Instrument Flight (in VMC)
Chapter 19.2
Flying by Means of Instruments
Flying without natural landmarks is called INSTRUMENT FLIGHT.
In instrument flight, there are no references outside the airplane. The flight is performed exclusively using the attitude indicator and engine instruments.
Flying by Means of Instruments
Instrument flights are performed in the following cases:
- in bad or doubtful visibility or if optical illusions are likely, during visual meteorological conditions / VMC
- when visibility is below the minimum requirements, i.e. in instrument meteorological conditions / IMC
The ATTITUDE INDICATOR / AI
ATTITUDE INDICATOR / Al represents the view from the cockpit in the direction of flight.
With a little imagination you can match this representation with the landscape in front of the aircraft.
The representation is however abstract and highly simplified:
Flight Instruments
The complete orientation of the aircraft and the direction of movement is derived from several flight instruments. These instruments are called PRIMARY FLIGHT INSTRUMENTS.
The instruments are arranged in a T shape.
Flight Instruments
The ATTITUDE INDICATOR, AI is the most important tool for instrument flight. It replaces the view from the cockpit window. By interpreting this instrument you know the attitude of the aircraft in space even without a natural horizon.
The electronic PRIMARY FLIGHT DISPLAY / PFD
An electronic representation of these flight instruments is called the PRIMARY FLIGHT DISPLAY / PFD.
The electronic PRIMARY FLIGHT DISPLAY / PFD
On the screen also, the displays are grouped in the form of a T.
Standard symbols and colors are systematically used to limit the risk of misinterpretations.
Display of the engine power / ENGINE INSTRUMENTS
Displays for engine monitoring / ENGINE INSTRUMENTS
The display panel contains instruments which display the variable values of the ENGINE POWER. These are the PRIMARY ENGINE INSTRUMENTS.
Engine thrust is not displayed directly, depending on the type of propulsion. Only the power settings are displayed. For the reciprocating engine the following parameters are used:
The RPM INDICATOR is the PRIMARY ENGINE INSTRUMENT for a fixed-pitch propeller
The MANIFOLD PRESSURE and the RPM INDICATOR are the PRIMARY ENGINE INSTRUMENTS for a CONSTANT SPEED PROPELLER
Anzeige der Triebwerkleistuņg / ENGINE POWER
ENGINE INSTRUMENTS
The instruments that indicate the state of the engine (pressures, temperatures etc.) are the SECONDARY ENGINE INSTRUMENTS.
CONTROL INSTRUMENTS / PERFORMANCE INSTRUMENTS
CONTROL INSTRUMENTS are instruments with instantaneous display (without delay).
By using the ATTITUDE INDICATOR you directly control your attitude.
By using the PRIMARY ENGINE INSTRUMENTS you directly control your power setting.
This is why these instruments are called CONTROL INSTRUMENTS.
The DIRECTIONAL GYRO also reacts instantly, but plays a secondary role in determining the flight attitude.
CONTROL INSTRUMENTS / PERFORMANCE INSTRUMENTS
PERFORMANCE INSTRUMENTS are instruments with a delayed display.
The AIR SPEED INDICATOR, VERTICAL SPEED INDICATOR and ALTIMETER indicate the current flight performance and should always be consulted in relation to other instruments. To modify their value, you should modify the attitude and / or engine power.
These instruments are PERFORMANCE INSTRUMENTS.