5 ms·

What's IFR and VFR?

chrisandchris 3y ago
Instrument and Visual Flight Rules; flight using basically only instruments, or relying on visual sight of things
krisoft 3y ago
chrisandchris described it perfectly. I will just add some additional info. (Funnily enough my name is Krisz :) so you will have info from chrisandchris and Krisz ;)) VFR is the type of flying everyone starts at first with, and then later in your training you learn IFR. There are generally 3 big “problems” a pilot has to solve. They have to keep the plane flying straight and level, they have to keep from hitting things (other airplanes, terrain, buildings, etc), and they have to get to where they want to go. The two types of flying differs in how these 3 big goals are achieved. With VFR you look out the window and see if the horizon is level, and that you are not sinking or ascending to keep level and straight flight. You sometimes crosscheck this with your instruments but the windscreen and your vestibular system is your primary instrument. You avoid flying into things by what is called “see-and-avoid”, which is exactly what you imagine. You see things and you avoid them. You use your radio to be aware of other airplanes around you, but your primary means of avoiding them is still the fact that you see them and steer away from them. And finally you get to where you want to be by looking out finding landmarks and flying to your destination based on that. For example you might spot a river, or a big road and follow it to your destination. This is what we call visual flight rules, or VFR for short. This is all great and very intuitive. But the problem is that none of this works if you can’t see out of the airplane! And that happens more often than you would like. Fog and clouds and mist and darkness has caused many accidents before more advanced piloting techniques were developed. So what do we do if we can’t see? We fly using the instruments in our cockpit, and this process is called instrument flying rules or IFR for short. You keep the airplane straight and level by scanning the instruments and integrating what they say in your head and reacting accordingly. This is harder than it sounds. One tricky thing is that your inner ear in the absence of visual inputs lies to you! You might feel you are ascending when you are actually banking . The other tricky thing is that there is a certain amount of lag on the airplane’s reaction to your inputs and there are random noises like tiny gusts of wind, so if you yank the controls every time you see the instruments change immediately then you yourself might induce oscillations in the airplane. And then you react to those oscillations and if your reactions are in phase things might get worse and worse. So you have to learn to not do that, and also to trust the instruments more than your own internal sense of orientation. Which is very non intuitive and therefore hard. Then you also have to avoid hitting things. The way you avoid hitting cranes, buildings and terrain is by flying above a certain minimum altitude. As you might guess this minimum is higher where the ground is higher and lower where it is lower. And then you also have to know about tall towers. There are maps which advertise how high you have fly to avoid hitting obstacles at any point. Avoiding other airplanes is harder, so you use the help of the air traffic control. They clear you to fly certain directions at certain elevations and they make sure every airplane they control stays far away from each other. And of course both of these depend on you knowing where you are and where you are heading. Having a map of minimum safe altitudes is nice but if you don’t know where you are it is near useless. Having clearances is nice, but if you don’t know which way you are flying they won’t help you. So you use a compass, and radio navigational instruments to keep track of where you are. This is a lot of hard work and you have to do all of the above and more simultaneously at the same time and without major errors. So if you are not good enough at each of them you might become what is known as “task-saturated”. Too many things to do and keep all in your head. Or if you are not processing all of this in your head fast enough your internal representation of what is going on with the airplane and around the airplane might lag behind reality. This is also known informally as “flying behind the airplane” which is for obvious reasons very dangerous. So IFR is much harder than VFR, but also because it is less about your internal feelings and your ability to look around it is also much easier to simulate in a simulator. This is the reason why it is generally recommended to start with VFR training in a real airplane, while in the later IFR training simulators can play a bigger role.
- jen729w 3y ago
  Bloody marvellous, and I know I should just upvote to express how bloody marvellous I think this is, and I’ve done that, and it didn’t feel like enough, so here I am. It’s Christmas, shoot me.
- gkedzierski 3y ago
  "your vestibular system is your primary instrument" This was a big no-no during my training. You are very prone to spatial disorientation and vestibular system illusions like leans, somatogravic illusion, etc. I was always taught (in the books and during flights) to trust the aircraft instruments. (I trained in the UK)
  - MaxBarraclough 3y ago
    They're talking about flying VFR. You can't get the leans or somatogravic illusion flying in daytime VMC. An attitude indicator is not required for VFR-only aircraft.
    - krisoft 3y ago
      You are right, but I believe gkedzierski is right too. It is indeed common for trainers to start telling these things to student pilots early on during their training. I think the reasoning behind that is to instil the right instrument scan practices while people are fresh in the cockpit before they even consider IFR training. > You can't get the leans or somatogravic illusion flying in daytime VMC. You are 100% correct on that. Just to explain to others reading us: VMC means visual meteorogical conditions. Roughly and informally that is when you can see. While IMC would be instrument meteorological conditions, that is roughly and informally when you can't. Just to illustrate how dangerous these "leans" can be there is this NTSB report about such a case: https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR2101.pdf https://www.ntsb.gov/investigations/AccidentReports/Reports/... People might also know this one as the tragic helicopter accident which killed Kobe Bryant. The pilot had 8,577 hours of total flight time, and he was the chief pilot of the company. So you would count him as an experienced pilot. Yet as he flew into thick fog, according to the NTSB report, he got the "leans". That is he had the illusion that he was ascending while in reality his airplane was banked and turning. Sadly they flow into a hillside and all 9 people aboard died. A tragic case. It is hard to know exactly when the pilot lost all visual cues but according to the report there was about a minute between the pilot reporting to ATC that they are climbing to get over the clouds and them impacting the terrain. Things unfortunately can go sideways very fast in IMC.
inoffensivename 3y ago
Simply put: VFR, Visual Flight Rules, you can see outside, you must stay outside clouds, it's your job to not hit other planes and the ground. You do this primarily by looking out the window. IFR, Instrument Flight Rules, you are in the clouds and can't see outside, it's air traffic control's job to keep you away from other airplanes and the ground. You keep the plane under control by using your instruments only. Looking out the window yields no information. :-)
- kqr 3y ago
  Is ATC really responsible for terrain separation? I was under the impression they can advise you when your altitude looks odd, but you are still responsible for avoiding terrain by following procedures and sticking to minimum altitudes, etc.
  - alistairSH 3y ago
    The pilot is in control. But ATC will provide an altitude they want you to maintain. When you are cleared to land, ATC isn’t doing anything to keep the plane from hitting a building on final approach.
  - tass 3y ago
    They will provide “clearances” which avoid terrain - if they ask you (for example) to fly direct to LAX, they need to ensure you are told an altitude to fly which keeps you at or above the minimum for whatever is between you and that waypoint. As the pilot you are required to follow the instruction but ATC aren’t responsible for you not doing so. There are situations where you may inadvertently lose communications, so ATC can’t tell you to climb for some future higher altitude requirement. In this case the pilot needs to climb and fly the minimum for the area they are in or airway they are following.

What's IFR and VFR?

Instrument and Visual Flight Rules; flight using basically only instruments, or relying on visual sight of things

chrisandchris described it perfectly. I will just add some additional info. (Funnily enough my name is Krisz :) so you will have info from chrisandchris and Krisz ;)) VFR is the type of flying everyone starts at first with, and then later in your training you learn IFR. There are generally 3 big “problems” a pilot has to solve. They have to keep the plane flying straight and level, they have to keep from hitting things (other airplanes, terrain, buildings, etc), and they have to get to where they want to go. The two types of flying differs in how these 3 big goals are achieved. With VFR you look out the window and see if the horizon is level, and that you are not sinking or ascending to keep level and straight flight. You sometimes crosscheck this with your instruments but the windscreen and your vestibular system is your primary instrument. You avoid flying into things by what is called “see-and-avoid”, which is exactly what you imagine. You see things and you avoid them. You use your radio to be aware of other airplanes around you, but your primary means of avoiding them is still the fact that you see them and steer away from them. And finally you get to where you want to be by looking out finding landmarks and flying to your destination based on that. For example you might spot a river, or a big road and follow it to your destination. This is what we call visual flight rules, or VFR for short. This is all great and very intuitive. But the problem is that none of this works if you can’t see out of the airplane! And that happens more often than you would like. Fog and clouds and mist and darkness has caused many accidents before more advanced piloting techniques were developed. So what do we do if we can’t see? We fly using the instruments in our cockpit, and this process is called instrument flying rules or IFR for short. You keep the airplane straight and level by scanning the instruments and integrating what they say in your head and reacting accordingly. This is harder than it sounds. One tricky thing is that your inner ear in the absence of visual inputs lies to you! You might feel you are ascending when you are actually banking . The other tricky thing is that there is a certain amount of lag on the airplane’s reaction to your inputs and there are random noises like tiny gusts of wind, so if you yank the controls every time you see the instruments change immediately then you yourself might induce oscillations in the airplane. And then you react to those oscillations and if your reactions are in phase things might get worse and worse. So you have to learn to not do that, and also to trust the instruments more than your own internal sense of orientation. Which is very non intuitive and therefore hard. Then you also have to avoid hitting things. The way you avoid hitting cranes, buildings and terrain is by flying above a certain minimum altitude. As you might guess this minimum is higher where the ground is higher and lower where it is lower. And then you also have to know about tall towers. There are maps which advertise how high you have fly to avoid hitting obstacles at any point. Avoiding other airplanes is harder, so you use the help of the air traffic control. They clear you to fly certain directions at certain elevations and they make sure every airplane they control stays far away from each other. And of course both of these depend on you knowing where you are and where you are heading. Having a map of minimum safe altitudes is nice but if you don’t know where you are it is near useless. Having clearances is nice, but if you don’t know which way you are flying they won’t help you. So you use a compass, and radio navigational instruments to keep track of where you are. This is a lot of hard work and you have to do all of the above and more simultaneously at the same time and without major errors. So if you are not good enough at each of them you might become what is known as “task-saturated”. Too many things to do and keep all in your head. Or if you are not processing all of this in your head fast enough your internal representation of what is going on with the airplane and around the airplane might lag behind reality. This is also known informally as “flying behind the airplane” which is for obvious reasons very dangerous. So IFR is much harder than VFR, but also because it is less about your internal feelings and your ability to look around it is also much easier to simulate in a simulator. This is the reason why it is generally recommended to start with VFR training in a real airplane, while in the later IFR training simulators can play a bigger role.

jen729w 3y ago
Bloody marvellous, and I know I should just upvote to express how bloody marvellous I think this is, and I’ve done that, and it didn’t feel like enough, so here I am. It’s Christmas, shoot me.
gkedzierski 3y ago
"your vestibular system is your primary instrument" This was a big no-no during my training. You are very prone to spatial disorientation and vestibular system illusions like leans, somatogravic illusion, etc. I was always taught (in the books and during flights) to trust the aircraft instruments. (I trained in the UK)
- MaxBarraclough 3y ago
  They're talking about flying VFR. You can't get the leans or somatogravic illusion flying in daytime VMC. An attitude indicator is not required for VFR-only aircraft.
  - krisoft 3y ago
    You are right, but I believe gkedzierski is right too. It is indeed common for trainers to start telling these things to student pilots early on during their training. I think the reasoning behind that is to instil the right instrument scan practices while people are fresh in the cockpit before they even consider IFR training. > You can't get the leans or somatogravic illusion flying in daytime VMC. You are 100% correct on that. Just to explain to others reading us: VMC means visual meteorogical conditions. Roughly and informally that is when you can see. While IMC would be instrument meteorological conditions, that is roughly and informally when you can't. Just to illustrate how dangerous these "leans" can be there is this NTSB report about such a case: https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR2101.pdf https://www.ntsb.gov/investigations/AccidentReports/Reports/... People might also know this one as the tragic helicopter accident which killed Kobe Bryant. The pilot had 8,577 hours of total flight time, and he was the chief pilot of the company. So you would count him as an experienced pilot. Yet as he flew into thick fog, according to the NTSB report, he got the "leans". That is he had the illusion that he was ascending while in reality his airplane was banked and turning. Sadly they flow into a hillside and all 9 people aboard died. A tragic case. It is hard to know exactly when the pilot lost all visual cues but according to the report there was about a minute between the pilot reporting to ATC that they are climbing to get over the clouds and them impacting the terrain. Things unfortunately can go sideways very fast in IMC.

inoffensivename 3y ago

Simply put: VFR, Visual Flight Rules, you can see outside, you must stay outside clouds, it's your job to not hit other planes and the ground. You do this primarily by looking out the window. IFR, Instrument Flight Rules, you are in the clouds and can't see outside, it's air traffic control's job to keep you away from other airplanes and the ground. You keep the plane under control by using your instruments only. Looking out the window yields no information. :-)

kqr 3y ago
Is ATC really responsible for terrain separation? I was under the impression they can advise you when your altitude looks odd, but you are still responsible for avoiding terrain by following procedures and sticking to minimum altitudes, etc.
- alistairSH 3y ago
  The pilot is in control. But ATC will provide an altitude they want you to maintain. When you are cleared to land, ATC isn’t doing anything to keep the plane from hitting a building on final approach.
- tass 3y ago
  They will provide “clearances” which avoid terrain - if they ask you (for example) to fly direct to LAX, they need to ensure you are told an altitude to fly which keeps you at or above the minimum for whatever is between you and that waypoint. As the pilot you are required to follow the instruction but ATC aren’t responsible for you not doing so. There are situations where you may inadvertently lose communications, so ATC can’t tell you to climb for some future higher altitude requirement. In this case the pilot needs to climb and fly the minimum for the area they are in or airway they are following.