Have you ever wondered what does the channel numbers on the SBAS approach charts stand for?

When you select a PBN approach, we find WAAS approach type in United States, or EGNOS in Europe, amongst others. Below the approach procedure designator, i.e. RNAV (GPS) Y 04L in KJFK, a WAAS with CH 77519 appears underneath. Just below channel numbers there is a combination of letters and numbers.

If we remember, WAAS is system which augments GPS signal in other to improve GPS position. To do that, a geostationary satellite system broadcast a correction signal to aircraft. In U.S.A is WAAS. Then, it’s not necessary to place any ground station at airports to broadcast this correction signal to correct aircraft GPS position like in GBAS system. But why there is a channel on the approach chart though?

When the system was designed, the channel number was considered as an optional equipment capability which allowed to pilot to use a 5-digit number to select a specific approach instead of using the menu method as we usually do to choose from our navigation database. These numbers correspond to only one type of approach and they’re unique.

Examples of approach charts WAAS (RNP Y 04L de KJFK) y EGNOS (RNP 06 de EHAM).

Below channel numbers, there is a combination of 4 letters and numbers. This is the approach identifier. In conventional radionavaids, when an ILS or VOR is selected, there is Morse code to aurally ident it. In this case, is visually identified to verify the selection and extraction of the correct approach chart from the navigation database. The first letter corresponds to augmentation system used: W for WAAS or E or EGNOS. The next two numbers are used for runway designator. When there are parallel runways, lest say LEFT, CENTER or RIGHT, letter A, B or C are added at the end. So, in KJFK, for the approach RNAV (GPS) Y 04L, our approach ident will be W04A.

The Jet Stream

The Jet Stream
Have you ever wondered why is it faster to fly from America to Europe than the other way around? The answer is the Jet stream. This ‘river’ of air flowing through the Earth plays a big role in aviation. Airlines have learned how to take advantage of it and plan their flights accordingly.


The discovery of the Jet Stream is often attributed to Wasaburo Ooishi, a Japanese meteorologist. Back in 1923, he observed that strong winds aloft would deviate atmospheric balloons as they gained altitude. By tracking their position, he was able to determine the wind speed. Although it was only a prediction, he was able to record a trend over the years and determined that these winds followed a pattern. His observations remained mostly unnoticed as he published them in Esperanto.

During World War II, Ooishi’s observations allowed Japan to launch “Operation Fu-go”. Using his prediction on winds aloft, the Japanese launched nearly 10,000 hydrogen balloons carrying bombs over the Pacific Ocean to America. Predictions of 190 knots (350 km/h) in wind speed (between 30,000 and 38,000 feet) would carry the balloons to the United States west coast in 3 days. His predictions turned out to be inaccurate and only some balloons arrived and didn’t cause the intended effect.

Balloons loaded with bombs. Photo:
Balloons loaded with bombs. Photo:

American aviator Wiley Post is also attributed the discovery of the Jet Stream. Post achieved the first around-the-world solo flight in 1931, developed the pressure suit and explored the limits of high- altitude flying. In 1935, while flying at 30,000 feet in his supercharged Lockheed 5C Vega “Winnie Mae”, he experienced speeds up to 340 miles per hour. Flying in the Jet Stream he was able to cover 2,035 miles between Burbank, California and Cleveland, Ohio in 7 hours and 19 minutes, proving the benefits of high-altitude flights. The same distance, at sea level, would have taken 12 hours and 42 minutes.

Wiley Post en su "Winnie Mae"
Wiley Post and his Lockheed 5C Vega “Winnie Mae”. Photo: Hulton Archive


The air acts like a fluid, just like water. And so, it flows and it is affected by external forces, modifying its behavior and shaping its patterns.

On earth, due to the differential heating along its latitude, the vertical development of the atmosphere changes. Close to the Equator the air is warmer, so it ascends creating an area of low pressure near the surface. The surrounding air tends to fill in this ‘gap’, so it flows from the higher pressure area to the lower. The ‘gap’ created by the air moving to the low pressure area at surface, creates a sinking motion for the air that is up at the Tropopause. Thus, creating a circulation.

Circulation of the Hadley, Ferrel and Polar cell. Photo: NASA – Wikimedia
Circulation of the Hadley, Ferrel and Polar cell. Photo: NASA – Wikimedia

There are three circulation cells per hemisphere. The Hadley, the Ferrel and the Polar cells. These cells find their top at the Tropopause, the layer at which the air stops rising. Close to the equator, the air is warmer and ascends much higher, elongating the Tropopause further up. The average (it varies during the year) altitude of the tropopause at the equator is 56,000 feet, and 30,000 feet at the poles.

Cross-section of the Cells and its circulation. Photo: Sleske – Wikimedia
Cross-section of the Cells and its circulation. Photo: Sleske – Wikimedia

The Jet Stream originates at the boundary of these cells. Due to Earth’s rotation, the air traveling to this boundary is forced sideways. This is called the Coriolis effect. In the Northern hemisphere, the air traveling North will be forced to flow East. This is why the Jet Stream flows primarily in that direction. The greater the air velocity, the greater the deviation. If the difference in temperature is high between cells, the Jet Stream speed increases, up to 200 Knots (370 Km/h).

The Jet Stream is like a continuous ‘river’ of air, meandering. This is due to the difference in Coriolis effect at different latitudes. These are called Rossby waves, and it’s the reason why we often see Jet Streams that are not directly heading East.

Rossby waves
Rossby waves. Photo: NASA


With all this knowledge, aviation can take advantage of a given atmospheric condition at any time. By using meteorologic and satellite information, we can predict future weather phenomena, winds aloft and more. Airlines use hourly updated information to plan their flight avoiding dangerous weather worldwide.

When dealing with Jet Streams, flight planning departments take into account the position, height, extension and speed of the wind on their planned route. Therefore, anticipating themselves and being able to modify the route to, for example, avoid a strong headwind o a turbulence area associated with it.

Significant Weather Chart of the Atlantic Ocean. Photo:

Pilots also receive weather information in form of SIGWX (Significant Weather Chart) and wind charts. Then, they can also judge the situation, discuss and decide the better course of action. On long haul flights, a route deviation implies a great deal of considerations: Fuel planning can be affected, ETOPS operation may restrict certain deviations, en-route alternate airports may have to be adjusted, the airline may have to consider schedule affectations on connecting flights, etc.


As we have seen the Jet Stream is a fast-flowing stream of air. The air surrounding it is, by comparison, slower or even still. When an aircraft is approaching a Jet Stream area and the wind suddenly increases, it suffers from what is called Windshear. This is a sudden change in relative speed between two adjacent air masses. A change in wind speed causes instability within the air mass. As it flies through it, the aircraft is subject to those disturbances, suffering from turbulence. Also, as the Jet Stream flows right next to the border of the Cell, we find a transition between air temperatures, thus changing the density of the air and creating instability as well.

This type of turbulence is not associated with clouds, that’s why it’s called CAT, Clear Air Turbulence. Usually the turbulence is reduced to a mere bumpy road-like feeling. With short and repetitive shaking, this kind of turbulence is unpleasant for passengers rather than dangerous for flight safety. Nevertheless, there have been situations in which moderate and severe turbulence has been encountered as a result of CAT.

Depiction of a cell boundary, Jet Stream and Area of CAT
Depiction of a cell boundary, Jet Stream and Area of CAT

From the flight planning stage, with help of the aforementioned maps & charts, pilots do their best to avoid such areas. CAT areas are marked and their vertical extent also advised. As we can see in the map, the blue dotted line over Sardinia (Italy) represents an area of potential clear air turbulence. In the legend we can see it ranges from FL210 to FL410. We can also see how it is associated with a Jet Stream that is flowing from North to South (Red line) at 120 knots (Every triangle represents 50kt and every line 10kt).

Significant Weather Chart showing the Jet Stream and associated CAT areas. Photo:
Significant Weather Chart showing the Jet Stream and associated CAT areas. Photo:

When an aircraft is subject to moderate and severe turbulence, the pilots shall report it to the ATC —Air Traffic Control— to help other traffic in the surrounding area and raise awareness of potential hazardous areas. A simple change of Flight Level (Altitude) shall suffice to get out of the turbulent area. Often times, pilots ask the ATC for an altitude change to avoid the uncomfortable shaking.


As a little example of the big influence the Jet Stream can have on a given flight, we are going to take a look at a flight from Los Angeles to Tokyo-Haneda, and how we can take advantage of our knowledge.

We can see that the Jet Stream, the same that instigated the Japanese balloon project, flows along the Pacific Ocean. If we were to follow the standard routing, we would find ourselves right in the middle of the Jet Stream. Let’s take a look at the effect of it.

When flying through the Jet Stream, we are experiencing a sustained headwind of up to 120kt along he whole route. This would result in a flight time of 12 hours and 45 minutes to cover 4835 Nautical Miles, and an estimated fuel burn of 94,800 Kg of fuel. Allowing for contingency, final reserve and alternate fuel we would need roughly 108,000 Kg of fuel on departure.

Conversely, if we decide to deviate further North, even though we will fly a longer route (123 Nautical Miles longer) we will avoid the Jet Stream and the effects are very noticeable. Let’s see:

Flying the Northern route we would fly a distance of 4958 Nautical Miles, it would take only 11 hours and 25 minutes. 1 hour and 20 minutes and nearly 10 tones of fuel less. This represents a massive time and fuel cut, even when flying a longer route. Of course, this is a perfect example, some days the difference would be less. But, all in all, it means millions of dollars in savings when thousands of flights are scheduled on a yearly basis. This is how important is to have an effective operations & flight planning team supporting the flight operation.


Aviation is a complex, ever-changing business. Crew schedules, route network, customer service or staff management. Every aspect of it is subject to sudden changes and continuous adjustment. Airlines sometimes find it difficult to strive in this ultra-competitive world. Mergers, acquisitions and bankruptcies are no strangers to many airlines. We, the people behind this circus, are sometimes caught in the middle of it all.

This is a tale of a pilot’s last flight for an airline.

It hasn’t been an easy summer. Rumours in the office, cockpit talks, hints on the news… We all know something is cooking. Some colleagues are already searching for a way out, others keep the faith and will stay. During this week my schedule has changed several times. The airline is adjusting and re-adjusting the flights, some aircrafts have been impounded by their owner, the lessor. Others are still on maintenance. It looks bad, but we’ll keep on fighting until the end.

I check my roster and my flight has been changed. I will fly to Tirana, stay the night and come back in the morning. As I drive to the airport, I can’t help but think it can be the last time. I’m going to enjoy this flight like it’s the last. I will try to remember every little detail and make the best out of it. When I make it to the office, the captain is nowhere to be seen. Our aircraft is late by more than an hour and he will probably show up right before it lands. I take the flight briefing folder and start to prepare the flight. The office is quiet, nobody dares to speak more than the necessary, everyone suspects we won’t be around much longer. Finally, the captain arrives and, we brief the flight together. It’s looks like a smooth ride over the Balkans on our way to Albania. We check the technical status of the aircraft and decide how much fuel we will take. It looks like the flight is further delayed, so the captain decides we won’t have time to go to the hotel in Tirana. We will stay in the aircraft, as we will have a little longer than two hours until we will have to come back to Ljubljana.


We make our way to the terminal, pass the security control and walk to the aircraft. The apron is quiet, we can see three of our airplanes grounded, sealed. It’s sad we won’t see them flying anymore. We agree he will fly the first leg and I will fly the way back tomorrow morning. Finally, we arrive to our Bombardier CRJ-900. S5-AFA has only been with us for 2 years. It came from Air Nostrum, where it was registered as EC-JNB. We open the doors and I start with the initial checks.

Milky way seen from the first officer seat.

One hour later, we are cruising at FL350. A moonless night brings us wonderful views of the milky way. The purser brings the dinner to the flight deck. I’m not hungry, thoughts race through my mind, I feel uneasy. Nevertheless, this might be the last dinner onboard, so I decide to eat. The flight progresses as usual. We land in Tirana and passengers disembark the plane. It’s 1:30 AM and the captain is powering down the aircraft. Meanwhile, I close the door and set the alarm.

Wake up call. The screen of my phone illuminates the passenger cabin, pitch-black, it’s 4 AM. Swollen face, red eyes, better make some coffee. I pick up the ATIS, prepare the route and calculate the performances, as the passengers start boarding the plane. They probably have no idea of what’s going to happen with the airline and some of them might not be able to come back home after their holidays. Captain asks for the checklist and we start up the engines. “ADRIA727, wind is 020 at 2 knots, runway 35 cleared for take-off”. AFA starts rolling, illuminating the runway as speed increases. “V1, rotate” and I gently pull the yoke to lift up the nose. The aircraft leaves the asphalt slowly and starts climbing into the dark of the night.

It’s 5:30 and the stars are disappearing in favour of a dark blue twilight. The weather is perfect in Ljubljana and we will be the first inbound flight this morning. One of the cabin crew brings coffee. You can’t say no to a cup of coffee with the best views in the world.

Sunrise over Zagreb, Croatia.

As we start our descent, the sun rises over the Balkan skies, calm as ever. We can’t talk to each other, gutted.

Gear down”, we feel this could be our last landing in Ljubljana.

Adria 727, Cleared to land runway 30, wind calm”.

50, 40, 30 – Thrust idle – 20, 10 – Flare…” And we kiss the runway for the last time.

A smooth approach and landing put an end to it. As always, we bring our passengers home, safely, but this time, it feels different. As I step out of the cockpit, I look back and take a last glance at it. Here is where it all started. This airline gave me my first chance, my first job as an airline pilot. I learned how to fly a masterpiece of an aircraft.

Bombardier CRJ900 departing from Ljubljana, Slovenia. (Photo: Adria Airlines)

Two days after Adria Airways ceased operations temporarily. A week later, on September 30th, the airline filed for bankruptcy. This article is dedicated to the people of Adria Airways (1961-2019).

Edgar Domenech Llinares is an airline pilot rated on Bombardier CRJ700 and 900 series. He has been based in Slovenia flying for Adria until vert recently.

He started his career as a cabin crew. He worked for 6 years based in Palma de Mallorca where he managed to get his pilot licenses and ratings.

His passion for aviation drove him to make his dream to come true, learning a lot in the process, and looking forward to learn more in the future.

How racehorses are transported by plane. Very sensitive customers.

In august 2.018, ASL Ireland took a strategic decision of closing freighter company Pan Air. Pan Air which started operations in 1.988, had a highly demanded speciality in their portfolio thanks to their professionality and aircraft used: To transport racehorses onboard.

During spring and summer months, is very characteristic to see in United Kingdom and France racehorses in the weekends. It is a billionaire event thanks to bets and draws many people. Horses are product of best breeds and stables, descendants of champions. It’s value ranges from 5 to 10 million pounds.

Most of Pan Air flights were done from Shannon, in the west Irish coast. Very close is where the most important stables of Europe are located. Due to the highest value of horses and distance from Farnborough, Deauville, Cambridge or Edinburgh, transport by plane worth it.

The airplane.

BAe 146 has been the most accepted model amongst the customers for this specific purpose. It’s a regional four jet engine aircraft manufactured by British Aerospace in the beginning of last decade of twentieth century.

BAe 146-300QT awaits for special passengers. (Photo: José Velasco).

The airplane was designed to land in short runways and, for that purpose has a very characteristic airbrake in its tail cone, a very strong landing gear and very efficient brakes.

It’s also relatively quiet, and its cockpit is wide and very comfortable.

Because it’s a freighter airplane, there are no seats in the cabin. Instead, there are some rails and metal locks to move and fix pallets and freight containers to the floor.

Cargo is loaded into the plane through a big hydraulically operated door on the rear left side of the fuselage. It’s the way horses use to get on the plane as well.  

To adapt the cabin for livestock, up to seven single stables are installed alongside the cabin to make horses as if they were at home.

Stables mounted on cabin of BAe 146.

A pallet of seats is installed in the area between de freight door and the rear part of the airplane. These seats will be designated to all people who travel besides horses: veterinary, loadmaster, and engineer, and grooms.

Because seats are in the rear part of the airplane, horses are facing backwards in order to have visual contact with their grooms.

Very sensitive guests.

Special considerations have to be taken when carrying racehorses onboard of an airplane. The goal is to take them to a race and that is the reason why they are given no substance to make their flight more comfortable. Otherwise, their capabilities could be diminished during the race.

Unknown people are not permitted to get closer in order to avoid they get nervous. Only their personal grooms, veterinaries or, even another animal who travels besides as a companion such as her colt if her/his mother races. Usually, two or three horses are carried and maybe only one or two will race.

Not very luxury but conevenient seats for staff who comes with horses. (Photo: José Velasco).

In addition, to avoid the get nervous, airplane noises are reduced to a minimum. The APU Will be started once the freight door is closed and engines are about to be started as well.

Moreover, getting into the cabin yelling or making noise is absolutely prohibited. For this reason, unless in case of an emergency, the used of PA (Passenger Addressing) through speakers is restricted. All messages take place through interphone with Loadmaster who plays the role as a purser in fact.

During flight, only grooms are authorised to stand-up and stay beside the horses to keep them calmed if necessary.

Horses settle in just 40 minutes. (Photo: José Velasco)

The operation.

Given customers are more sensitive than usual, flight operation has to be very smooth.

Trailers to move horses are more like luxury caravans rather than typical animal transports. Trailers are parked just in front of the airplane’s freight door and their grooms take them into the airplane thanks to a special ramp designed for animals. When this operation is taken place nobody else is allowed to get closer to animals as they could be afraid of a stranger.

Legatissimo boards the airplane with its groom.

One they settle in their respective stable, doors are closed, ramp is disassembled and put into the belly holds of the airplane, and airplane’s freight door is closed.

As we mentioned before, noise could disturb animals. So, APU is started once all doors are closed and just before engine start.

BAe 146 has four jet engine but, its start procedure is quite fast, and there is no need to wait for so long to start taxi.

BAe 146 engine start procedure.

Even this is not a long airplane, is able to turn very close. Because of this, to leave the parking area have to be done with special care and very slowly to avoid high speed turns that could disturb horses. Furthermore, taxi speed is slower than usual and air traffic controllers, who are familiar with this type of operations, advice other airplanes we are carrying “livestock on board”. Basically, to ask for understanding.  

When take-off is about to take place, power is applied progressively and slowly, adjusting take-off power just before a certain speed. To avoid a high speed rotation and a very steep climb, flap position is selected in a very high deflection (30º).

As in take-off, climb gradients do not exceed 1.000 feet per minute in order to avoid steep climbs. This allows animals not to make too much effort with their legs. Flight levels chosen are around 20.000 feet in order to keep the pressurisation system working with a relatively low cabin altitude. Then horses will not suffer any adverse symptoms during race. Besides, in the unlikely event of loss cabin pressure, breathable atmosphere would be reached very soon and there would be no risk for the animals.

When descent and approach is initiated, air traffic control coordination, again is very helpful an essential. Even is contained in our flight plan and controllers are familiar with this kind of flights, we give this information on the radio when we have the first contact on their frequency. Descent is initiated to with time enough to plan it slight.

Approach is flown very smooth. When reducing speed, airplane tends to raise it nose, increasing it angle of attack. To avoid it, we select flaps earlier than usual trying to ease nose up momentum. Moreover, turns to final approach are done with lower angle and at a distance of 15 NM, which is longer than usual.

When landing is about to come, autopilot is disconnected and, as my friend Rafa says, is “when technology ends and art begins”. Overflying runway threshold, tailcone airbrake is deployed smoothly and firmly. Touchdown must be done flat, almost allowing to land with main landing gear and nose landing gear at the same time. Captain’s gold hands are necessary at this time. The Bae 146 is very appreciated after a smooth touchdown and commences to decelerate easily with wing mounted spoilers and its full deployed tailcone airbrake.  

Braking is done manually and progressively, using the full length to stop the airplane.

BAe 146 on it landing roll with its full deplyed airbrakes.

Once parked on stand, a convoy is waiting to take horse to their destination: the race. Before opening freight door and assemble the ramp, engines and APU must be switched off.

When horses are being taken to their new ground transport, number of inquisitive ramp workers are attracted to the plane asking about the animals… Bets move a lot of money.

End of service.

 When this first sector is finished, the whole crew goes to hotel until daily races are over. Then, we’ll start again to take them back to Shannon.

Well done!

Crews are ususally infected with groom’s joy after winning races. Meanwhile, jockey is back on his A319ACJ with horse’s owner.

After a series of flights a bond between crews and people who works with horses is created. There is an empathy with horses and grooms which has been translated into a relationship of more than 25 years. A lot of gratitude has been received thanks to the very good crew’s attitude, high experience and professionality.

For many years Pan Air pilots has shown their value. Even up to their last day. Their commitment has always been showed when situation was very far from being favourable.

I’d like to dedicate this short article to whom they were may colleagues in Pan Air Líneas aéreas for almost a decade. Therefore, serves as a tribute to all staff in the company: administration, maintenance, flight operations, ground operations and, my beloved friends and cockpit colleagues, the pilots. Many names are coming up to my mind, some of them retired some years ago.

All of them in a new professional stage in other airlines but, we’re always will be “Paneros”.

I wish you very happy flights Paneros!

How the ADS – B works. The Future’s technology is already arrived.

The increase in density of air traffic in Europe, United States, and remote areas such as the North Atlantic Ocean, made the necessity to implement Single European Sky programs (SESAR) and NEXTGEN. To achieve this goal, technology plays a vital role. The ADS-B is one of them.

According to stablished critera by every civil aviation administration, as of 2.020, aircrafts must be equipped with ADS-B system. In Australia, pioneers in remote airspace management is already implemented since December 2.009 above FL300. Thanks to this technology they were able to reduce aircraft separations from 30 NM to only 5 NM, increasing airspace capacity significantly. But, What is it? And How does it work?

Principles of working.

ADS-B (Automatic Dependent Surveillance – Broadcast), is a surveillance system which will replace information already obtained from radars.

ADS-B Schematics.

This new system allows navigation systems onboard of an aircraft to obtain its position from GPS signals. Signals are joint together with other flight data gathered from other aircraft’s systems and broadcasted. Signal broadcasted is received by ground stations, inflight stations or satellite’s receivers and represented on a screen.

ADS-B Definition.

Nowadays, to be able to supply air traffic control with radar, air traffic controllers have one o more radar stations on ground to provide aircraft’s position. This information is obtained from radar echoes PSR (Primary Surveillance Radar), or exchanging information between aircraft and ground station, thanks to the transponder. This is known as SSR (Secondary Surveillance Radar). Between the two systems, SSR is the most accurate with MODE S transponder.

System and capacity.

The ADS-B has two basic capacities known as “OUT” and “IN”.

ADS – B “OUT” defines its capacity to broadcast ADS – B information. As an example of what kind of information broadcasts, the A330 with “OUT” capacity sends out the next information automatically and in a continuously manner:

  • Latitude and longitude, Horizontal Integrity Limit (HIL), the difference between barometric altitude and geometric altitude and ground speed (GS). All obtained from GPS signal;
  • Barometric altitude is obtained from ADIRS;
  • Track and vertical speed given by IR’s;
  • The ATC flight number introduced in the preflight check is given by FMS;
  • Emergency status; and
  • Selected altitude and heading, and barometric pressure (QNH/QNE) from the FCU.

This last function allows ATC, if they are equipped with proper system, to see on their screens their clearance and what pilot selected on the same radar tag. Very similar to what it happens with MODE S “enhanced” which uses “Down – link of Airborne Parameters” (DAP). This is what happens in airports such as London Heathrow. But this is another story…

On the other hand, ADS – B “IN”, defines its capacity to receive information from other ADS – B “OUT” stations which broadcast information.

Sounds pretty obvious that an aircraft equipped with both functions will be able to broadcast and to receive ADS – B information, to and from other ADS – B stations.

For an aircraft to able to be equipped with ADS – B technology, is necessary to have datalink equipment in VHF band. To do that, aircrafts use mainly two different equipments: 1.090ES and UAT978.

The UAT978 (Universal ADS Transceiver) is an equipment only used in United States below 18.000 feet. Created for general aviation, if it’s equipped with “IN” capacity, will be able to receive weather information free of charge. However, the rest of the world Will be using 1.090ES complying with ICAO requirements, what in fact has higher data transmission capacity.

But, What is 1.090ES all about? Basically, is a mode S transponder modification, currently on board of aircrafts. As the mode S transponder does, transmits on 1.090 Mhz., broadcasting information instead of waiting for the interrogation from a SSR station. This transponder has a group of extra capacities added to mode S, that the reason for its name: “Extended Squitter”.

Besides, because it’s working on the same frequency, it’s able to comply with airspaces where SSR radar service is provided and with ADS at the same time.


Regarding all conventional radar information which air traffic controller receives, ADS – B is more reliable. All data is sent directly from the aircraft’s navigation equipment.

There is other factor which affects service which is the transmission speed. Nowadays, secondary surveillance radars use interrogation/response of onboard transponders to obtain data information from aircrafts. Let’s say for a moment and aircraft flying under radar coverage equipped with transponder. The SSR antenna begins with an interrogation on 1.030 Mhz. and aircraft through its transponder will response on 1.090 Mhz. with information asked. Once this information is received on ground, is presented to air traffic controller’s screen. To the contrary, ADS – B broadcast twice per second automatically without the necessity to be interrogated by any other equipment. An ADS – B “IN” antenna receiver is only needed.

With ADS – B, all radar antennas could be easily replaced by ADS – B receivers, simpler to install, easy to maintain, more energy efficient, and in the end, cheaper.


If I explained it correctly until now, maybe you were able to guess other advantages or capacities this technology has.

If we add an ADS – B receiver antenna to an aircraft, we would give it ADS – B “IN” capacity. We only would need a way to represent this information in the cockpit: CDTI (Cockpit Display of Traffic Information).

All this will be translated into being represented on places we’re all familiar with, such as TCAS screen, on a MFDU (Multifunction Display Unit), or on a ND (Navigation Display). We would be able to see on one of these screens onboard of our aircraft the same information as the air traffic controllers on their radar screens. There is no doubt how this increases pilot’s situational awareness in highly congested airspaces.

As we mentioned before, he appearance of ADS – B has brought about some new applications: TIS – B (Traffic Information Service) and FIS – B (Flight Information Service).

TIS – B allows information regarding aircrafts with transponder but not ADS – B equipped, flying under radar coverage, to be broadcasted by ADS – B “OUT” stations. This information is received by ADS – B “IN” equipped aircrafts being able to see on their screens onboard other aircrafts around them which are not equipped with ADS – B.

FIS – B allows aircrafts equipped with ADS – B “IN” to receive weather information, ATIS, or NOTAM from ADS – B “OUT” ground stations. This type of service is well known as FIS – B.

New Procedures stablished on NAT – HLA oceanic airspace.

Of course, ADS – B is a very substantial improvement in air traffic control. The ITP (In Trail Procedure), allows aircraft to choose optimum flight levels without being “blocked” by other aircraft flying at a distance with no radar further than “ITP Distance”.

This is, if an airplane wish to climb or descend crossing other airplane’s flight level, and both are ADS – B (“IN” & “OUT”) equipped, sending the request via CPDLC to ATC, it will show  distance from other aircraft, their flight level and callsigns before being sent to ATC on CPDLC’s screen.

Thanks to ADS – B, ATC will receive more accurate information and will have a total picture of airplanes instantly with no ADS – B equipped and ADS – B airplanes. So, it will be easier for ATC to see if they have separation enough to give the clearance for level change request.

Near and future developments.

On the other hand, over remote areas and over oceans, receiver antennas on ground is not possible or feasible. Because of that, for some time companies have been working on a low altitude satellite constellation able to receive ADS – B signals from aircrafts.

This constellation called Iridium is made of 66 active nanosatellites and 9 as spare. They are in an orbit just at 785 km from earth’s surface, being able to receive ADS – B signal and send it to ATS centres. It’s expected to be fully operational in the end of 2.018.

Curiously, and to mention flight MH370 disappearance, the company FlightAware has signed an agreement with Aireon (Owner of Iridium Constellation) to supply airlines with a fleet management and tracking capabilities based on this system. This is the solution to ICAO’s system called GADS (Global Aeronautical Safety System) to continuously monitor aircraft’s position.

In Europe, comparing to United States, there are no immediate plans of integrating ADS – B position to ATC’s system in all regions, and to provide ATC service. That’s the reason why Iridium is fastest solution. In Italy, for example, will be implemented.

The implementation of ADS – B is, as you have read, a very remarkable change in what we already knew about surveillance. There is no doubt the reduction on aircraft’s separation in remote areas will be very valuable, especially in HLA airspace in the North Atlantic Ocean, as it happened before in Australia with no effect on safety at all.  

Besides, being able to handle information rapidly and accurately, crews and air traffic controllers will be able to increase their situational awareness which will lead to take decisions easily.

Finally, implementing ADS – B procedures like ITP, will allow an optimization of airspace. Aircrafts will be able to fly closer to their optimum flight level, reducing fuel burn and CO2 emissions.

Articles and news about aviation.

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