As a first entry into the journal, I wanted something substantiate and something about aviation. Listening to people not familiar with aircraft operations, I have noticed that there is one source of confusion that is recurrent: Visual Flight Rules and Instrument Flight Rules. There are some subtle differences between the two and if not understood correctly, the whole concept of visual flight might be difficult to grasp.
VFR and IFR
VFR stands for Visual Flight Rules and IFR stands for Instrument Flight Rules. These are two different sets of regulation concerning flight. You are either flying under VFR or under IFR and the good news is that those two sets are acknowledged worldwide. Well almost…bar the UK but what are the Brits doing like anybody else?
VFR
Visual Flight Rules mean that your flying is done using visual cues from the outside. In other terms, you are using the horizon to maintain pitch, roll and yaw control and you are using landmarks on the ground for navigation. You barely need any instrument even though the rules require at least an airspeed indicator, an altitude indicator and a magnetic compass. This is because the airspeed, altitude and heading cannot be easily inferred in flight.
However this does not mean that the pilot shall not use other instruments. If the instruments are there on the dashboard, it would be foolish not to use them for navigation. These are nonetheless no primary instruments but what is called supportive instruments.
These rules are the ones used by the vast majority of general aviation pilots all over the world.
IFR
Instrument Flight Rules are a set of rules that allows the pilot to fly only by reference to his instruments. Consequently more instruments are required to fly and the requirement consists of an airspeed indicator, an altitude indicator, a compass, a turn coordinator, a gyroscopic attitude indicator, a clock, a two way radio and an adequate navigation equipment. That’s a whole lot more but this is the price to pay to bust clouds. In return, you are allowed to fly without reference to the horizon which means into haze, fog and clouds.
Instrument flying is more demanding mentally than visual flying and requires perpetual concentration by the pilot. However, navigations are a lot easier because contrary to landmarks that may or may not be seen, navigation information provided by instruments is not subjective.
These rules are the ones used by all airlines' pilot as well as a minority of general aviation pilots. This is especially true in Europe where the cost of IFR flying is usually prohibitive. It is a pity as instrument flying with proper experience is regarded as very safe.
VFR and VMC, IFR and IMC
VMC stands for Visual Meteorological Condition and IMC for Instrument Meteorological Condition. This is used to describe the weather. Indeed, visual flight rules stipulate minimum requirements in term of visibility and ceiling to be able to fly. If those minima are met, the weather is VMC. If not, the weather is IMC.
This only suggests which set of rule to use for flying. For instance, when the weather is VMC, a pilot can elect to fly under VFR or IFR. However when IMC is prevailing, a pilot must fly IFR.
A good example is airlines' pilots who are constantly flying under the instrument set of rules whatever the weather might be. On the other hand, many general aviation pilots are grounded as soon as the weather deteriorates because they are not properly qualified to perform a flight under IFR.
VFR at night
Night flying is not restricted to instrument rated pilots contrary to what one might think. At night the horizon may still be visible and may be used for attitude reference while city lights, antenna lights and roads make good visible cues.
Final Words
Finally a good example of the differences between the two regimes of flights may be seen on the charts used by pilots. The charts shown below depicts the exact same area of Atlanta and are drawn at the same scale.
VFR charts as shown in the link below contain a lot of landmark information and topographic information. Antennae, cities, airports, lakes, river....
VFR and IFR
VFR stands for Visual Flight Rules and IFR stands for Instrument Flight Rules. These are two different sets of regulation concerning flight. You are either flying under VFR or under IFR and the good news is that those two sets are acknowledged worldwide. Well almost…bar the UK but what are the Brits doing like anybody else?
VFR
Visual Flight Rules mean that your flying is done using visual cues from the outside. In other terms, you are using the horizon to maintain pitch, roll and yaw control and you are using landmarks on the ground for navigation. You barely need any instrument even though the rules require at least an airspeed indicator, an altitude indicator and a magnetic compass. This is because the airspeed, altitude and heading cannot be easily inferred in flight.
However this does not mean that the pilot shall not use other instruments. If the instruments are there on the dashboard, it would be foolish not to use them for navigation. These are nonetheless no primary instruments but what is called supportive instruments.
These rules are the ones used by the vast majority of general aviation pilots all over the world.
IFR
Instrument Flight Rules are a set of rules that allows the pilot to fly only by reference to his instruments. Consequently more instruments are required to fly and the requirement consists of an airspeed indicator, an altitude indicator, a compass, a turn coordinator, a gyroscopic attitude indicator, a clock, a two way radio and an adequate navigation equipment. That’s a whole lot more but this is the price to pay to bust clouds. In return, you are allowed to fly without reference to the horizon which means into haze, fog and clouds.
Instrument flying is more demanding mentally than visual flying and requires perpetual concentration by the pilot. However, navigations are a lot easier because contrary to landmarks that may or may not be seen, navigation information provided by instruments is not subjective.
These rules are the ones used by all airlines' pilot as well as a minority of general aviation pilots. This is especially true in Europe where the cost of IFR flying is usually prohibitive. It is a pity as instrument flying with proper experience is regarded as very safe.
VFR and VMC, IFR and IMC
VMC stands for Visual Meteorological Condition and IMC for Instrument Meteorological Condition. This is used to describe the weather. Indeed, visual flight rules stipulate minimum requirements in term of visibility and ceiling to be able to fly. If those minima are met, the weather is VMC. If not, the weather is IMC.
This only suggests which set of rule to use for flying. For instance, when the weather is VMC, a pilot can elect to fly under VFR or IFR. However when IMC is prevailing, a pilot must fly IFR.
A good example is airlines' pilots who are constantly flying under the instrument set of rules whatever the weather might be. On the other hand, many general aviation pilots are grounded as soon as the weather deteriorates because they are not properly qualified to perform a flight under IFR.
VFR at night
Night flying is not restricted to instrument rated pilots contrary to what one might think. At night the horizon may still be visible and may be used for attitude reference while city lights, antenna lights and roads make good visible cues.
Final Words
Finally a good example of the differences between the two regimes of flights may be seen on the charts used by pilots. The charts shown below depicts the exact same area of Atlanta and are drawn at the same scale.
VFR charts as shown in the link below contain a lot of landmark information and topographic information. Antennae, cities, airports, lakes, river....
On the other hand, IFR charts such as the one shown below are slightly more austere and only show airports, navigation beacons and airways in between.
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