Required Instruments and Warning Systems - ATPL 070 — Operational Procedures

This lesson is a shopping list with legal force: what the flight deck must contain before a commercial aeroplane may fly. Two numbers organise almost everything in it, a take-off mass of 5,700 kg and a maximum operational passenger seating configuration, MOPSC, of nine, with certificate-of-airworthiness dates supplying the fine print. How each instrument works belongs to the instrumentation course; what must be bolted in, and to whom, belongs here.

Approved, unless the list says otherwise

Instruments and equipment required by the subpart are approved under the airworthiness rules, with a short list of exceptions the exam asks by name: spare fuses, independent portable lights, an accurate time piece, a chart holder, first-aid kits, the emergency medical kit, megaphones, survival and signalling equipment, sea anchors and mooring equipment, and child restraint devices. Equipment that is carried without being required lives under two conditions: its information is not used by the crew to satisfy any requirement, and it must not affect airworthiness even when it fails. Four placement rules finish the frame: equipment used by one crew member is readily operable from that station, equipment that more than one crew member must operate is readily operable from each of those stations, instruments are visible with minimum deviation from the pilot's normal line of vision, and all required emergency equipment is easily accessible for immediate use.

When something on the list is broken, the minimum-equipment rule the commander lesson met takes over: a flight is not commenced with required instruments, equipment or functions inoperative or missing, unless the aeroplane is operated under the operator's MEL, or the operator holds the competent authority's approval to operate within the constraints of the master MEL. The MEL system itself gets a later module.

Fuses and a clear windshield

Aeroplanes carry spare electrical fuses of the ratings required for complete circuit protection, for those fuses that may be replaced in flight, and the count is the higher of 10 per cent of the number of fuses of each rating or three per rating. The guidance draws the boundary: a spare fuse means a replaceable fuse in the flight crew compartment, not the automatic circuit breakers or the breakers in the electrical bays. And aeroplanes with an MCTOM above 5,700 kg carry, at each pilot station, a means of keeping a portion of the windshield clear in precipitation: windshield wipers or an equivalent.

The day VFR panel

Under VFR by day, the pilot's station must offer a means of measuring and displaying ten things, plus a warning that the instruments' power supply is failing:

Magnetic heading — a magnetic compass or equivalent.
Time — in hours, minutes and seconds.
Barometric altitude — sensitive, calibrated in feet, with a sub-scale in hectopascals adjustable to any pressure likely in flight.
Indicated airspeed — calibrated in knots.
Vertical speed.
Turn and slip.
Attitude.
Heading.
Outside air temperature — in degrees Celsius, or convertible to it.
Mach number — whenever speed limitations are expressed in Mach.

Where the operation needs two pilots, the second gets separate displays of six of them: barometric altitude, indicated airspeed, vertical speed, turn and slip, attitude and heading. Pitot protection is threshold-gated: a means of preventing airspeed-system malfunction from condensation or icing, a heated pitot tube or equivalent, is required above 5,700 kg or nine passenger seats, and on every aeroplane certificated on or after 1 April 1999. One relaxation exists for local flights: taking off and landing at the same aerodrome, within 50 NM and 60 minutes, the turn-and-slip and stabilised-heading requirements may be met by a turn and slip indicator, a turn coordinator, or an attitude indicator with a slip indicator. The lights complete the day fit: an anti-collision light system, powered lighting for essential instruments and for every passenger compartment, and an independent portable light at each required crew member's station; night operations add navigation and position lights, two landing lights or a single one with two separately energised filaments, and seaplanes conform to the collision regulations at sea.

IFR and the night

IFR, and VFR at night, keep the same measuring list with two upgrades and a stack of system requirements. The altimetry doubles: two means of measuring and displaying barometric altitude, and neither a three-pointer nor a drum-pointer altimeter satisfies the requirement, except on an unpressurised aeroplane operating below 10,000 ft. The turn-and-slip means may reduce to a slip indicator alone where a standby attitude means is fitted. Pitot heating becomes universal for IFR, and its failure annunciation is required for aeroplanes certificated on or after 1 April 1998, and for older ones only when both above 5,700 kg and above nine seats. Static sources split by size: two independent static pressure systems, except propeller-driven aeroplanes at or below 5,700 kg, which may pair one system with an alternate source. A chart holder sits in an easily readable position, illuminable for night, and an electronic flight bag displaying a pre-composed chart is an acceptable way to provide it.

The centrepiece above 5,700 kg or nine seats is the standby attitude indicator, usable from either pilot's station, and its specification is a list the exam quotes: powered continuously in normal operation and, after total failure of the normal generating system, from an independent source; reliable for at least 30 minutes after that total failure, other emergency loads considered; independent of every other attitude means; automatically operative after total generating failure; appropriately illuminated in all phases; with clear evidence to the crew when it runs on emergency power, and an indication when a dedicated supply is in use.

One pilot under IFR

The single-pilot IFR addition is one sentence of rule: an autopilot with at least altitude hold and heading mode. The workload argument behind it is obvious; the exam's favourite move is to swap the two required modes for others, so hold the pair exactly.

The altitude alerter

An altitude alerting system is required for turbine-propeller aeroplanes above 5,700 kg or nine seats, and for every turbojet, whatever its size. It must be able to alert the crew when approaching a preselected altitude, and to alert them, by at least an aural signal, when deviating from one. A narrow grandfather clause spares small nine-plus-seaters certificated before 1 April 1972 and registered in a member state on 1 April 1995.

Terrain and traffic

The terrain awareness warning system splits by engine and class. Class A TAWS is for turbine-powered aeroplanes above 5,700 kg or nine seats. Class B covers reciprocating-engine aeroplanes above the same thresholds, and reaches down to small turbines: certificated after 1 January 2019, at or below 5,700 kg, with six to nine seats. What the classes contain, the modes and their voices, is the instrumentation course's material; one carriage-flavoured AMC note is worth keeping: the Class A glide-slope-deviation warning applies to angular vertical guidance, an ILS, MLS, LPV or GLS, not to barometric VNAV.

Traffic protection draws its line differently, and the difference is the exam's favourite trap in this subpart: ACAS II is required for turbine-powered aeroplanes above 5,700 kg or with an MOPSC above 19. Terrain watches over more than nine seats; traffic waits for more than nineteen.

Seeing the weather

Airborne weather detecting equipment is conditional on the weather itself: it is required when operating at night or in IMC in areas where thunderstorms or other potentially hazardous, detectable weather may be expected along the route, and it catches three groups: pressurised aeroplanes, non-pressurised aeroplanes above 5,700 kg, and non-pressurised aeroplanes with more than nine seats. The equipment should be an airborne weather radar, with one carve-out: propeller-driven pressurised aeroplanes at or below 5,700 kg with nine seats or fewer may carry other equipment capable of the same detection.

The voice in the box

The cockpit voice recorder is compulsory for aeroplanes above 5,700 kg, and for multi-engined turbine aeroplanes at or below that mass with more than nine seats certificated on or after 1 January 1990. Its memory is time-based: at least the preceding 25 hours for aeroplanes above 27,000 kg certificated on or after 1 January 2022, and at least the preceding 2 hours in all other cases, recorded on something other than magnetic tape or wire. What it captures, against a timescale: radio transmissions from and to the flight deck, crew voices on the interphone and public address, the aural environment of the flight crew compartment including, without interruption for post-April-1998 aeroplanes, each boom and mask microphone in use, and the audio idents of navigation and approach aids.

Operationally the recorder brackets the flight: it records from before the aeroplane moves under its own power until it can no longer do so, automatically for aeroplanes certificated on or after 1 April 1998, and, power permitting, from the cockpit checks before engine start to the checks after shutdown, an early start owed only by the post-April-1998 heavies and by every aeroplane of the small multi-turbine carriage group. A non-deployable recorder carries an underwater locating device transmitting for at least 90 days; a deployable one carries an automatic ELT instead. And the newest heavies, above 27,000 kg and certificated on or after 5 September 2022, add an alternate power source that picks up the CVR and the cockpit area microphone automatically when all other power fails, good for about 10 minutes.

The numbers in the box

The flight data recorder, digital and readily retrievable, is compulsory for three groups: aeroplanes above 5,700 kg certificated on or after 1 June 1990; turbine aeroplanes above 5,700 kg certificated before that date; and multi-engined turbine aeroplanes at or below 5,700 kg with more than nine seats certificated on or after 1 April 1998. What it must hold scales with the aeroplane's vintage: the oldest group records at least time, altitude, airspeed, normal acceleration and heading, while the rest record the parameters needed to determine the flight path, speed, attitude, engine power and configuration, with operation added for the newest and heaviest. Retention is at least the preceding 25 hours, trimmed to 10 hours only for the small pre-2016 nine-plus-seat group. Two operating rules mirror the CVR: data comes from sources allowing accurate correlation with what the crew saw, recording brackets the aeroplane's ability to move under its own power, automatic from the same 1 April 1998 line, and the same 90-day underwater locator or deployable-ELT rule applies.