Communication and Navigation Equipment - ATPL 070 — Operational Procedures

The module closes with the equipment that lets the aeroplane talk and find its way. The pattern of this subpart is delegation: the operating rules rarely name a box, instead demanding whatever the applicable airspace requirements prescribe, and then adding redundancy, an emergency channel and honest data on top. How a VOR or a transponder works is the instrumentation course's affair, and which code to squawk when is Air Law's; here the question is what must be installed and why.

The general fit

Aeroplanes carry the radio communication equipment the airspace requires, and under IFR, or VFR where the route cannot be navigated by visual landmarks, communication, navigation and surveillance equipment to the same standard. Above that baseline sit four general demands. Navigation equipment is sized for failure: after the loss of one item at any stage of flight, what remains must still allow safe navigation in accordance with the flight plan, and the installation should ensure that no single unit's failure takes another required unit with it. Flights intending to land in IMC carry equipment providing guidance to a point from which a visual landing can be made, at every intended IMC destination and every designated alternate. PBN operations need the airworthiness certification for the navigation specification flown. And the people are wired in too: a headset with boom or throat microphone for each flight crew member at the station, a transmit button on the manual pitch and roll control for each required pilot under IFR or at night, and, whenever more than one flight crew member operates the aeroplane, a flight crew interphone system with headsets and microphones, which should not be of a handheld type.

The emergency frequency

One frequency is named in the rule itself: the radio communication equipment must provide for communication on 121.5 MHz, the aeronautical emergency frequency. The reasons live in the rest of the course: it is the channel a station in distress or urgency can always reach, the channel an intercepting aircraft will call as Air Law taught, and the channel the previous lesson's ELTs transmit on alongside 406 MHz. A frequency everyone can hear only works if everyone can tune it, so the fit is unconditional.

Choosing what you hear

Under IFR an audio selector panel is required, operable from each required flight crew member station. With two communication systems, several navigation receivers and an interphone all feeding the same two ears, the panel that routes and silences them stops being convenience and becomes equipment.

VFR by landmarks

For VFR over routes navigated by reference to visual landmarks, the radio fit is a three-line capability list, judged under normal radio propagation conditions:

communicate with appropriate ground stations;
communicate with ATC from any point in the controlled airspace the flight intends to enter; and
receive meteorological information.

IFR: two of everything that matters

The IFR communication rule is counted: at least two independent radio communication systems, able under normal conditions to raise an appropriate ground station from any point on the route, diversions included, each with its own antenna installation unless rigidly supported non-wire antennae make sharing acceptable. One carve-out looks ahead to the North Atlantic module: short-haul operations in NAT HLA airspace that do not cross the Atlantic may carry a single long-range communication system, an HF set or another permitted system, where alternative procedures are published for the airspace.

The navigation fit is described by the acceptable means of compliance as a workable minimum: a VOR receiver, an ADF and a DME, with an ILS or MLS receiver and a marker receiver where the approach demands them, area navigation equipment where the route does, and a second DME, VOR or ADF on any route leg where navigation leans on that signal alone. The ADF carries its own modern footnote: it need not be installed at all when no phase of the planned flight requires it, and an operator flying IFR without ADF should hold to a clean set of conditions: no route segment relying solely on ADF, no ADF or NDB procedures flown, the MEL amended, the operations manual free of NDB-based procedures for the type, planning and dispatch consistent with all of it, and the training syllabus adjusted. The VHF communication, ILS localiser and VOR receivers that remain should meet the FM immunity standards, so broadcast stations cannot bleed into the localiser.

Flying the corridor

The Flight Planning course fixed the RVSM geography, FL 290 to FL 410 with 1,000 ft between levels, and the second module filed the approval among the operator's tickets. The equipment side is a four-item set, and the exam wants it complete:

two independent altitude measurement systems, each built around a cross-coupled static system with measuring, displaying and digitising equipment among its components;
an altitude alerting system;
an automatic altitude control system; and
an SSR transponder with altitude reporting that can be connected to the altitude measurement system in use for altitude control.

Talking to the cabin

The crew member interphone system arrives at an MCTOM above 15,000 kg or an MOPSC above 19, one of the rare places this subpart uses a mass line other than 5,700 kg, with a grandfather clause for aeroplanes certificated before April 1965 and long registered. Its specification is a communications map: independent of the public address system except for shared handsets, headsets, microphones, selector switches and signalling devices, readily accessible at required cabin crew stations near the floor-level exits and at each required flight crew station, fitted with aural or visual alerting and a means of telling a normal call from an emergency call, by light colours, ring codes or another operations-manual signal, and providing two-way speech between the flight deck and each passenger compartment, each galley off the passenger deck and each remote crew station, and between the ground personnel and at least two flight crew members, through a connection point sited, where practicable, so the ground crew cannot be seen from inside.

The public address system keys on seats alone: required above an MOPSC of 19. It should be independent of the interphones, immediately usable from the flight crew stations, offer a microphone at each floor-level passenger exit with an adjacent cabin crew seat, one microphone serving neighbouring exits where seated crew can talk to each other unassisted, be operable by a seated cabin crew member within 10 seconds, and be audible at every passenger seat, lavatory, galley, crew seat and remote work station.

Squawking

The transponder rule is one sentence with two halves: a pressure-altitude-reporting SSR transponder, plus any other SSR transponder capability the route being flown requires, the whole operating under the Single European Sky legislation in European airspace and ICAO Annex 10 elsewhere. What to squawk on it, and when 121.5 and the emergency codes meet, stayed with Air Law.

The data behind the map

The navigation boxes are only as good as their databases, so the rule regulates the data. Aeronautical databases used on certified aircraft applications meet data quality requirements adequate to their intended use, and the operator ensures the timely distribution and insertion of current, unaltered databases to every aircraft that needs them; the guidance has that distribution follow the database's validity period, or an operations-manual procedure where none is defined. When the database feeds a primary means of navigation, its provider should be a certified Type 2 DAT provider. And when the data is wrong, the duty is threefold: report erroneous, inconsistent or missing data that could reasonably hazard a flight to the database provider, inform the flight crews and personnel concerned, and ensure the affected data is not used.