Meet the six-pack

Walk up to any traditional light aeroplane in the UK and you’ll see a panel of round dials. The core set is often called the six-pack. In a typical trainer, they’re arranged in a standard T or two rows. The top row usually has the airspeed indicator, attitude indicator and altimeter. Below them sit the turn coordinator, heading indicator and vertical speed indicator. Some aircraft add engine gauges, a compass and a GPS, but these six are your foundation.

• Airspeed indicator (ASI) — shows indicated airspeed in knots. It compares ram air pressure from the pitot tube with static pressure.
• Attitude indicator (AI) — shows pitch and bank relative to the horizon. Also called the artificial horizon.
• Altimeter — shows your height above a chosen pressure datum, usually in feet.
• Turn coordinator — shows rate of turn and whether you’re coordinated. The inclinometer ball sits below.
• Heading indicator (HI) — shows your magnetic heading, but must be set periodically against the magnetic compass.
• Vertical speed indicator (VSI) — shows rate of climb or descent in feet per minute.

Pitot and static: the pressure instruments

Three of the six rely on pressure. The ASI needs both pitot and static pressure. The altimeter and VSI use static pressure only. That matters when things go wrong. If the pitot tube blocks, the ASI can behave like an altimeter — climbing produces a higher reading, descending a lower one. If the static port blocks, all three pressure instruments lie to you. Pitot heat is there for a reason, especially in the UK’s damp, cold air at altitude.

The ASI is your primary speed guide. In a light aeroplane, you’ll learn target speeds for climb, cruise, approach and stall. The altimeter tells you how high you are above mean sea level when set to QNH. The VSI is a trend instrument: it lags slightly, so use it to confirm what the altimeter and attitude indicator are already telling you.

Gyroscopic instruments: attitude, heading and turn

The attitude indicator, heading indicator and turn coordinator are gyroscopic. In older trainers they’re driven by engine vacuum or pressure; in newer panels they may be electric or digital. Each has quirks.

• Attitude indicator: the miniature aircraft and horizon bar show pitch and bank. It’s your primary pitch instrument. It may tumble after aggressive manoeuvres, so smooth handling pays.
• Heading indicator: it precesses over time. Set it to the magnetic compass before take-off and check it in cruise. The compass itself has turning and acceleration errors, so use it straight and level.
• Turn coordinator: a standard-rate turn is 3° per second, a full 360° in two minutes. The ball tells you if you’re slipping or skidding. Step on the ball — that is, add rudder towards the ball — to coordinate.

Colour arcs and markings

The ASI is the most colourful dial. Learn the arcs before you fly.

• White arc: flap operating range. The lower limit is the stall speed with flaps extended (VS0), the upper limit is maximum flap extended speed (VFE).
• Green arc: normal operating range. The lower limit is stall speed clean (VS1), the upper limit is maximum structural cruising speed (VNO).
• Yellow arc: caution range. Fly here only in smooth air and with care.
• Red line: never-exceed speed (VNE). Treat it as a hard limit.

The altimeter has a subscale window in hectopascals (hPa). The VSI reads zero when level. The heading indicator has a small adjustment knob. The turn coordinator has a miniature aeroplane and a ball.

Altimeter settings in UK airspace

In the UK, you’ll use QNH and QFE. QNH is the pressure setting that makes the altimeter read altitude above mean sea level. QFE makes it read height above a specific aerodrome. Most training flights use QNH. When you’re below the transition altitude — often 3,000 ft, but check the chart because it can be higher — set your altimeter to the aerodrome QNH from the ATIS or tower.

Above the transition altitude, set the standard pressure setting of 1013.25 hPa and fly flight levels. On the way down, set QNH at the transition level. A 1 hPa error is about 27 feet, so a 4 hPa mistake is over 100 feet. In cloudy UK weather, that matters. Get into the habit of confirming the subscale during your approach brief.

Cross-checking and common beginner traps

No single instrument tells the whole story. You’ll learn a scan: attitude, airspeed, altimeter, turn coordinator, heading, VSI, then back. In a climb, pitch and power set the speed; the VSI confirms the trend. In a turn, the turn coordinator and heading indicator work together.

• Fixating on one dial. Keep your eyes moving.
• Forgetting the heading indicator. It drifts. Reset it.
• Chasing the VSI. It lags. Make a small change and wait.
• Ignoring the ball. An uncoordinated turn costs speed and comfort.
• Wrong altimeter setting. Check QNH before every flight and every approach.

Practise partial-panel flying with your instructor. It builds confidence and shows you how the instruments support each other. Before long, the panel will feel less like a wall of dials and more like a conversation about what your aeroplane is doing.