All The Elements Of An Aircraft Cockpit

The Elements of an Aircraft Cockpit

Cockpit instrument distribution varies from one aircraft to another, but usually the distribution is the same and shares many similarities. Understanding cockpit instrument layout will be a first essential step in our journey into aviation and instrumental flight. 

Basic controls

Our basic device for controlling our aircraft will be our yoke, sometimes also called control column. It can be presented in the form of a “steering wheel” or a control stick located either in front of the. Each pilot will have its own yoke and usually they will be mechanically connected to move accordingly. The yoke will mechanically move our ailerons and elevators. In the yoke, usually we will find a button to start communicating and sometimes even a switch to control our pitch trim. In aircrafts equipped with autopilot, we may also find a button to quickly disengage it.

In heavier aircrafts, as the forces required to move our control surfaces are too big and require the use of hydraulic systems, our yoke will function with a fly-by-wire system. The yoke will send an electrical signal to computers that will determine the required surface deflection and will order hydraulic actuators to act accordingly. The main problem with fly-by-wire is the lack of feedback and being unable to feel the pressure we are putting on our control surfaces. For this, many yokes are equipped with features that adjust the resistance and pressure required to move our yoke and stick shakers and stick pushers to prevent our aircraft from stalling.

Our other device we will use to control our plane will be the pedals. Pedals are used for yaw and braking. By pushing our pedals, we will make the aircraft yaw and they will also be used to manoeuvre on the ground. If we apply pressure only to the top, we will push the brakes. A common mistake when using our pedals on ground is to apply pressure on our brakes without noticing, degrading our tires and our brakes and slowing us down. The best way to avoid it, is to put your heels on the floor and control the pedals while applying pressure with your toes on the lower part of the pedals. If we want to brake, we will lift our feet and press with our toes the upper part of the pedals. 

Trims will be controlled by either a wheel or a switch, and they will usually be located between both pilots or below the control column of the captain’s seat. Flaps will be operated by a switch that will usually feature a position for each flap setting. 

Landing gear will be operated with a safety switch preventing it from unintentional operation. It will work in combination with 3  green lights and a red light. 3 green lights will mean our landing gear is down and locked, while a red light means the landing gear is currently retracting or extending. This lights should be tested before each flight. Many landing gears will also feature a warning sound that will trigger if our landing gear is not extended and our power setting is below a certain value.

Flaps will be controlled with a switch that may feature either positions for each flap setting or a position for increasing and decreasing the flap angle. Along with the Flaps switch, we will find a flap indicator. In glass cockpits, flap indication will be provided by the Electronic Centralised Aircraft Monitor (ECAM), along with other information like engine parameters and position of spoilers, slats and other devices. Flaps should be checked in each position before flight.


Engine control

Our devices for controlling our engine are located between both pilots. It can be found in the form of levers of precision flight controls, in the form of a stick that we can either push or pull or rotate to allow for small precision changes.


  • Throttle: It will be used to control either the manifold pressure or the engine rpm, in aircrafts not equipped with a constant speed propeller. It will usually be in black.

  • Mixture: Used to change the ratio of air/fuel entering our cylinders. Usually as we get higher, we will have to decrease our air/fuel ratio to adjust for the lower air density and safe fuel. We will also use this lever to prime our aircraft when it’s not equipped with a fuel pump, allowing fuel to enter the cylinder before starting it. It will usually be in red.

  • Propeller: On aircrafts equipped with a propeller governor, the aircraft will feature a blue lever, used to increase the angle of attack of the propeller blades. This lever will adjust a spring inside the governor which will change the oil pressure coming from the engine, changing the angle of attack of the propeller blades. This will change the resistance it has, changing our RPM accordingly. If we change our power setting, so will our oil pressure inside our governor and our RPM will not change. This will allow us to put the propeller blades at the most efficient angle for each power setting. Propeller governors should be tested before each flight to detect malfunctions. When reducing your power, always reduce first your throttle output and then your propeller. In case of increasing your power, first increase your propeller and then your throttle. This is to increase our governor’s useful life and avoid damage due to excess pressure inside of the governor. 

Apart from this, our other devices used to control our piston engine are:


  • Fuel selector. Usually located between both pilots. In aircrafts with 2 or more engines we will also find a crossfeed fuel system.
  • Magnetos: We will have 2 magnetos for each engine. Each one of them has to be tested before flight in the engine run up, to detect possible malfunctions. We will always use both at the same time. They will usually be located on the left side of the cabin.
  • Starter. Used to start and restart the engine, it is located on the left side of the cabin.
  • Carburettor heating. In engines equipped with a carburettor, sometimes we will find a switch or a lever to heat up the air entering the carburettor and prevent icing formation inside it, which may cause an engine failure. Be aware that the higher air temperature means also lower density, so our engine power will decrease. Due to this, it should be only used in low temperature conditions that will be stated in your aircraft’s operating handbook.
  • Fuel pump. Used to activate an electrical fuel pump. It will be used for starting or restarting your engine, some emergency procedures and certain parts of your flight, in accordance with your pilot’s operating handbook.
  • Cowl flaps. Used to open a small door on the bottom of the engine cowling that allows for increased airflow, decreasing the temperature of our engine. This may be required in certain parts of the flight that require higher engine power, like take-off, go-around and climb. It is also required to open it during taxi, as the decreased airflow when compared to flying could overheat our engine.

Apart from that, we will find parameters for manifold pressure, Cylinder Head Temperature (CHT), oil pressure and temperature, fuel pressure, fuel quantity, vacuum gauge and a tachometer for RPM. In modern aircraft with glass cockpit, this information may be given by systems like the Electronic Centralised Aircraft Monitor (ECAM).

An aircraft with turboprop engine(s) has two engine control levers. A power lever and a condition lever. The power lever will be used to increase or decrease the power by scheduling the fuel for combustion while the condition lever controls the propeller RPM by varying its blade angle.

Turbofan engines will only feature one lever. As it’s functioning is more complex, we will adjust the power level with it and an Engine Control Unit (ECU) or Full Authority Digital Engine Control (FADEC) will determine the changes needed to adjust to the required power input.

Our most important parameters here will be Exhaust Gas Temperature (EGT), N1, N2 and Engine Pressure Ratio (EPR).

Many turboprop, turbofan and jet engines will also feature engine reversal, useful for decreasing our landing speed. This will be usually activated by pulling our throttle backwards.


Instrument panel

In front of each pilot, you will find your flight instrument. Your basic set of instruments will be the basic T, consisting of an airspeed indicator, attitude indicator, altimeter and heading indicator. Apart from that you will find a Vertical Speed Indicator (VSI), Turn Coordinator, a clock, a chronometer and navigational instruments like  Horizontal Situation Indicator (HSI), Omni-Bearing Indicator (OBI), Automatic Direction Finding (ADF), Global Positioning System (GPS), Automatic Dependent Surveillance (ADS) and a compass used for calibrating our heading indicator before flight and for use in case of loss of heading indication. 

 Our navigational instruments will be set up from the avionics panel. There we will change the frequencies for navigation and communications, and we will also find our transponder.

In glass cockpits, these instruments will be replaced by the Electronic Flight Instrument System (EFIS), consisting of Navigation Display (ND) and Primary Flight Display (PFD) or by an advanced GPS like Garmin 1000. EFIS will be controlled by the use of the EFIS control panel, located on top of the instrument panel. Here we will change what information we see and how it is displayed.

If our aircraft is equipped with a Flight Management System (FMS), this will be controlled by the Multi-Control Display Unit (MCDU), located between the seats of both pilots. MCDU features a keyboard and a display and here we will insert all the information of our aircraft’s performance and navigation, among other things. 

We will review each one of these instruments and how to operate them in further chapters.

Many complex aircrafts will also feature an overhead switch panel. Here we will usually find controls for Auxiliary Power Unit (APU), lights, wipers, oxygen, Inertial Reference System (IRS), anti-ice, pressurisation and emergency switches for managing emergencies like fires and smoke.

Electrical systems

Our basic switches for our electrical system will be for turning on our battery and our alternator and will usually be located below the instrument panel.  Each alternator will usually feature a warning light. Some aircrafts with more than one engine will also feature a switch for switching between voltage regulators. Both voltage regulators and alternators warning light should be tested before each flight

Modern aircrafts will also feature an auxiliary power unit (APU). APU is basically a small jet engine located on the tail of the aircraft, that will provide us with electricity for start-up and will work also as a back-up in case of loss of electrical power.

Your aircraft will also feature parameter instruments like voltmeter, ammeter and loadmeter.

Below the instruments panel, you will usually find your circuit breakers and electrical fuses. Remember to check they are all in before your flight!

Other switches


  • Light switches. Usually located below or above the instrument panel. We will find switches for taxi, navigation, beacon and landing lights.

  • Pitot heat: It will activate an electrical resistance in our pitot probes that will heat it and prevent icing. This should be checked before each flight by turning it on and after that check for deflections in our ammeter.

  • Propeller de-icing: Works the same way as pitot heat, only with propeller blades.

  • De-icing boots: If we are accumulating ice in the leading edge of our wings, this device will inflate a rubber band along the leading edge, breaking ice in the process. You should check them before each flight by inflating them and checking the vacuum gauge.

  • Fluid de-icing: It activates a pump that will spray with a deicing fluid the most vulnerable parts of our aircrafts, like the propellers and the leading edge. Sometimes instead of a spray, the fluid will emerge from very small holes located on the surface. Usually the fluid used will be ethylene glycol.

Alternate air static source

Many aircrafts will also feature an alternate static air source, in case your main static air source is blocked so you don’t lose altitude, airspeed and rate of climb/descent indication. However, all the air flowing around our aircraft produces a vacuum effect that will suck air from our cabin. In consequence, our cabin pressure is slightly lower. This causes our altitude and airspeed  indication to be higher than it should be. Also, our VSI will show a brief climb until it has adjusted to the new pressure.

In aircraft not equipped with an alternate static air source, we can break the glass of one of our instruments to allow for static air to enter. Our best option is to break the glass of the VSI, as it is the cheapest instrument to repair and the least important, as there is a risk that this procedure makes the instrument useless. However if after breaking the glass it keeps working, be aware that the air is now flowing backwards the indication will work in the opposite way, showing a rate of descent when climbing and a rate of climb when descending.

Mandatory on-board equipment

Apart from the documents stated in a previous entry, it is mandatory to always carry a first aid kit and a fire extinguisher. These Items have to be inspected every year. It is mandatory to check that these two items have been inspected in the last year and that it’s up to date before each flight.

Life-jacket will be mandatory when flying  single-engine aircrafts over water at such a distance that in case of an engine failure, it would not be possible to glide and land in terrain, or when operating at aerodromes where in the opinion of the pilot-in-comand, it would be possible to ditch during approach or landing.

 For multi-engine aircrafts, it will be mandatory when flying overseas at a distance greater than 30 minutes at normal cruise speed or 50 NM, whichever is less.

Oxygen will be required in case we expect to be more than 30 minutes at an altitude between 10.000 ft and 13.000 ft, or for the entire time we are flying at an altitude higher than 13.000 ft.

It will also be required to carry spare electrical fuses for each type of fuse our aircrafts features.

 

- Jose Luis Pérez-Íñigo Martens


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