies notified or otherwise designated by the competent authority for that purpose.

• 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 communication 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 E2(1)

  Secondary surveillance radar equipment which includes a pressure altitude reporting transponder capable of operating in Mode A and Mode C and has the capability and functionality prescribed for Mode S Elementary Surveillance and is capable of being operated in accordance with such instructions as may be given to the aircraft by the air traffic control unit.

• Scale E3

  Secondary surveillance radar equipment which includes a pressure altitude reporting transponder capable of operating in Mode A and Mode C and has the capability and functionality prescribed for Mode S Enhanced Surveillance and is capable of being operated in accordance with such instructions as may be given to the aircraft by the air traffic control unit.

• Scale EE

  The aircraft must, in the circumstances specified in paragraph 2.1.5.3 of Volume IV (Fourth Edition July 2007) of Annex 10 to the Chicago Convention, comply with the requirements for antenna diversity set out in that paragraph.

• Scale F

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

  (a)

  automatic direction finding equipment;

  (b)

  distance measuring equipment; and

  (c)

  VHF omni-range equipment.

• Scale G

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

• Scale H

  (1)

  Subject to paragraphs (2) and (3), 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.

  (2)

  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 in accordance with article 37(9).

  (3)

  Where only 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—

  (a)

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

  (b)

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

  (c)

  the commander of the aircraft is satisfied that the flight can be made safely and in accordance with any relevant requirements of the appropriate air traffic control unit, 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.

• Scale J

  An airborne collision avoidance system.

(1)

Scale E1 was formerly defined as secondary surveillance radar equipment which includes a pressure altitude reporting transponder capable of operating in Mode A and Mode C and capable of being operated in accordance with such instructions as may be given to the aircraft by the air traffic control unit. There is no longer any requirement to carry Scale E1 but some aircraft may continue to carry it under a transitional exemption issued by the CAA.