Category Archives: Miscellaneous

Flying across the Andes. Mountain wave.

In the afternoon of April 13 of 1.918, Luis Cenobio Candelaria, an Argentinian pilot achieved the milestone of flying over the Andes for the very first time. With his wooden made monoplane Morane Saulnier Parasol, mounting an 80 HP piston engine, had to face strong winds. At that time, the results of these winds could cause on an aircraft flying over the Andes were unknown. Mountain wave is the result of these winds.  

Year 2.019. Flight Madrid – Santiago de Chile.

We are in the briefing area in order to prepare our flight from Madrid to Santiago de Chile. Our airplane is an A340-600X and we have an expected take of weight close to 373 tonnes. Quite different to Candelaria’s Morane. During briefing, Captain makes a special question which is not made in other flights: “How is it over the Andes?”

The Andes is very large mountain range which extends along South American continent. On the occidental side of the continent besides Pacific Ocean. It’s 8.500 km long with an average altitude between 3.000 and 4.000 metres above sea level. The Aconcagua is the highest peak with nearly 7.000 metres. This big natural wall causes very often turbulences, severe in certain occasions due to a phenomenon called Mountain wave. Specially in the area between Chile and Argentina. Let’s see what’s the mountain wave is and how to prevent it.

Today looks quite smooth. Wind, temperature, pressure difference… But, let’s go back the beginning. Why is this data necessary? What is the mountain wave? Why should we worry about?

Mountain wave.

Mountain wave are great air oscillations on the leeward side of a high elevation as a result of horizontal air mass movement disturbance over the high terrain elevation. To make a picture of the size of this phenomenon, these disturbances can reach hundreds of kilometres horizontally and to reach tropopause vertically. Mountain wave is associated with turbulence, from light to severe. In other words, when winds blow over an elevation creates oscillations on the other side of the elevation. When oscillations are larger, break off and create areas of turbulence. That’s is the reason why we should know how to prevent it.

Horizonatl and vertical wave movement.

Some factors are necessary for a mountain wave to exists. Already mentioned before, it’s the most contributor factor of all, the existence of perpendicular wind to the mountain range. Depending on size of the elevation, from 15 to 25 knots is sufficient.

It’s also necessary a certain atmospheric stability. Stability forces the air to climb on the windward side of the mountain and it’s also forced to descend on the leeward side. Because of its stability, when it’s “pushed” downward creates a wave on its way. If this air reaches a certain speed, it can break away from the up and down air waves having as result the “rotors”.

Rotors are kind of circular air movement which are the main cause of severe and extreme turbulence. A very famous case was when a B52 of U.S. Air Force was caught close to the Rocky Mountains, in the area of Kansas and lost its vertical stabiliser. Miraculously, they achieved an emergency landing with no further consequences.  

B-52 accidented in 1.964. (Picture: Wikipedia)

Visible signs.

Mountain wave is not always visible. If humidity is enough, clear signs of mountain wave like clouds, makes this possible. When there isn’t, there are diagram to prevent it like Graphic of Harrison in the Andes, so the turbulence could be foreseen.

In first case, when analysing wind chart in different levels, it’s easy to see if there is a perpendicular wind to a mountain range and its intensity, so we can expect some turbulence. If the wind speed it’s moderate and there is enough atmosphere stability, the clouds shape “stylizes”, turning into the well known as lenticular clouds. It’s very usual to find temperature inversion in this area. In fact, we can see sometimes some stationary clouds on top of the others due to different wind layers. These are a very representative type of clouds, and they’re located on the crest of waves. They can reach 9 kilometres high easily.

In some occasions, on the windward side the air is forced to climb the slope of the mountains which condenses, creating cloudiness up to the crest. Nimbostratus and cumulonimbus are the most typical type of clouds, covering totally or partially the lenticular clouds in the lower layers. It’s likely to find icing accretion at these levels before reaching to leeside.

Once on the leeside, the air is forced downward the slope and clouds dispel, creating the Föehn wall or cloud-cascade. However, in the upside of the air wave, a little further away from the mountain, air condenses again creating little cumulus or cirrus type clouds. As mentioned before, if wind is strong enough wave brakes away from the rest of waves and creates rotors clouds. This rotor cloud looks like a twisting movement cloud, causing sensation of circular movement by appearing and disappearing. This type of cloud is Cirrus and, you’d better keep away from them, sinking air prevails over lifts.

Typical Coluds disposition when mountain wave.

Amongst documented accidents due to this phenomenon, took place in Spain in 1.953. A Bristol 170 Freighter Mk21 (EC-AEG) of Spanish airline Aviaco was flying from Bilbao and Madrid when they encountered mountain wave and crashed. In an aviation meteorology book, authors Manuel Ledesma and Gabriel Baleriola, published a letter fragment written by Captain Cañete about weather conditions found flying before, and during accident. Captain describes in great details all weather phenomenon found, relating to mountain wave concepts clearly with no doubts at all.

The Andes mountain range.

After Himalaya, Andes have the highest peaks in the world. To fly over them is a daily challenge.

To fly over Andes to/from Santiago de Chile from the Argentinian side is the most difficult one because all mentioned factors affecting are more significant, specially between Mendoza and Santiago. In fact, Aconcagua, the highest peak is in this area. Prevailing winds, coming from west blow on Andes perpendicularly and increases probability of turbulence.

Due to these local peculiarities, some studies helped to develop procedures to anticipate and to avoid mountain wave. Graphic of Harrison is one of them.

This is a graphic used to obtain a reference of turbulence intensity comparing the pressure difference (abscissa axis) between two sides of mountain range, Santiago de Chile and Mendoza, and wind at 18.000 feet (ordinate axis) in Juan Fernández archipelago located 450 NM west of Santiago de Chile. This is, the greater pressure exists on the leeward side, and the lower in windward side, it’s likely to find mountain wave. Besides this, the stronger wind will increase turbulence factor. The result, obtained combining two previous factors in the graphic, gives three different colours areas. Each colour means an expected different turbulence intensity.

Harrison graphic.

Another way, quicker but less accurate, to determine turbulence, is to compare temperatures and QNH (barometric pressure) between Santiago de Chile and Mendoza. If there was a difference of 5º C or more, higher in Mendoza than in Santiago, or if barometric pressure would be higher in between 8 to 12 hPa in Santiago than in Mendoza, we would have a higher probability to find turbulence. It’s more simple and quicker.

As a summary, studies which gave birth the Graphic of Harrison, there are some factor which when concur at the same time raise probability of turbulence in Andes:

  • Wind direction at FL180 in between 280º and 320º;
  • QNH higher in Mendoza than in Santiago;
  • Cold occlusion in Juan Fernández archipelago. Specially in austral winter;
  • Lower temperature in Santiago than in Mendoza.

There is no doubt a pilot reports are necessary and, in this case is part of the procedure when overflying certain waypoints. When overflying from east to west, a full report to Chilean ATC is given with next information: Flight level, sport wind, temperature and level of turbulence found. This data is gathered to make predictive reports of mountain wave. Airplanes are, sometimes, mobile meteorology stations capable of giving very useful atmospheric data.

There are four main routes to fly over the Andes. The highest probability to find severe turbulence is in the area of waypoint UMKAL, south of Aconcagua. In this case, the better option is to divert south, where the terrain is lower, overflying waypoint ANKON. Other waypoints are MIBAS and ASIMO, north of UMKAL, where conditions are likely to be more favourable.

If the route comes from north, it’s more convenient to overfly the Andes a little more up north instead to fly south to ANKON. Flying parallel to Andes on the “bad” sector would expose your aircraft to turbulence associated with mountain wave.

Alternative routes.

How to avoid turbulence?

In the previous point, we mentioned mountain wave created in Andes between Mendoza and Santiago de Chile. However, there are plenty of mountain waves around the world in bigger or lesser scale.

If there would have been reported moderate to severe turbulence, or just some of the previous mentioned visual signs would have been sighted, to scape is a very healthy procedure. Turn 180º or choose an alternate route are the best solutions ever.

By the contrary, if you’re surprised by turbulence, or after a risk analysis you have decided to continue, speed will be your best friend. To keep turbulence speed according to your airplane flight manual, is the best safeguard to keep the structural integrity to high loads caused by turbulence.

Altitude is your ally. Is mandatory to keep at altitudes above the highest peak of mountains. As we mentioned before, rotor clouds are the most dangerous and found at a lower altitude than crests. However, if altitude is too high, the aircraft could encounter high altitude waves with very dangerous lifts and sinks. It is then recommended to fly at altitudes around 25.000 feet which is the safest zone. Even though, lifts and sinks you’d be flying through, suggest keeping thrust power above flight idle to use it in case was necessary. Some flight manuals recommend to disconnect Autothrust/Autotrottle because in certain circumstances system time reaction is longer than required.

Dangerous areas. (picture: BOM aeronauctics forecast handbook).

In light general aviation, besides precautions that have to be taken when flying in high terrain, in the mountain wave case, there is a rule of thumb which helps to determine the safest distance from the mountain to fly away from mountain wave when flying on the leeward side. This is, the elevation of mountain in feet multiplied by wind speed in knots. For example, if the mountain is 1.000 ft high, and wind speed is 20 kt., 20.000 ft (around 6 km) will be the minimum safest horizontal distance.

Carrying passengers means a special briefing to cabin crew is needed when turbulence from mountain wave is expected. The cabin must be secured in advance to avoid unexpected movement of objects which may cause personal injuries. Explaining to passengers the reason of “fasten seatbelts” sign is crucial. We know, some passengers consider excessive our indications of seatbelts use, but we also know that consequences are very serious.  

Ah! To report ATC is not only necessary but MANDATORY, by the way.

In 2.009, we were flying between cities of Bucharest (Romania) and Sofia (Bulgaria) on a Bae146-200QT. In spite it was a cargo flight, typically flown night, we were flying just after sunrise and we could observe some lenticular clouds scattered over the Balkan Mountains, north of Sofia. During descent we’re having some tailwind and winds at Sofia were westerly. We were just passing 25.000 feet and we complicit gazed each other when we realised flight would be a little bumpy over the mountain range. Automatically we ask ATC to stop descending and to reduce speed to our turbulence’s one… Some moderate jerks later on, gave us the impression we took the correct measures. Manolo and I, after more than a decade later, we still remember what happened. With no further consequences we normally landed minutes later in Sofia, by the way.  

It was not all bad, after all.

Flying over mountains or high terrain is the target of some air sports such as hang-gliders or gliders.

Flying gliders.

The wind which helps to create the mountain waves on the leeward side, is the same wind which creates the right conditions to practice this kind of air sports. Near Santiago de Chile there’s an aerodrome where the gliders take the advantage of the westerly winds when blowing towards the mountain range. In Spain, in Piedrahita, Ages or Fuentemilanos; Larange or Lachens in France; Monte Cucco in Italy, are clear examples where to find this addictive air sports.


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!