Definitions - a Discussion
There are two main types of microlight / ultralight; the 3-axis (or fixed wing) type which are similar in appearance to a conventional aeroplane and the flexwing type which consists of a delta or parachute type wing similar to that of a hang glider or paraglider with a 'tricycle undercarriage' unit suspended underneath it. The latter is also sometimes referred to as a Paramotor or Powered Paraglider (PPG). This type of microlight is controlled either by weight shift or by means of a paraglider control system. Most unpowered microlights are foot paragliders and hang gliders anf are foot launched. Now that there is no longer necessarily any obvious visually-detectable difference between 'conventional' small / light aircraft and 'very small' Microlight or Ultralight 3-axis aircraft, the term 'small manned aircraft' is often used whilst having no universally-accepted definition. However, this term is not analogous to the similar term Small Unmanned Aircraft (SUA) where regulatory agencies have begun to apply weight definitions to the term.
There is no universally-accepted definition of a Microlight / Ultralight aircraft either, but the following definition found in ICAO documentation remains the most generally relevant in respect of the operation of such aircraft and the concessions against normal aircraft regulatory requirements which are normally applied.
"An aircraft having a MTOM not exceeding 454 kg /1000 lbs which is not usually used for public transport purposes, has no more than two seats, has a Vs not exceeding 35 KCAS and has a maximum take-off mass of no more than:
- 300 kg for a landplane, single seater; or
- 330 kg for an amphibian or floatplane, single seater; or
- 495 kg for an amphibian or floatplane, two-seater, provided that a microlight capable of operating as both a floatplane and a landplane falls below both MTOM limits, as appropriate.
- 450 kg for a landplane, two-seater.
Note that foot-launched (flexwing) microlight aircraft, which in reality can appear at a distance to be very similar to the same type of microlights which has a fixed tricycle undercarriage, are excluded from this definition.
This definition corresponds to the ICAO-directed use of the following generic microlight aeroplane type codes:
- Microlight aircraft - ULAC
- Microlight autogyro - GYRO
- Microlight helicopter - UHEL
Experience to date with microlight helicopters and autogyros has been limited and their overall safety record has been comparatively poor.
Various adaptations of this ICAO generic definition are in use in different States. For example:
In the UK - the CAA defines a (powered) microlight aeroplane as "one designed to carry not more than two persons which has either a stalling speed at the Maximum Total Weight Authorised (MTWA) which does not exceed 35 KCAS or a wing loading at the MTWA not exceeding 25 kg per square metre". The various MTWA which apply are as follows:
- 300 kg for a single seat landplane.
- 390 kg for an amateur-built single seat landplane for which a UK Permit to Fly or Certificate of Airworthiness was in force prior to 1 January 2003
- 450 kg for a two seat landplane
- 330 kg for a single seat amphibian or floatplane
- 495 kg for a two seat amphibian or floatplane
- 315kg for a single seat landplane equipped with an airframe mounted total recovery parachute system
- 472.5kg for a two-seat landplane equipped with an airframe mounted total recovery parachute system
Note that this definition does not apply to rotorcraft or gyroplanes.
In the USA, the Federal Aviation Administration (FAA) defines an Ultralight Vehicle as one which can be operated within the terms of 14 CFR Part 103 and as detailed in 103-7 'The Ultralight Vehicle' . The requirements are:
- It is used or intended to be used for manned operation in the air by a single occupant
- It is used or intended to be used for recreation or sport purposes only
- It does not have any U.S. or foreign airworthiness certificate
- If powered, it weighs less than 254lbs empty weight excluding floats and safety devices which are intended for deployment in a potentially catastrophic situation, has a fuel capacity not exceeding 5 US gallons, is not capable of more a speed of more than 55 KCAS at full power in level flight and has a power-off stall speed which does not exceed 24 KCAS
- If unpowered, it weighs less than 155lbs empty weight, excluding floats and safety devices which are intended for deployment in a potentially catastrophic situation
In most jurisdictions where regulations specific to ultralight / microlight operation exist, there are restrictions on how, when and / or where they may be operated.
It is usual for there to be a requirement that they shall not be operated in a way that creates a hazard to other people or property or aircraft and that nobody may allow an object to be dropped from such an aircraft either under any circumstances or where such an action would create a hazard to other people or property.
It is also usual for there to be some form of restriction in operations over the congested area of a city, town, or settlement, or over any open air assembly of a significant number of people but the exact requirements and definitions in thus respect vary widely.
Many jurisdictions restrict all ultralight / microlight operations to those which are "operated by visual reference with the surface" and these may vary according to height above the surface in respect of the minimum in flight visibility and distance from cloud. Many also restrict access to some classes of controlled airspace and to restricted or prohibited airspace either conditionally (based, for example on air traffic control awareness or permission and /or prevailing in-flight weather conditions) or completely and may require ultralight / microlight pilots to be aware of relevant NOTAMs detailing temporary airspace access restrictions.
The Federal Aviation Administration (FAA) requires that ultralight vehicles must only be operated between the hours of sunrise and sunset unless they are equipped with an operating anti-collision light visible for at least 3 sm and remain outside controlled airspace, in which case they may additionally be operated during civil twilight - the period of 30 minutes before official sunrise and after official sunset which qualifies as 'day' flying for civil pilots who are required to record their flying hours.
Right-of-way of ultralights /microlights relative to other types of aircraft may sometimes differ from the basic specification given in ICAO Annex 2, in particular in relation to converging aircraft. In this case, Annex 2 requires that "power-driven heavier-than-air aircraft shall give way to airships, gliders and balloons" but, for example, the FAA requires that "ultralight vehicles must give way to all other aircraft and that powered ultralights must give way to unpowered ultralights". The practicality of a jet transport aircraft giving way to a microlight aircraft has been questioned as the number of AIRPROX events involving such conflicts has increased as the amount of microlight flying has increased, see for example an event near Southend, United Kingdom in 2013.
Certification and Registration
Regulatory Requirements for both certification and registration of microlight / ultralight aircraft are usually less stringent than for larger aircraft but the detail varies. In the USA, the FAA does not require 'ultralight vehicles' or their component parts and equipment to meet any airworthiness certification standards or to have Certificates of Airworthiness and they are not required to be registered or to carry identification markings of any type.
In other jurisdictions, for example the UK, registration of ultralight / microlight aircraft is required and whilst they are not subject to either direct airworthiness oversight by the CAA, their operators are required to be able to demonstrate that the aircraft is fundamentally safe when in good condition. Operator assurance of this 'good condition' through regular and thorough inspection thus becomes very important since the type of comprehensive safe-life, and / or damage-tolerance investigation that is usually required for aircraft which are required to hold a Certificate of Airworthiness aircraft does not apply.
The extent to which microlight pilots need to hold a licence varies according to regulatory jurisdiction. In the USA, pilots of ultralight vehicles are not required to hold any pilot licence or medical fitness certification or to otherwise satisfy any aeronautical knowledge, age, or experience requirements.
In the UK, an appropriate version of a National PPL (NPPL) is required to fly a microlight aeroplane. This is issued by the CAA after successful completion of specified ground and flight training, the passing of a general skills test and the acquisition of corresponding medical certification is required. Pilot training and testing is delegated to the British Microlight Aircraft Association (BMAA). Under UK legislation, some Self Launching Motor Gliders (SLMG) also fall within the definition of a single seat microlight aeroplane. In the UK, there is no requirement for mandatory pilot training or pilot licensing and although there is, as in other countries, a body which oversees Hang Gliding and Paragliding, membership and the corresponding training available is not mandatory.