Aeroplane Equipment and Instruments — Page 82, Lesson 128

I want to walk you through the equipment requirements for operating an aeroplane under different flight rules. This is a foundational list that every professional pilot must know cold, because it tells you exactly what instruments must be serviceable before you can legally depart. Let's start with the big picture. When an aircraft is operated under VFR — Visual Flight Rules — the assumption is that you can navigate visually, by looking out the window. Flight under IFR — Instrument Flight Rules — is the opposite: it requires the use of radio navigation aids and more sophisticated instrumentation, because you're flying without visual reference to the ground. Now, for all aeroplanes operated under VFR during the day, the regulations prescribe a specific set of mandatory equipment. Let me go through each item in order. First, item (a): a magnetic compass. This is your basic heading reference, independent of any electrical system. Item (b): an accurate timepiece showing the time in hours, minutes, and seconds. You need this for navigation timing, fuel management, and position reporting. Item (c): a sensitive pressure altimeter calibrated in feet, with a subscale setting calibrated in hectopascals or millibars. That subscale must be adjustable for any barometric pressure likely to be set during flight. So you can set QNH or QFE as needed, and the instrument reads altitude in feet. Item (d): an airspeed indicator calibrated in knots. Not miles per hour — knots. Item (e): a vertical speed indicator. That tells you your rate of climb or descent, usually in feet per minute. Item (f): a turn and slip indicator, or a turn coordinator incorporating a slip indicator. The turn and slip indicator shows rate of turn and coordination; the turn coordinator does the same job but with a different display principle, and it must include a slip indicator — that's the inclinometer ball. Item (g): an attitude indicator. This gives you a pitch and roll reference — your artificial horizon. Item (h): a stabilized direction indicator. That's your directional gyro or heading indicator, which is gyroscopically stabilised so it doesn't precess like a magnetic compass during turns. Item (i): a means of indicating in the flight crew compartment the outside air temperature, calibrated in degrees Celsius. That's your OAT gauge, critical for anti-icing decisions and performance calculations. Now, there's an important relief provision in subparagraph (j). For flights that do not exceed 60 minutes duration, which take off and land at the same aerodrome, and which remain within 50 nautical miles of that aerodrome, you can reduce the instrument requirement. Specifically, the instruments prescribed in subparagraphs (f), (g), and (h) — that's the turn and slip or turn coordinator, the attitude indicator, and the stabilised direction indicator — plus subparagraphs (k)4, (k)5, and (k)6 which we'll get to in a moment, may all be replaced by either a turn and slip indicator, or a turn coordinator incorporating a slip indicator, or both an attitude indicator and a slip indicator. So for a short local flight, you don't need the full six-pack; you can get by with just a turn instrument and a slip indicator, or just an attitude indicator plus a slip indicator. Next, subparagraph (k) addresses the situation whenever two pilots are required. In that case, the second pilot's station must have separate instruments. Let me list those: 1. A sensitive pressure altimeter calibrated in feet with a subscale setting in hectopascals or millibars, adjustable for any barometric pressure likely to be set during flight — identical to the captain's. 2. An airspeed indicator calibrated in knots. 3. A vertical speed indicator. 4. A turn and slip indicator, or a turn coordinator incorporating a slip indicator. 5. An attitude indicator. 6. A stabilised direction indicator. So the second pilot gets essentially the same basic flight instruments as the captain, but note that the magnetic compass and the outside air temperature indication are not duplicated for the second pilot — those are only required at one station. Finally, subparagraph (l) deals with pitot heat requirements. Each airspeed indicating system must be equipped with a heated pitot tube or equivalent means for preventing malfunction due to either condensation or icing. This applies to aeroplanes with a maximum certificated take-off mass in excess of 5700 kilograms, or having a maximum approved passenger seating configuration of more than 9. So if your aeroplane is heavier than 5700 kg MCTOM, or it seats more than 9 passengers, you must have pitot heat on every airspeed system. That's a critical anti-ice requirement. So to summarise: for a standard day VFR flight, you need the full list from (a) through (i). For a short local flight under 60 minutes and within 50 NM of the same aerodrome, you can reduce the attitude, heading, and turn instruments. And if you're operating with a required second pilot, that station gets its own set of six basic flight instruments. Plus, heavier or higher-capacity aeroplanes need heated pitot systems.