Night IFR
Certain LAA types can be cleared for flight at night and/or under IMC (instrument meteorlogical conditions) - commonly referred to as 'Night/IFR' for convenience. The special Night/IFR requirements and process are detailed in technical leaflets TL 2.27 and 2.28, linked below, which are additional to the standard requirements applicable to any LAA aircraft.
The special requirements involve the aircraft being of a type that demonstrates flight handling broadly in accordance with CS-23 subpart B (some types, including the RV-6 and RV-7, have a restricted aft cg limit to meet the pitch stability requirements), and each individual example must have a special IFR flight test to confirm it matches the first one tested. For a night clearance, the aircraft must also undergo a night test to check its lighting and general suitability for night flight.
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The aircraft must have accumulated enough flying hours in VFR to prove its reliability, and it must have an engine of a type accepted as being likely to be as reliable as a certified engine (for example we accept ‘clone’ Lycomings even though not certified). The propeller must be rain-proof, i.e. have hardened leading edges, and the aircraft must have an effective carb ice prevention system. The aircraft’s panel must have at least two independent attitude indicators, with either separate power sources or back-up internal power. If two EFIS are used to provide attitude information, with no other attitude instrument, then the two EFIS must be of different manufacturers so as to avoid the risk of simultaneous failures. There must be pitot heat, an alternative static and an OAT gauge. If the essential systems are relying on electrical power, the electrics must be designed to avoid being vulnerable to any single component failure, and if there is a single alternator there must be enough battery capacity to keep the essential systems running for an adequate time (at least 30 mins) before the battery goes flat. If two radios are fitted, they must not be both vulnerable to failure if any single component fails (e.g. must not be both fed through a single avionics master switch with no back-up power available). LAA does not specify what navigation or radio equipment is fitted, but as with a certified aircraft, the equipment fit determines what type of airspace can be used. An autopilot is not required, but certainly helps reduce pilot workload in sustained instrument flight. Non-certified equipment, including EFIS and autopilots, alternators, etc, are permitted, subject to the usual LAA checks.
The aircraft has to be inspected initially and annually by an inspector with a special ‘night/IFR’ endorsement on their LAA inspector approval, and the aircraft is checked to have been built to an appropriate level of quality for a night/IFR aircraft. For example, quality of its instrument wiring, electrical power supply wiring, etc, are checked which are much more critical than in an aircraft only flying day VFR. The ASI and altimeter must be regularly calibrated, the battery must have a regular capacity check and the radios checked regularly by a qualified radio engineer. The aircraft must have an accepted pilot’s operating handbook and an acceptable maintenance schedule, and be maintained to that schedule.
The application process involves not only a night/IFR inspector but also a night/IFR assessor who is one of a small band of LAA volunteers qualified to assess the design aspects of the aircraft’s systems and who compiles a technical report about the aircraft and if he is happy with it, includes a recommendation to remove the day-VFR only restriction. The report includes details of the aircraft’s systems, the special flight test reports, inspection reports, maintenance schedule and POH, a photo of the instrument panel and an electrical load analysis. This report is sent to LAA Engineering who checks through it and all being well, issues the aircraft new paperwork with the day and/or VFR restriction removed and replaced by limitations allowing IFR and/or night flight.
All LAA night/IFR aircraft are restricted to not fly in the vicinity of thunderstorms and, for IFR cleared aircraft, take-off and landing in visibility less than 1500m is prohibited. The aircraft may not be operated in IMC below 500 ft agl for a precision approach, or 600 ft for a non-precision approach, or approach system limits, whichever is the greater.
The pilot qualification for flying an LAA night/IFR aircraft at night or in IFR is the same as for flying a certified light aircraft at night or IFR.
Aircraft types that have been successfully cleared for night/IFR flight include the RV-6, -7, -8, -9 and -10 (nosewheel and tailwheel variants – some with cg range restrictions), Europa and Cozy. Several of the modern lightweight 600 kg types have failed to comply due to low stability margins making them OK for day VFR flight but not suitable instrument platforms for night or IFR. Whilst a very few Rotax powered aircraft have been be to be cleared, most of the thirty or so LAA aircraft that have successfully transitioned are powered by Lycoming or Lycoming-clone engines.