Cessna 172 Cockpit Einführung

Welcome to Aerofly FS and perhaps your first flight in a Cessna 172. We’re going to introduce you to the basic flight instruments first before we head out for a short local flight around the airport.

Disclaimer

Please don’t apply the information that you learned in the tutorial in the real world directly without taking real world flying lessons with a certified flight instructor. This tutorial is applicable to simulator flying only.

Overview

Looking at the main instrument panel we find the classic six-pack of the most important flight instruments which we highlighted on the screenshot. In front of you you can find the control yoke which is used to steer the aircraft in the air. At your feet you can also find rudder pedals which are used to steer on the ground and to keep the nose pointing straight in the air.

Hiding the Yoke

Behind the yoke you can find all sorts of switches, mainly for controlling the aircraft lights.

• Click at the metallic base of yoke to hide it from view.
• Click that area again to bring it back.

The “Six-Pack”

Let’s take a closer look at the most important instruments. Take your time to inspect the instruments up close. From the top left to bottom right these are:

• Airspeed Indicator (ASI)
• Attitude Indicator (AI)
• Altimeter (ALT)
• Turn Indicator
• Heading Indicator (HDG)
• Vertical Speed Indicator (VSI)

Airspeed Indicator (ASI)

The airspeed indicator uses the pitot and static pressure from small openings in the fuselage and on the wing to mechanically compute the speed of the oncoming air. This is the indicated airspeed and is typically measured in knots, giving us a speed in KIAS, knots indicated airspeed.

The more airspeed that we have the more lift the wing can theoretically produce. We usually only need enough lift to compensate the weight of the aircraft when we want to fly straight and level. If we try to fly slower and slower and we will eventually reach a point where the wing cannot generate enough lift and we can no longer fully compensate the gravitational pull. Then we either start descending or if we still try to maintain altitude we will get into a stall situation and the wing will loose even more lift relatively quickly. The airspeed at which a stall happens varies depending on the aircraft weight, the maneuvers that we fly, the flap configuration and many other factors like the current engine power and propeller wash onto the wings. And because of that fact you can’t rely solely on the airspeed to stay away from a stall. For the simple case of flying straight and level we can still give some good speed estimates for the airspeed at which the aircraft will stall.

The image on the right shows the the following situations in flight.

• Top left - A climb with 10° nose up pitch.
• Top center - A descent with 10° nose down pitch.
• Top right - A climbing right turn with 5° pitch up and 20° bank angle to the right.
• Lower left - A level turn to the left. 0° of pitch and 30° bank to the left.
• Bottom center - A steep turn to the left with 45° bank angle.
• Bottom right - A steep turn to the right with 60° bank angle and 5° nose up pitch.

Altimeter (ALT)

The altimeter is a diagram that expands and retracts as the ambient air pressure changes. It compares the pressure difference of the currently measured air pressure to a reference pressure set with an adjustment knob. The altimeter doesn’t show the altitude above sea level or above ground correctly unless it is calibrated to the current air pressure on the ground or sea level.

• Rotate the pressure setting knob in the lower left corner to adjust the reference pressure of the altimeter, indicated on the right hand side in hekto-pascals.

The correct pressure setting is given by local weather stations, automatic terminal information service (ATIS) or automated weather observing system (AWOS). In standard conditions the pressure is 1013 hPa or 29.29 inches of mercury (inHg).

The altimeter indicates the pressure difference between the set ground pressure or sea level pressure to the currently measured static air pressure. It shows the derived altitude with three needles.

The longest and thinnest needle with the triangle at the end shows the altitude in ten thousand feet increments.

The short and thick needle shows altitude in 1000 feet increments.

The long and thick needle shows increments in 100 feet.

Rate of Turn

When the airplane wings are horizontal then the airplane is not turning at all. When the left wing tip tips down to the white marker then you are flying a turn to the left at standard rate which completes a full 360° turn in two minutes. A 180° turn will take 60 seconds and a 90° turn takes 30 seconds at that turn rate.

These standard rate turns (2 minutes for a full circle) are used in instrument flying conditions to fly standard procedure turns which can be flown relatively precisely even with this one basic instrument.

Internally the turn indicator is another gyroscope that it allowed to tilt depending on the change in heading. As the nose of the airplane yaws left and right the turn indicator shows the rate of turn of the fuselage as seen from above.

The turn indicator does not shot the bank angle of the plane and it also does not show any pitch information. These can be found on the instrument directly above it, the attitude indicator.

Balance Indicator

The second and lower part of the instrument is the balance ball. This acts just like a balance scale but the tube is slightly curved upwards to the end to make it less sensitive. The ball inside the tube will be pulled down by the acceleration of the airplane and rolls to the lowest point. When we always point our nose straight into the wind the ball will be centered even if we fly turns. It is the equivalent of the forces that you feel when you sit in the airplane yourself.

When the airplane nose is not pointing straight into the wind the fuselage and vertical stabilizer as well as the propeller all will create a side forces. Sitting in the plane we can feel that we are pushed to left and right. The balance ball then also deflects left and right. To correct this we should apply rudder input to straighten out the airplane nose. Otherwise we generate extra drag and worsen the experience for passengers. Thinking of bigger airliners you can imagine it would be very uncomfortable if the flight attendant’s trolleys suddenly move left and right and bump into the passengers right next to it. Similarly in a small airplane you don’t want all of your passengers and luggage to be flung to one cabin side like they do in a car. Unlike a car the airplane is sensitive to being loaded asymmetrically and would start to roll slowly in an uncommanded fashion.

Looking at the ball, if you see it deflected you should push more of the rudder pedal where the ball is on. If the ball is on the left you apply left rudder with the left foot. When the ball is right of center you push right rudder with the right foot.

You can “kick the ball” back to neutral with your feet.

Heading Indicator

The heading indicator is a gyroscope that maintains its attitude even if the aircraft turns around it. You can think of the compass rose being stationary while the aircraft symbol turns with the actual airframe.

Directional Gyro

The heading indicator therefor shows the direction of the aircraft nose relative to the fix gyro reference. The gyro is adjusted to the known runway heading before taking off and during the flight it can also be re-calibrated using the magnetic compass on the windscreen. Aerofly FS manages this calibration for you and the heading indicator shows the correct magnetic heading for you.

Selected Heading

The heading indicator has a small heading bug that can be adjusted with the knob in the lower right corner

• Turn the heading knob to adjust the selected heading. This serves as a steering target for the autopilot and can also be used as a reference for manual flying.

When the needle deflects up then you are climbing. It shows the rate of climb in 100 feet per minute. With the needle pointing at +10 for example you are climbing at 1,000 feet per minute. Climbing from 2,000 ft to 4000 ft will take two minutes at that rate.

If the needle is pointing down you are descending and loosing altitude. For approach and landing as a rule of thumb you can use your airspeed in knots and divide that by 2 to give you the necessary sink-rate indication for a stable 3° approach angle. For an approach speed of 70 knots in our Cessna this yields roughly 350 ft/min. For 80 kt it’s 400ft/min and for 100 kt it’s 500ft/min. The actual rate required depends on other factors like wind speed and actual ground speed but this is a good estimate.

This concludes the basic six most important instruments on the Cessna 172.

Engine RPM

The engine rotation speed can be monitored on the engine tachometer which shows the engine’s revolutions per minute (RPM). On the same instrument you can also see the total time that the engine has been running, similar to the total mileage indication in your car.

With maximum power, on the ground the engine usually reaches up to 2500 RPM. In the air we may have to reduce the throttle slightly to stay below the red-line limit of 2700 RPM above which we could damage the engine and/or propeller.

On the ground we aim to keep the rotation speed above 1000 RPM to keep it running smoothly and to provide enough generator power to charge the battery. At the full idle position the generator doesn’t output enough power to and you can run the risk of draining the battery.

Throttle

The engine is throttled with a black throttle lever in the center of the panel. This adjusts the amount of air and fuel that enter the pistons and the engine power changes.

• Push the throttle lever in to open the throttle and increase engine power. This is like stepping on the gas pedal in a car but here you don’t have to stay on the throttle, it stays where you left it.
• Pull the throttle lever out to close the throttle and decrease engine power. The engine should keep running even with the throttle fully closed, similarly to your car engine.

Increasing the engine power will help us accelerate and fly faster or climb. Decreasing the engine power helps us to slow down and causes us to descent.

Mixture

The ratio of fuel to air can be fine tuned with the red mixture lever in the cockpit to adjust the engine to the environmental conditions for maximum power output or for best fuel economy.

• Push the mixture lever in to enrichen the fuel mixture. More fuel goes is mixed in and engine power increases while at sea level.
• Pull the mixture lever out slowly to lean the fuel to air mixture. Less fuel is introduced into the engine. At sea level the engine then produces less power but can be more efficient.
• Pull the mixture out completely to shut the engine off. Without any fuel the engine starves and the engine is savely shut down. After that the magneto switch is turned to OFF to prevent any spark ignition.

Ignition - Magnetos

The spark plugs which ignite the fuel receive their electric power from two rotating magnets attached to the driveshaft that induce a current in electric coils near them. When the engine is rotating these magnetos cause the spark plugs to fire. In the cockpit we can open the two electric circuits (one for each magneto) to stop the engine ignition for each side individually. The ignition key can be found in the lower left of the instrument panel and has multiple stops.

• Off - Turns both magneto switches off. The engine stops but it may still have fuel inside which could potentially ignite and spin the propeller abruptly. To safely shut down the engine you first pull out the fuel mixture, then turn off the magneto switch.
• R - Only the right hand side magneto circuit is closed and the engine can continue to run. The left one is disabled. This position is used to test the right hand side.
• L - Only the left side is closed. The right one is disabled. This position is used to test the left hand side.
• Both - This position is used during the entire flight to have dual redundancy. Even if one circuit were to fail the engine can keep running as long as there is fuel reaching the engine.
• Start - Both magnetos are engaged and the electrical starter is energized. This spring loaded position is used to start the engine and the ignition key is released right after the engine starts. This works the same as in your car.

Flaps

Behind the right hand yoke you can find the flap lever. This lever selects the desired flap positions: up, 10°, 20° and 30°. The more flaps you have the slower you’ll be able to fly. With extended flaps you can’t fly as fast because the drag is high and because you could also damage the flaps at high speeds. Because of the additional drag you will need more power and you cannot climb as steep and not as quickly.

• On touch devices simply hold the finger down on the flap lever and slowly move it down to extend flaps.
• With a mouse you can either hold down the left mouse button and move the mouse down OR just use the scroll wheel
• With VR hands you can grab the lever and move it with your virtual hands.

Parking Brake

On the ground, if we don’t want to push the left and right foot on the rudder’s break pedals all the time we can use the parking brake. The parking brake is a lever under the front panel between the knees of the pilot.

• Click on the lever to set the parking brake. The lever can be pulled out with VR hands.
• Click the lever again or push it forwards to take the parking brake off.

Pitch Trim

In the center, below the front panel you can find a large wheel. This trim wheel is rotated in the direction that you want the airplane nose to move. By rotating this wheel you can deflect a small aerodynamic trim tab on the elevator that alleviates the control yoke elevator forces.

You’ll need to trim the aircraft after you increased the speed or when you changed the engine power setting.

• Grab the wheel with your mouse cursor or use the mouse wheel to rotate it.
• With a touch device you can just swipe the wheel with your finger.
• With VR hands you can grab the wheel and spin it and also move it by touching it with the virtual finger and moving the hand.

Fuel System

Fuel Pump

The electric fuel pump increases the fuel delivery pressure to the engine. This ensures a continuous fuel delivery even during abrupt maneuvers on the ground. The fuel pump is turned on before takeoff and can be turned off during flight to save wear. Before landing it is turned on again and can be turned off after safe landing. The fuel pump switch is located on the front panel in the electric switching panel often hidden by the pilot’s yoke.

• Hide the yoke if necessary by clicking on the silver base of the yoke.
• Set the fuel pump switch before takeoff or landing to on by clicking on it or by using the mouse wheel.

Fuel Selector

The fuel pump delivers more fuel than the engine needs. The excess fuel is returned to only to the right hand fuel tank which means the left one empties a bit quicker over time. Because this could cause a significant imbalance over time you can turn off the fuel delivery from the emptier tank and only use the most fullest tank. When enough fuel has been consumed so that the imbalance no longer exist you can turn the fuel selector back to both, enabling both fuel tanks to be used.

• Grab the fuel selector and move it to the left position to use the left hand fuel tank.
• Move it to the center “BOTH” position to use left and right fuel tanks simultaneously.
• Move it to the right position to enable only the right hand fuel tank.

Fuel Shut-Off

The fuel shut of valve is positioned near the fuel selector.

• Pull the lever out to stop fuel delivery to the engine. The engine will eventually starve and shut down after it’s small feeder tank has been emptied.

Electrical Switches

Behind the pilot’s yoke there are many switches that control electric systems on the aircraft.

Remember you can click on the base of the yoke to hide it!

• MASTER BAT - The red switch turns on the battery and provides electricity to essential systems.
• MASTER ALT - The alternator is the engine driven electric generator. When the engine is running it provides electric power to charge the battery and to the systems. Turning it on sets the master battery switch to on as well. Turning it off disables the generator power and the battery starts discharging.
• AVIONICS MASTER 1/2 - Turns avionics devices on/off.

Internal Lighting

Two rotary knobs control the brightness of the radio/panel integrated lighting as well as the glare-shield/pedestal flood illumination.

• Use the mouse wheel to adjust the internal lights.
• With VR hands grab the knob and rotate your hand
• On touch devices tap on the knob, a green ring appears. Move your finger on the green ring around the knob to turn it.

Communication Radios - COMMs

Communication with the air traffic controller and with other airplanes in the vicinity is done via radio signals. Air traffic control frequencies can be obtained from airport charts and public databases.

To tune a communication frequency in the Cessna 172 we first have to dial in the frequency and then activate it.

• Rotate the small and large knobs on the COM1 panel to set the desired frequency.
• Push the swap arrow button to transfer your entry to the active frequency to tune the transceiver.

Navigation Radios - NAV1/NAV2

The Cessna 172 has two separate navigation receivers: NAV1, tuned with the upper radio panel and NAV2, tuned with the lower panel. These receivers are able to pick up signals from VOR or ILS ground stations used for instrument navigation in low visibility.

• On the right side of the upper COM/NAV unit rotate the large and small knobs to set the standby navigation frequency.
• When the desired frequency has been set push the swap push-button to transfer the frequency to the active side and to tune the NAV-receiver.

When within range the course deviation indicator shows a needle deflection, otherwise it shows red OFF flags.

Distance Measurement Equipment (DME)

The distance measurement equipment (DME) sends a signal to the ground station and then measures the time it takes for the signal to be send from the ground station back to you. Knowing the speed at which the radio waves travel, the speed of light, the distance to the station can be computed from the time delay.

Automatic Direction Finder (ADF)

The automatic direction finder (ADF) is a device that can detect where a radio beacon is coming from. It only shows the direction to/from the station and doesn’t provide any distance information.

• Turn the knobs on the right hand side to set the standby ADF frequency
• Push the FREQ/Swap button to activate the frequency.

Transponder (XPDR/ATC)

The transponder is a device that sends the aircraft identification and altitude to the air traffic control ground receivers. ATC can then identify you on their radar screen and provide accurate instructions or assistance.

The transponder is usually turned on before taking off and turned off after landing unless otherwise required for tracking aircraft during taxi at larger airports.

ATC assigns each aircraft a certain squawk code. The pilot enter this code into the transponder and when instructed activates the identification function which highlights the airplane on the ATC radar screens.

• Enter the four digits code by pushing the buttons at the bottom.
• Use the clear button to remove the last digit if you typed the wrong digit.
• Push the VFR button to set the code 1200 or 7000 depending on the region’s general code.

To set the transponder mode from off to ON or to ON&ALTitude reporting

• Rotate the knob on the right to ALT to send all required data to ATC.
• Set the mode to SBY (standby) to disable the transponder but to keep the device screen on. The transponder is then no longer transmitting and ATC can no longer identify you on the radar screens (their radars may show an unknown aircraft).
• Set the knob to OFF to turn the transponder off completely.

Heading Select (HDG)

In the bottom right of the horizontal situation indicator (HSI) or heading indicator you can find the heading bug. Rotate this knob to select a target heading on the compass rose.

• To activate the heading select mode can be pressing the HDG button on the autopilot panel.
• Press the HDG button again to deactivate it.

Navigation Mode (NAV)

The autopilot can track a VOR or ILS signal. For this you need to tune a station first and then set the course and arm the capture.

• Select the frequency of a nearby VOR station with in the NAV1 panel.
• Transfer the selected standby frequency to the active with the NAV1 swap button.
• Rotate the OBS1 knob to set the desired radial.
• If you are not already flying towards the VOR radial select a heading with the heading knob, then engage the heading mode first with the HDG button to fly roughly in the right direction.
• Then arm the CDI capture by pressing the NAV button on the autopilot panel.

Once captured the autopilot will try to center the course deviation indicator (CDI) needle.

• Push the NAV button again to disarm the NAV capture or to disable the NAV mode if already engaged.
• If the mode was already engaged and you turn it off the autopilot switches back to attitude hold mode.

Vertical Speed Hold (VS)

When engaged the vertical speed mode (VS) holds the current vertical speed. Note - You are in control of airspeed, make sure to adjust power.

• Push the VS button to activate the vertical speed mode.
• Use the UP/DOWN buttons to change the target vertical speed.
• Push the VS button again to deactivate this mode.

Altitude Hold (ALT)

This mode maintains the altitude at the time of engagement. The autopilot will pitch up and down to try and stay at that altitude.

• Push the ALT button to engage altitude hold mode. The airplane will fly back to the altitude that you had when you pushed the button.
• Push the ALT button again to disable the altitude hold mode.

The autopilot will automatically switch to the altitude hold mode when you reach the selected altitude in pitch hold (PIT) or vertical speed hold (VS) mode.

• Rotate the large and small knobs on the autopilot panel to change the selected altitude in 1000ft and 100ft increments respectively.
• Push the ARM button to arm the altitude capture mode.
• Push the ARM button again to disarm altitude capture upon reaching the selected altitude.

Autopilot Approach Mode

The approach mode has to be armed and captured similarly to the lateral only NAV mode. The key difference is that the autopilot will also try and capture the vertical steering from the NAV1 receiver and follow the glide slope of the ILS.

• Tune an ILS using the NAV1 panel.
• Set the ILS course with the OBS1 knob.
• Turn the aircraft to an intercept heading using the HDG knob and autopilot HDG push-button
• Arm the approach mode by pressing the APPR button.

After capturing the localizer signal the autopilot arms the glide slope capture. Monitor the engagement of the lateral and vertical LOC and GS modes and reduce power to maintain the desired airspeed once the glide slope is activated.

• Push the APPR button again to disarm the ILS capture
• If already engaged the autopilot will revert to attitude hold mode and maintain pitch and bank.