La seguridad aérea es de interés público y afecta a toda la sociedad (Javier Aguado del Moral)

In times of universal deceit, telling the truth becomes a revolutionary act (George Orwell)

Cuando el sabio señala la luna, el necio se queda mirando el dedo (Confucio)

martes, 24 de abril de 2012


Low Level Wind Shear 


Categories: Weather | Operational Issues 

This article covers the subjects of Wind Shear, Low Level Wind Shear, and Low-level Wind Shear Alert System 


Wind shear is defined as a sudden change of wind velocity and/or direction. 

Windshear may be vertical or horizontal, or a mixture of both types. ICAO defines the vertical and horizontal components of wind shear as follows: 

Vertical wind shear is defined as change of horizontal wind direction and/or speed with height, as would be determined by means of two or more anemometers mounted at different heights on a single mast. 

Horizontal wind shear is defined as change of horizontal wind direction and/or speed with horizontal distance, as would be determined by two or more anemometers mounted at the same height along a runway. 


Low Level Turbulence which may be associated with a frontal surface, with thunderstorms or convective clouds, or with microbursts, is particularly hazardous to aircraft departing or arriving at an aerodrome. Wind shear is usually associated with one of the following weather phenomena: 

• Frontal surfaces; 
• Jet streams; 
• Thunderstorms or convective clouds especially cumulonimbus or towering cumulus; 
• Mountain Waves; 
• Microbursts. 


The main effects of wind shear are: 

• Turbulence; 
• Violent air movement (up- or down-draughts or swirling or rotating air patterns); 
• Sudden increase or reduction of airspeed; 
• Sudden increase or decrease of groundspeed and/or drift. 

Clear Air Turbulence (CAT), which may be very severe, is often associated with jet streams. 

Rotor action or down-drafts in the lee of mountain waves can create difficult flying conditions and may even lead to loss of control. 


Effective defence against wind shear comprises the following components:

Forecasting, recognition and avoidance of wind shear (see below), aided by LLWAS (see below) and airborne avionics equipment; and, 

Correct response to wind shear encountered during the takeoff, initial climb, approach and landing phases of flight. 

Typical Scenarios 

An aircraft on initial climb encounters a microburst with strong down-drafts, which prevent the aircraft from climbing away, even though the pilot immediately recognises the wind shear and takes correct action. 

An aircraft on approach in head-wind conditions encounters horizontal wind shear resulting in a change of wind component to tail-wind; the aircraft touches down late and fast and overshoots the runway. 


Improved forecasting of wind shear; 

Improved training in wind shear recognition, avoidance and recovery;

More widespread use of ground and airborne wind shear warning systems.

Low Level Wind Shear Alert System 

A Low-level Wind Shear Alert System (LLWAS) is a ground-based system for detecting the existence of wind shear close to an aerodrome. 

The system comprises from 6 to 33 anemometers located at various points on the aerodrome surface. Data from the anemometers are fed into a computer which compares the wind speed and direction measured at the different points and provides a warning in the air traffic control tower if a hazardous wind shear is detected. Warnings are runway-specific and are passed to pilots by VHF communication. 

LLWAS was first installed in USA in the 1970s and is in widespread use in that country. LLWAS has never been installed in Europe. LLWAS is gradually being replaced by Terminal Doppler Weather Radar (TDWR). 

Wind Shear Recognition and Avoidance 

Flight Safety Foundation (FSF) Approach-and-landing Accident Reduction (ALAR) Briefing Note 5.4 — Wind Shear points out that "Flight crew awareness and alertness are key factors in the successful application of wind shear avoidance techniques and recovery techniques." 

Whenever wind shear conditions are forecast, or reported by other aircraft, pilots should include discussion of wind shear recognition and response in the takeoff or approach brief. 

Whether or not wind shear conditions are expected, the pilot must be able to recognise quickly when wind shear is affecting the aircraft. He/she may be aided in this by airport based warning systems (e.g. LLWAS) or by onboard equipment, such as Ground Proximity Warning System or Airborne Wind Shear Warning Systems. 

ALAR Briefing Note 5.4 lists the following indications of a suspected wind shear condition: 

• "Indicated airspeed variations in excess of 15 kts, 27.78 km/h, 7.71 m/s; 
• Groundspeed variations (decreasing head wind or increasing tail wind, or a shift from head wind to tail wind); 
• Vertical-speed excursions of 500 fpm or more; 
• Pitch attitude excursions of five degrees or more; 
• Glideslope deviation of one dot or more; 
• Heading variations of 10 degrees or more; and, 
• Unusual autothrottle activity or throttle lever position." 

Wind Shear on Takeoff and Initial Climb 

Horizontal and/or vertical Wind Shear on take off result in sudden loss of airspeed and/or reduction in climb rate, with potentially disastrous consequences. It is vital that such conditions should be quickly recognised if they are encountered, and that pilot response should be immediate and correct. 

Before Departure: 

Flight Safety Foundation (FSF) Approach-and-landing Accident Reduction (ALAR) Briefing Note 5.4 recommends that whenever wind shear conditions are forecast or reported for take off, pilots "should include in their departure briefing the following wind shear awareness items: 

• Assessment of the conditions for a safe takeoff based on: Most recent weather reports and forecasts; Visual observations; and, Crew experience with the airport environment and the prevailing weather conditions; and,
• Consideration to delaying the takeoff until conditions improve."

"If wind shear conditions are expected," the Briefing Note continues, "the crew should:

• Select the most favorable runway, considering the location of the likely wind shear/downburst condition; 
• Select the minimum flaps configuration compatible with takeoff requirements, to maximize climb-gradient capability; 
• Use the weather radar (or the predictive wind shear system, if available) before beginning the takeoff to ensure that the flight path is clear of hazards; • Select maximum takeoff thrust; 
• After selecting the takeoff/go-around (TOGA) mode, select the flight-path-vector display for the monitoring pilot (PM/PNF), as available, to obtain a visual reference of the climb flight path angle; and, 
• Closely monitor the airspeed and airspeed trend during the takeoff roll to detect any evidence of impending wind shear." 

Wind Shear Recovery

The Briefing Note advises that "If wind shear is encountered during the takeoff roll or during initial climb, the following actions should be taken without delay:

• Before V1: The takeoff should be rejected if unacceptable airspeed variations occur (not exceeding the target V1) and if there is sufficient runway remaining to stop the airplane; 

• After V1: Disconnect the autothrottles (A/THR), if available, and maintain or set the throttle levers to maximum takeoff thrust; Rotate normally at Vr; and, Follow the FD pitch command if the FD provides wind shear recovery guidance, or set the required pitch attitude (as recommended in the aircraft operating manual (AOM)/quick reference handbook (QRH));

• During initial climb: Disconnect the A/THR, if available, and maintain or set the throttle levers to maximum takeoff thrust; If the autopilot (AP) is engaged and if the FD provides wind shear recovery guidance, keep the AP engaged; or, Follow the FD pitch command, if the FD provides wind shear recovery guidance; or, Set the required pitch attitude (as recommended in the AOM/QRH); Level the wings to maximize the climb gradient, unless a turn is required for obstacle clearance; Closely monitor the airspeed, airspeed trend and flight-path angle (as available); Allow airspeed to decrease to stick shaker onset (intermittent stick shaker activation) while monitoring the airspeed trend; Do not change the flaps or landing-gear configurations until out of the wind shear condition; and, When out of the wind shear condition, increase airspeed when a positive climb is confirmed, retract the landing gear, flaps and slats, then establish a normal climb profile." 

Wind Shear on the Approach and Landing

Horizontal and/or vertical wind shear during the approach can result in sudden loss of airspeed and apparent loss of power, with potentially disastrous consequences. A sudden change of wind component or drift prior to landing can make the approach unstable at a point where go-around is not possible or would be extremely hazardous. It is vital that such conditions should be quickly recognised if they are encountered, and that pilot response should be immediate and correct.

Descent Briefing

Flight Safety Foundation (FSF) Approach-and-landing Accident Reduction (ALAR) Briefing Note 5.4 recommends that whenever wind shear conditions are forecast or reported approach and landing, the approach briefing should include the following: 

• "Based on the automatic terminal information service (ATIS) broadcast, review and discuss the following items: Runway in use (type of approach); Expected arrival route (standard terminal arrival (STAR) or radar vectors); Prevailing weather; and, Reports of potential low-level wind shear (LLWAS warnings, TDWR data); and, 
• "Discuss the intended use of automation for vertical navigation and lateral navigation as a function of the suspected or forecasted wind shear conditions."

The briefing note contains some valuable recommendations for preparation and flight procedures. The section concerning Recovery during Approach and Landing is reproduced below.

Recovery During Approach and Landing

"If wind shear is encountered during the approach or landing, the following recovery actions should be taken without delay: 

• Select the takeoff/go-around (TOGA) mode and set and maintain maximum go-around thrust; 
• Follow the Flight Director pitch command (if the FD provides wind shear recovery guidance) or set the pitch-attitude target recommended in the AOM/QRH; 
• If the AP is engaged and if the FD provides wind shear recovery guidance, keep the AP engaged; otherwise, disconnect the AP and set and maintain the recommended pitch attitude; 
• Do not change the flap configuration or landing-gear configuration until out of the wind shear; 
• Level the wings to maximize climb gradient, unless a turn is required for obstacle clearance; 
• Allow airspeed to decrease to stick-shaker onset (intermittent stick-shaker activation) while monitoring airspeed trend; 
• Closely monitor airspeed, airspeed trend and flight path angle (if flight-path vector is available and displayed for the PNF); and, 
• When out of the wind shear, retract the landing gear, flaps and slats, then increase the airspeed when a positive climb is confirmed and establish a normal climb profile. 

Reporting Procedure 

If significant wind shear is encountered during the takeoff and initial climb, or on approach and landing, it should be reported to air traffic control immediately. If the effects on aircraft control are exceptional and/or beyond the effects typically encountered, then an appropriate air safety report should be raised after flight completion.

Accident and Incident Reports 

Events on the SKYbrary database which involve turbulence and wind shear, include: 

A320, Bilbao Spain, 2001 (WX AW) (On 7th February 2001, an A320, operated by Iberia, crash landed at Bilbao, Spain after encountering windshear.) 
• B735, vicinity Billund Denmark, 1999 (WX) (On 3rd December 1999, a Maersk Air Boeing 737-500 landed at its diversion airport with low fuel in severe and un-forecast low level turbulence which affected the whole destination area Billund, Denmark.) 
• B735, Denver USA, 2008 (WX HF RE FIRE) (Runway Side Excursion During Attempted Take-off in Strong and Gusty Crosswind Conditions.) 
• DHC2, Squaw Lake Quebec Canada, 2005 (WX LOC HF) (On 1st September 2005, a DHC-2 Beaver, crashed near Squaw Lake, Quebec, Canada, following loss of control in poor weather and moderate to severe turbulence.) 
• MD82, Little Rock USA, 1999 (WX RE FIRE HF) (On 1 June 1999, an MD82 belonging to American Airlines, overran the end of the runway during landing. The captain and 10 passengers were killed.) 

Airports where Low Level Turbulence applies: BGTL (Thule), EGGD (Bristol), EIKY (Kerry Airport), ENBR (Bergen/Flesland), ENDU (Bardufoss), ENEV (Harstad/Narvik/Evenes), ENFL (Florø), FAGM (Johannesburg), FAJS (Johannesburg/O.R. Tambo International), FHAW (Ascension), GCLP (Gran Canaria), GCTS (Tenerife Sur/Reina Sofia), KDEN (Denver), KJRA (West 30th Street Heliport), LEGE (Gerona), LFMN (Nice/Cote d'Azur), LGSA (Chania), LIMJ (Genova/Sestri), LPMA (Madeira/Funchal Airport), LXGB (RAF Gibraltar), TXKF (Bermuda), VHHH (Hong Kong). 

Related articles and further readings were not included but are available in the skybrary article. 

Ilustramos el artículo con una serie de videos. En el primero, del 27 de febrero de 2010, el fuerte viento asociado a una ciclogénesis explosiva que se paseó por el norte de España pone en serios aprietos al piloto durante la aproximación al Aeropuerto de Bilbao.

El segundo se trata de una aproximación al Aeropuerto de Hamburgo.

Y el tercero dos aproximaciones frustradas al Aeropuerto de Gran Canaria. Según indican en los comentarios “Dos aviones tuvieron que abortar el aterrizaje de forma consecutiva por causas desconocidas ... tal vez una mala orden desde la torre, exceso de velocidad o viento cruzado puedan ser las causas"


Aunque el Aeropuerto de Madrid-Barajas no aparece en el listado, como tampoco el de Bilbao, son frecuentes en verano los torbellinos de aire (pequeños torbellinos que se desarrollan cuando una fuerte corriente ascendente convectiva se forma cerca del suelo durante un día caluroso y pueden causar ocasionalmente daños de consideración) de intensidad variable, que unidos al viento de cola con el que despegan y aterrizan los aviones con frecuencia aumentan el riesgo de accidente.

De hecho el 20 de agosto de 2008, el vuelo JK5022 intentó el despegue con viento de cola lo que supone una penalización de peso, que en este caso se sumó al no despliegue de los flaps y los slats. Era un viento de intensidad variable en el cuadrante sur, en un día de verano en el que son comunes las rachas locales de mayor intensidad y los remolinos de polvo o arena.

lunes, 16 de abril de 2012


El activismo vecinal en contra del ruido nocturno de los aviones ha logrado una importante y definitiva victoria en Alemania con la prohibición de las operaciones nocturnas en el Aeropuerto de Frankfurt.

Adjuntamos la nota de prensa distribuida por UECNA (Union Européenne Contra les Nuisances des Avions) informando al respecto.

Press Release 4/4/12

Frankfurt Campaigners win Night Flight Ban

“I suspect this ruling has brought a Heathrow night flight ban a step closer”

The campaigners at Frankfurt Airport have won a night flight ban after the German courts today ruled in their favour (1). Flights will be banned from 11pm until 5am. It is thought the ruling could have implications for night flights at other European airports. Both Charles de Gaulle and Schiphol airports, where flights operate through the night, have been watching the ruling closely.

The German decision could also influence the situation at Heathrow where the Government will begin consulting later this year on plans for a new night flight regime after the current agreement with the airlines runs out in 2014. At present, no night flights are allowed at Heathrow between 11.30pm and about 4.15am but the Government is under pressure to introduce a ban from 11pm until 6am.

John Stewart, Chair of HACAN, which represents residents under the Heathrow flight paths, said: “This is a very significant ruling which could have implications for airports across Europe, including Heathrow, Stansted and Gatwick. Critically, the German court rejected arguments by Lufthanza that its business would be damaged by a night flight ban. This is the same argument that has been made by BAA and British Airways to justify night flights at Heathrow. I suspect this ruling has brought a Heathrow night flight ban a step closer”.

The night ban at Frankfurt is only one of the demands of the German protesters, thousands of whom occupy the airport terminal every Monday night (2). They are objecting about the impact of the 4th runway which was opened in October. The night flight ban will apply to all the airport’s runways.


(1). For the full story:

LEIPZIG/FRANKFURT, Apr. 4, 2012 (Reuters) — A German court on Wednesday ruled in favor of a night flight ban at Frankfurt airport, Europe's third busiest, dealing a blow to German flagship airline Lufthansa and airport operator Fraport.

File photo of a Lufthansa airplane landing at Frankfurt Airport December 9, 2010. REUTERS/Alex Domanski

Lufthansa says it needs night flights at the airport so its cargo operations can compete with fast-growing Gulf airports and has warned the freight unit's future investment plans of up to 1 billion euros ($1.3 billion) rest on the decision.

After the local government said in 2009 it would allow 17 flights between 11 pm and 5am local time from the end of October 2011 on economic grounds, residents under the flight paths took the case to court.
Their complaint was upheld in October by a local court just ahead of the opening of the Fraport operated airport's fourth runway, drawing howls of protest from airlines.

On Wednesday, the judge at a higher court in Leipzig confirmed the ban and said the federal state of Hesse must make a new decision on whether to allow night flights. He cautioned, however, that there was little room for maneuver.

Lufthansa shares fell 2.4 percent while Fraport was down 1.1 percent.

At a hearing last month, the judge had indicated mistakes had been made in the approval process for the new runway, under which a mediator proposed a night flight ban, before the local government unilaterally decided to allow 17 flights.

Since the temporary ban was implemented, regular Monday protests at the airport have also seen up to 5,000 people calling for the ban to be extended by two hours each night and for the new runway to be shut down.

(2). Pictures from the protest this week (Monday 2nd April):

Como se indica en la nota de prensa, los residentes afectados por el ruido nocturno del Aeropuerto de Londres-Heathrow y otros aeropuertos a lo largo y ancho de Europa, han recibido con alivio, entusiasmo y esperanza la decisión de la justicia germana. La Unión Europea debería legislar al respecto a favor de las personas y contemplar una prohibición generalizada de las operaciones nocturnas en los aeropuertos europeos, con la excepción de los casos de necesidad extrema, como pueden ser, por ejemplo, los vuelos especiales para misiones humanitarias.

AENA debería tomar nota y no demorar lo que ocurrirá, esperamos, más temprano que tarde, y es no operar vuelos programados en horario nocturno (de 23:00 a 7:00) en los aeropuertos en los que haya vecinos afectados por el ruido, empezando por el Aeropuerto de Madrid-Barajas.

¡Que actúe el gobierno de España ya!, y no tengan que ser, una vez más, los alemanes, británicos o franceses los que vengan a poner orden en nuestra casa.

lunes, 9 de abril de 2012


Asturias dispone de un aeropuerto (LEAS) situado en una pequeña meseta. El umbral de la pista 29 se encuentra muy cerca de una vaguada lo que provoca fallos ocasionales en el radioaltímetro y complica la operación en condiciones meteorológicas adversas, particularmente cuando hay niebla intensa y la visibilidad en pista se reduce por debajo de los doscientos metros, que es cuando se efectúa la operación de Aproximación ILS en CAT-III.

En el AIP del Aeropuerto de Asturias, en el apartado 20 REGLAMENTACIÓN LOCAL, OPERACIONES ILS DE CATEGORÍA II Y III, establece unas estrictas limitaciones a las operaciones en Categoría III, que de no cumplirse impiden que pueda llevarse a cabo dicha Aproximación ILS en CAT-III:

Operaciones CAT III limitadas a:

- Los conjuntos aeronave-aviónica que hayan superado con éxito una demostración operacional consistente en la realización de forma satisfactoria de al menos diez aproximaciones simuladas de CAT III a la pista 29 del Aeropuerto de Asturias, en condiciones meteorológicas visuales (VMC).

- Aquellas tripulaciones que hayan recibido entrenamiento específico que incluya la realización de una aproximación ILS CAT III real, en condiciones VMC, a la pista 29 del Aeropuerto de Asturias o en un simulador aprobado al efecto. Adicionalmente, la tripulación habrá recibido una sesión informativa específica previa al vuelo sobre las características de tal aproximación.

- Estas medidas no conducirán, en ningún caso, al incumplimiento de los procedimientos propios de las aeronaves, en lo relativo al despacho del vuelo de acuerdo con la lista de equipo mínimo y a las actuaciones de la tripulación ante avisos y alarmas de los sistemas.

En el apartado 22 PROCEDIMIENTOS DE VUELO se determina lo siguiente:



1.1 La pista 11/29 está autorizada para despegues de visibilidad reducida. La pista 29 está equipada con un ILS CAT III y autorizada para las aproximaciones CAT III.

1.5 La autorización para aterrizar no se dará después de que la aeronave se encuentre a 2 NM del TDZ. Si ello no es posible, se darán instrucciones para que se ejecute la maniobra de aproximación frustrada.

Cuando se efectúen aproximaciones ILS, el permiso para aterrizar sólo se expedirá cuando las áreas sensibles y criticas del ILS (LSA y LCA) estén despejadas.

Se trata de unos requisitos muy estrictos y que ninguna compañía cumple al completo, ya que eso supondría que todos los aviones y tripulaciones han pasado con éxito las pruebas que se especifican.

Según informan El Comercio y Aviación Digital, la casi totalidad de compañías que operan en Asturias realizan aproximaciones ILS CAT III: Air Europa, Air Berlín, EasyJet, Vueling, Orbest, Air Nostrum y Ryanair. La única compañía que rechaza realizar aproximaciones ILS CAT III es Iberia, que sólo autoriza a sus tripulaciones a las aproximaciones ILS CAT II.

Así, el pasado 15 de marzo la niebla obligó a cancelar seis vuelos, dos de Air France, uno de salida y otro de llegada, y cuatro de Iberia con Madrid. Sin embargo los vuelos de Vueling y Air Europa operaron sin nungún aparente problema.

El sistema, implantado en 2003, fue reactivado en marzo del año pasado, después de haber sido sometido a diferentes revisiones y mejoras, tras las protestas de los pilotos de Iberia y Spanair. La vaguada de Santa María del Mar, ubicada en la antesala del umbral de la pista 29 y con una profundidad de hasta 300 metros, daba lecturas erróneas en el altímetro de las aeronaves, por lo que ambas compañías rechazaron utilizar el sistema asturiano. La aproximación ILS CAT III permite al piloto descender, con nula visibilidad, hasta 30 metros sobre el umbral de la pista 29, para decidir si aterriza. Iberia y Spanair mantenían que esa operación era abortada automáticamente por sus aviones, tras detectar la vaguada. Esa negativa se mantuvo en vigor hasta el año pasado, momento en el que AENA, después de celebrar reuniones con los responsables de todas las aerolíneas, reactivó la máxima categoría del ILS, la III. Además el gestor aeroportuario invirtió diez millones de euros en un ILS que dispone de elementos únicos en el país.

Tras una decisión que puede calificarse de política, el apoyo de Ryanair al ILS asturiano evitará que la niebla se convierta en la condena del corredor madrileño, ahora operado sólo por Iberia. Desde el pasado día 3, la aerolínea irlandesa ofrece dos conexiones diarias con el Aeropuerto de Madrid-Barajas, así como otras dos con Barcelona.

En una controversia en la que todos opinan y actúan a su entender, AENA, medios de comunicación, políticos autonómicos, empresarios a través de la Cámara de Comercio de Asturias, compañías aéreas, usuarios, etc., sólo Iberia está actuando con criterio técnico y aplicando con la exigencia debida las condiciones de seguridad operativa publicadas en el AIP.

Entre todos esos opinantes y actuantes no está la AESA con su Servicio de Inspección del Estado, el único que tiene potestad y autoridad para dictaminar si el ILS CAT-III está en vigor, si la tripulación, comandante y copiloto están capacitados para la CAT-III, y si la aeronave está certificada para ILS CAT III. En resumen, si la tripulación y la aeronave cumplen con los requisitos locales establecidos a tal efecto para la Aproximación ILS en CAT-III en el aeropuerto de Asturias.

Hoy por hoy, a Asturias sólo es seguro volar con Iberia, que es la única que cumple lo publicado en el AIP.

Desde Las mentiras de Barajas felicitamos a Iberia por el celo con el que opera en el Aeropuerto de Asturias, y le pedimos que lo haga extensivo al Aeropuerto de Madrid-Barajas. Son muchos los pilotos y controladores que nos han reconocido, en privado, que la operación en el Aeropuerto de Madrid-Barajas no es segura y que tenemos la razón en nuestras denuncias, pero que no se atreven a hacer nada por el temor a perder su puesto de trabajo. ¿Dónde están la AESA y su desmantelado Servicio de Inspección del Estado?