Air Traffic Control Services In Ireland

ATC Tower

 

Air Traffic Services

Air Traffic Services to General Aviation (GA) traffic are provided by the Irish Aviation Authority

The different types of Air Traffic Services available in Ireland are as follows:

  • Air Traffic Control Service (ATC)
  • Flight Information Service (FIS)
  • Alerting Service

Air Traffic Control (ATC)

ATC at an aerodrome is responsible for the seperation and control of aircraft in the air in the vicinity of the aerodrome and all traffic on the ground. All ground movements of aircraft require prior permission from ATC.

ATC may use different radio frequencies for ground movements, local traffic, IFR traffic and for aircraft further away from the aerodrome to avoid frequency congestion. Examples of the radio callsigns for these frequencies are as follows:

  • Cork Approach
  • Cork Ground
  • Cork Tower
  • Cork Radar

If the station you are talking to has a callsign using any of the words “approach”, “ground”, “tower” or “radar”, then you will know that you are talking to an ATC service.

Flight Information Service (FIS)

FIS is provided at some aerodromes which do not have ATC to give information relevant to the safe conduct of flights within the control zone.

The FIS is not permitted to give instructions to aircraft in flight but may give taxi instructions to aircraft on the ground. FIS is not a control service. When FIS is provided, the callsign suffix “Information” is used, e.g. “Dublin Information”. This callsign lets you know that it is a Flight Information Service and not Air Traffic Control.

FIS is not currently used in any aerodrome control zones in Ireland but it is used in uncontrolled airspace. The FIS service provides local information on weather, serviceability of radio navigation aids, aerodrome conditions and other reported traffic.

Air/Ground Radio Station

Some aerodromes provide neither ATC nor FIS. They are normally smaller aerodromes or less busy aerodromes. A lot of these aerodromes have an Air/Ground radio station that allows them to communicate with other aircraft. These radios are normally manned by people without ATC qualifications (if they are manned at all). These stations might only operate at weekends so do not be surprised if you call them and no-one replies. The Air/Ground station cannot give any instructions to aircraft. Only basic information is provided, e.g. wind velocity, active runway, traffic in the circuit etc. The callsign suffix “Radio” is used for these stations, e.g. “Birr Radio”.

Summary

Further information about Air Traffic Control (ATC) services, Flight Information Service (FIS) and all Air Traffic Services in Ireland may be found in the Aeronautical Information Publication (AIP) Ireland. Ask your instructor to show it to you if you have not already seen it. You can also download the AIP from the Irish Aviation Authority’s website. AIP download.


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Frontology

Cold Fronts and Warm Fronts

Introduction

Just today, one of my students asked me to post some information about fronts. Meteorology is such a large subject, it is sometimes difficult to know where to begin learning. For this post, I am going to concentrate on “Frontology” – the study of weather fronts.

As helicopter pilots, we are very aware of what an important role weather plays on the safety and comfort of our flights. It is important that we can interpret weather charts and decipher coded Meteorological Reports (METARs) and Terminal Area Forecasts (TAFs).

Synoptic charts (pressure charts) are one of the most commonly used charts that we use to try and predict the weather. We are going to look at the fronts on these charts in detail.

The Cold Front       

The best way to think of a cold front is to think of it as a parcel of cold, dense air moving along the surface of the earth. As it moves, it undercuts the less dense, warmer air ahead of it and this causes the warmer air to rise. As the air rises, it creates lower pressure and if there is enough moisture in the air, Cumulus (Cu) clouds will form. This type of cloud can produce showery rain but there will be good visibility in between the showers. Cold fronts can move up to two times faster than a warm front and because of this they can produce sharper changes in the weather.

As the cold front passes, the following occurs:

  • A sudden drop in temperature.
  • Atmospheric pressure starts to increase.
  • The wind becomes gusty.
  • Thunderstorms (with sufficient moisture).
  • Cumulonimbus clouds .
  • A drop in dew point temperature.
  • Poor visibility starts to improve.

After the cold front passes, the following occurs:

  • Temperature drops steadily.
  • Atmospheric pressure increases steadily.
  • Wind veers (changes direction clockwise in the northern hemisphere).
  • Rain showers start to clear.
  • Good visibility
  • Falling dew point.

If there is not enough moisture in the air, a cold front may pass without any visible signs as there will not be enough moisture to form clouds.

The Warm Front    

Think of a warm front as a parcel of warm air moving across the surface of the earth. It will have colder, more dense air ahead of it. The warm air is forced over the top of the colder, denser air. This happens at a shallow angle. As a warm front approaches, clouds associated with the front may be seen up to 500km before the front arrives. The first clouds to be seen are the high altitude clouds (Cirrus and Cirrostratus) This is followed by the middle altitude clouds (Altostratus). Close to the front there will be Nimbostratus clouds which produce continuous rain (or snow). When the front passes there is normally a layer of Stratocumulus clouds. As the warm front passes, the following occurs:

  • Sudden temperature rise.
  • Atmospheric pressure levels off.
  • Variable winds.
  • Nimbostratus clouds with stratus and sometimes cumulonimbus clouds
  • Continuous rain, snow or drizzle stops as the front passes.
  • Visibility is poor but improving.
  • Dew point rises steadily.

After the warm front passes, the following occurs:

  • Temperature rises and then levels off.
  • There is a slight rise in atmospheric pressure then a decrease.
  • The wind veers (in the northern hemisphere).
  • Usually no precipitation but sometimes light rain or showers.
  • Clouds clearing to scattered stratus.
  • Visibility is fair in haze.
  • Dew point rises and then remains steady.

The Occluded Front       

An occluded front is formed when the faster moving cold front overtakes the warm front ahead of it. There are two types of occluded front.

  1. Cold Occluded Front. This occurs when the air behind the front is colder than the air ahead of the front.
  2. Warm Occluded front.This occurs when the air behind the front is warmer than the air ahead of the front.

A wide variety of weather may be found along an occluded front. They usually form around mature low pressure systems.

Synoptic Charts

Now that you know what the different types of front are, you are capable of making better decisions during your flights or during your flight planning. You can make reasonable predictions about the kind of weather you are likely to encounter. There are other symbols on the charts and lots more information can be derived. I will cover this in another post One of the Meteorological websites I commonly use to get this information is Propilots.


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The Helicopter Circuit

Helicopter Circuit Pattern

Why Fly a Helicopter Circuit?

Airplanes fly circuits. They fly them a lot and we can understand how this helps the pilots improve their handling of the aircraft.

But most helicopters do not normally do their approaches to a runway. We normally approach directly to where we want to land. So why do we need to do circuits? There are a few very good reasons:

  1. Circuits cover a lot of the flight exercises. E.g. hovering, spot turns, transitions, climbing, climbing turns, straight and level; to name just a few. By flying a circuit, your instructor or examiner can tell just how well you are flying the helicopter and what your weak points are.
  2. By flying circuits, you gain an understanding of the operation of the airport and the circuit and you develop a situational awareness of other aircraft in the vicinity. When you arrive at an airfield for the first time, you will know the procedure to follow and what is expected of you in the circuit.
  3. When you fly circuits, you improve your handling of the aircraft and the accuracy of your flying will improve.
  4. Any confined area you land at will require you to fly a circuit.

How to Fly Helicopter Circuits

Prepare for the circuit. If you are going to be landing at an airport for the first time, then you will need to do a little bit of research.

  • What is the layout of the runways?
  • What radio frequencies will you need?
  • What is the helicopter circuit height?
  • What direction is the circuit?
  • What is the altitude of the airfield?
  • Are there any obstacles that you should be aware of?

All of this information may be found in the Aeronautical Information Publication (AIP) (in Ireland).

Let us assume that you have done all of this and you are going to fly left circuits at your local airfield.

Upwind Leg

Before commencing a transition for the circuit, make sure you complete a clearing turn to ensure that you do not cut in front of another aircraft or climb into the belly of an aircraft. Build up a mental picture of any other aircraft in the area. This includes taxiing aircraft and other aircraft in the circuit. Transition into forward flight. Overcome flapback and translational lift. Establish a steady climb at 60 knots. Check the engine temperatures and pressures during the climb.

Crosswind Leg

When you approach 500 feet above ground level (AGL), check that the aircraft is clear right, clear ahead and clear left. Pick a feature on the ground that is 90 degrees on your left and turn towards it. Continue climbing on the crosswind leg.

When you approach 1000 feet AGL, check that the aircraft is clear right, clear ahead and clear left. Level the aircraft at 1000 feet using the Attitude, Power, Trim method. 70 to 80 knots is a good speed for circuits (depending on the type of helicopter you fly). Pick a feature on the ground that is 90 degrees on your left and turn towards it. You are now on the Downwind leg.

Downwind Leg

You should now be in straight and level flight at 1000 feet AGL and 70 to 80 knots. Perform a “FREDA” check (Fuel, Radio, Engine temperatures and pressures, Direction and Altitude). When you are abeam your landing point, imagine a line projecting from it at 45 degrees. Where this imaginary line intersects your track, this will be your turning point. Check that you are clear right, clear ahead and clear left. Pick a feature on the ground that is 90 degrees on your left and turn towards it. You have now turned onto the base leg.

Base Leg

Once on base leg, lower the collective and make sure you have a positive rate of descent by checking the Vertical Speed Indicator (VSI). The idea is to descend to 500 feet AGL. Don’t worry of you have not reached 500 feet before turning on final. You will have plenty of time to lose the height. Check that you are clear right, clear ahead and clear left. Turn towards the threshold of the runway. You have now turned onto the final leg.

Final Leg

Perform another FREDA check. Slow the aircraft down to 60 knots. If there is a strong wind blowing, increase your speed by the amount of the wind velocity until you are closer to the threshold otherwise it will take a long time to get there. Fly straight and level at 500 feet and 60 knots until you have a good site picture (ask your instructor if you are unsure about what a site picture is). When the site picture is in the correct position on the windscreen, lower the collective and ensure that you have a positive rate of descent. Use the collective. Be firm with it and make sure that the helicopter follows a constant angle to the approach point. At approximately 300 feet, use a little aft cyclic to bring the nose up slightly and start reducing the speed. The idea is that you have a gradual reduction in speed from this point until you come to a hover at the threshold. At 200 feet decide if everything is looking and feeling good on the approach. 200 feet is your commit height. If everything is not right at this point – go around and fly another circuit. At 100 feet, let the site picture begin to move down the windscreen. Keep the helicopter moving forward and aim to come to the hover over your landing point. Anticipate the loss of translational lift and be ready to compensate by raising the collective. As you raise the collective you will need to adjust the pedals to compensate for the change in torque. Come to a steady hover or land. You have now completed a helicopter circuit. As you already know by now, it requires a lot of concentration to do this properly. I always tell my students to never let the helicopter take them where their brain has not been 2 minutes earlier. Plan your helicopter circuits. Think ahead. Anticipate your turning points, your altitude level offs, FREDA checks, radio calls etc. Strive for perfection in the circuit. You will never achieve it but this will certainly improve your confidence and precision in flying the helicopter. I hope this post has been of some value to you and any comments would be appreciated.


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Navigation Diversions

Navigation Diversions

How to Fly Navigation Diversions

A large part of anyone’s helicopter flight training is spent on teaching Navigation. Navigation is an acquired skill and takes practice. During your skills test you will have to carry out a navigation diversion. Navigation diversions can be the most intimidating part of a License Skills Test (LST) but I am going to show you a technique that I use with all of my students and it works extremely well. I will assume that you are capable of doing normal navigation flight planning and can also hold an altitude and heading during flight. During the navigation portion of the LST, your examiner will, at some stage, tell you that he wants you to divert to a different destination. One that you have not planned for. There are a few things you must do before you head of blindly on a rough heading. Before the flight, you will have drawn a LARGE arrow on your chart showing where the wind is coming from and marked the wind speed and direction on this arrow. You will also have calculated the crosswind component for this wind at 30 degree intervals relative to the helicopter and drawn a table on your chart.

Detailed information about navigation can be found in this book: Air Navigation (Air Pilots Manual 03)

  • E.g. 1: If the wind is 15 knots and is on your 12 o’clock, there is no crosswind component and therefore no course correction to make but your ground speed is reduced by 15 knots.
  • E.g. 2: If the wind is 15 knots and is on your 1 o’clock, there is a (1/3 airspeed) 5 kt crosswind component (15 / 3 = 5) and a 5 degree course correction is required. Ground speed is reduced by 10 knots (2/3 airspeed) ((15 / 3) x 2 = 10).
  • E.g. 3: If the wind is 15 knots and is on your 2 o’clock, there is a (2/3 airspeed) 10 kt crosswind component ((15/3) x 2 = 10) and a 10 degree course correction is required. Ground speed is reduced by 5 knots (1/3 airspeed) (15 / 3 = 5).
  • E.g. 4: If the wind is 15 knots and is on your 3 o’clock, there is a (3/3 airspeed) 15 kt crosswind component ((15/3) x 3 = 15) and a 15 degree course correction is required. Ground speed is not affected as there is no head/tail wind.

 

  1. Pick a point on the ground that you can use as a reference point while you do your planning for the diversion. Fly in a wide circle around this point or fly towards this point if it is further away (while you do your navigation diversion planning). Tell your examiner what you are doing.
  2. Draw a rough line on your chart from an easily identifiable point on your chart (close to your position) to the diversion destination. Measure the distance accurately.
  3. Set your pencil on the line and move it (without changing its direction) over a V.O.R. compass rose. Take a not of the heading on the compass rose. This is a magnetic heading so there will be no requirement to take variation into account. (It may help to have a previously drawn V.O.R. with a larger diameter, drawn on your chart).
  4. Now take a note of the wind direction relative to the helicopter using the large arrow you have drawn on your chart. Use the clock code (30 degree intervals).
  5. Refer to the table you made up before your flight (refer to the examples above). From this table you can see what your ground speed and your course correction are. Calculate the time to get to your destination at the new ground speed and tell your examiner what heading you are going to use and what time you are going to arrive at the destination.
  6. Note any features on the chart that may aid your navigation diversion to the destination.

This may sound like a complicated method for teaching navigation diversions but bear in mind that 90% of it is carried out on the ground before the flight and you have actually very little to do during the flight.

For information on how to navigate using radio navigation aids, read Radio Navigation and Instrument Flying: Air Pilot’s Manual (Air Pilot’s Manual Series) (v. 5)

Further information may be found at My Helicopter Training Blog. This method is the simplest that I have ever used for helicopter flight training and it actually works every time when used correctly.


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