How does an airplane find the landing field when it is foggy or very cloudy? Do they have special lights?

Question

How an airplane finds the landing field during heavy fog or clouds: Special lights on the plane? What is a good website that can explain this in detail? Could their methods be used on cars ?

Answer 1

Most aircraft are equipped with instruments that allow the pilot to locate an airfield and conduct what is known as an instrument approach. This requires you have a published landing procedure and use the instruments in your aircraft to follow the procedure. Do that and you'll end up right above the runway.

Answer 2

It's part of what is called an "Instrument Landing System" or ILS for short.

They use radar transmitters on the ground to send out directional (meaning if you receive the signal from a different direction, it will be different), to help position the aircraft in the correct glide path to the runway.

Since the radar is directional, instruments on the aircraft that recieve the signal will be able to tell the pilot where he is in relation to the correct glide path to the runway.

Some are more sophisticated than others and allow landings with lower visibility and vice versa.

In the future, they may use GPS signals instead of radar signals.

Answer 3

GPS is best for cars, unless you're talking about seeing the road in blinding fog. Remember, except when near the ground, knowing where you are to a mile or two is usually good enough for a plane. That's not very good in a car.

For a commercial airliner flying under IFR, they find the landing field itself more or less the same way they find anything. IFR means you can fly through clouds, so you can't see anything out the window. You have to have some way to know where you are going and where you are or that wouldn't work whether landing or not. Techniques include assistance by an air traffic controller using radar (called 'radar vectors') and many forms of gyroscopic and electronic navigation, including GPS.

GPS is taking over en route navigation now. However, the system of VOR airways (virtual 'highways in the sky' laid out by ground-based navigational beacons) is heavily-used, though the FAA has plans to decommission parts of it.

At some point, you'll be within a few miles of the airport and a few thousand feet of the ground. If you can't see the ground, you can't tell where the mountains might be and how far you can descend. At that point, you need to use some form of instrument approach.

There are many different types, but they all includes a basic set of concepts. You follow a precise sequence of steps. These steps tell you when to turn, how far to turn, how much to descend, and so on. At some point, you either find the runway and land, or give up and follow the sequence to climb to a safe altitude on a safe path (called a 'missed approach').

Each approach has a set of weather requirements and equipment requirements. If you don't meet all the requirements to attempt an approach, you don't do it (unless it's an emergency of course). In the United States (and other major ICAO countries), approaches are carefully surveyed and maintained and provide large safety margins. (Sadly, the military has learned that this is not true everywhere.)

Approaches vary in how you tell when you should go to what step of the approach and what kind of information they give you as you do the approach. ILS approaches use specialized transmitters right at the end of the runway. During the final approach phase, an ILS approach gives you a crosshairs that will indicate if you are high, low, to the left, or to the right of the approach path. This is kind of the gold standard, as it's usable to within 200 feet of the ground in most cases and gives you the best information.

Today, ILS is probably the best approach method in bad weather. In the future, precision GPS approaches using WAAS (a system of ground stations and an extra satellite that make GPS more accurate) will probably replace it.

You might think every airport could have a super-accurate GPS approach immediately. But complicated ground surveys are needed to ensure the approach is safe in all phases and to make sure you can safely abort the approach if needed. (Especially in areas with lots of uneven terrain, fast growing trees, and the like.)

Aircraft do have landing lights. They mostly help other aircraft to see you though. If you're close enough to the ground that you can see your landing light bouncing off it, you probably have problems. (Or you're right about to land.)

""Someone else here said that ILS approaches are based on "radar transmitters". That is not correct. ILS signals are in the neighborhood of 109 MHz, well below radar frequencies."" -- Nonsense. Radar refers to a technology, not a particular frequency. ILS is not a form of RADAR only because the signals only travel in one direction and are not timed.

Answer 4

The basic answer to your question is that airplanes can use ground and satellite-based navigation systems to locate the airport. The common feature of these systems is that they enable the pilot to use special instruments to determine the location of the airplane and the runway without being able to see the ground.

There are several systems and each has pros and cons. The ILS system that others have mentioned is very accurate. It provides both horizontal (side-to-side) and vertical (up-and-down) signals. The pilot can center a vertical needle to stay on the horizontal course and center a horizontal needle to stay on the vertical course. With most ILS systems you can fly down to about 200' above the ground (AGL). If you don't see the runway at that point there is a procedure to abort the landing and either go around for another try or go to an alternate airport.

That sounds pretty good but not all airports have ILS equipment. It requires not only special equipment but also continuous monitoring by air traffic control to verify it's working all the time. So you don't normally see an ILS at a non-towered airport.

There is a new version of GPS that lets you fly almost as low as ILS. GPS is satellite-based. The pilot uses the same kind of display to keep the needles centered as he flies down to the runway. GPS has the advantage of being cheaper and easier to set up, so smaller airports can get GPS approaches.

Standard GPS approaches and VOR approaches only provide horizontal navigation signals and are only good down to about 600' AGL so they require better weather than ILS and the new precision GPS approaches.

Pilots can also fly by following directions from the tower. This is called an ASR approach. It's not very efficient because it requires the complete attention of one controller. It's good in an emergency situation but is not commonly used for normal conditions.

Pilots are required to have special training as others have mentioned. Not only do they need to learn how to perform these procedures for flying into airports in the clouds, but they have to learn to ignore the physical sensations they have during flight and act only on what they see the instruments doing. For example, if you transition from level flight to a descent, you can have a feeling like you're tumbling backwards. When coming out of a turn you can have a sensation like you're spinning in your seat. You have to ignore these feelings and do what the instruments tell you.

Someone else here said that ILS approaches are based on "radar transmitters". That is not correct. ILS signals are in the neighborhood of 109 MHz, well below radar frequencies.

Others have compared navigating by GPS in your car to navigating by GPS in an airplane. There is no comparison. For example, next time you're out, program your GPS to give you directions to where you're going, then blindfold yourself and try to drive there. Needless to say you're going to end up in someone's living room. Ground-based GPS units assume you're following roads and they will go out of their way to show you on the roads even if you're out in the middle of a field. Airplane GPS displays show your distance in feet on either side of the line you're trying to follow. So you can look only at the GPS display, not out the window, and fly exactly to the point you're going to.

Back to your question: In heavy fog none of these systems are useful. You need some ground visibility -- around half a mile or so in many cases -- to be able to use a precision instrument approach to an airport.

Lights on the airplane just light up the clouds. We actually turn the lights off when flying in the clouds because they're very distracting, especially at night. You have red, green and white strobe lights on an airplane. When you're in the clouds at night with your nav lights on it's like an acid trip with red green and white flashing light flooding in from all directions.

Answer 5

They use special instruments that show them where they are.  That is why not all pilots may fly in bad weather, they don't know how to read the instruments and/or their planes don't have the instruments.

Answer 6

These days, they have GPS, good to about 10 feet.  Cars have GPS now too.  "Turn right in 100 feet" it says out loud.  Works pretty good, most of the time.

I never had a good idea that wasn't already implemented by someone else already.  When i was seven, i invented the snowmobile.  That winter, my next door neighbor bought one.

Answer 7

Horizontal and vertical electronic guidance.

Answer 8

Have you ever been in a car with a GPS that gives you directions?  That's the basic principle.  The difference is that we have a bunch of instruments that guide us instead of a nice voice saying "turn right in 1 mile".  As you get really close to the runway, there are special "approach lights" that help you transition from flying by an instrument to flying visually down to the runway.  

To learn more, go to wikipedia and search for things like "ILS", "VOR", 'Instrument Approach", etc.

Answer 9

The legal term for the weather you're talking about is Instrument Meteorological Conditions. If an airport is experiencing IMC during the day, the ground lighting is turned on.

To land in IMC, you have to be flying an IFR equipped aircraft, which basically means you have special radios and instruments that will let you pick up signals from the airport. You also have to have an Instrument Rating, which means you have been trained to fly in IMC.

Those signals are called the ILS, or instrument landing system. They provide the pilot the invisible path to the runway, even if the clouds and fog are so thick you cant see the runway at 200 feet above the ground.

The ILS display is basically a set of moving crosshairs that show if you are too far left or right, or too high or low.

There are also ground beacons called VORs, and of course GPS that pilots can use in conjunction with published instrument approaches that will guide him/her to the runway.