Training of pilots and flying servants (Air actualités n° 732 - 2020)

A typical exercice near Niort, a morning in june.

An afternoon in November 2021. According to the base commander (letter dated 21/07/21 to the mayor of Niort):
"The homgeneous spread of the activity on the whole zone volume... is a true leitmotiv" 

Harassing zones for PC-21 (may 2021)

The analysis of PC-21 trajectories, between may 2020 and may 2021, reveals the training sectors for the base. The effective area is only 11 000 km2, less than the 18 000 km2 initially available for the base (see above), or the announced 13 000 km2. Excepted the transit zones around Cognac, a dozain of zones is more intensively exploited, mainly north of Cognac. The littoral is largely unexploited, and ocean ones are almost inexistant (a zone at the height of Hourtin is very rarely used). The inhomogeneous character of impacts if even more impressive when one examines the Grob 120 trajectories, which flight over a limited number of spots. In particular, they heavily impact Angouleme and its south region.

With some 250 flyings days a year, 11 000 flying hours a year and 10 Pilatus planes generally working as pairs, it is easy to compute that each zone is used in average 1h30 per day, quite far from the 40 minutes claimed by the military administration. If 5000 hours are transfered from the Cazaux base without enlarging the working area, this would rise to more than 2 hours a day !

The option to bring together bases can only have deleterious consequences for the impacts of the training exercices. Indeed, with a reduced autonomy of 1300 km / 2h20 flight, the Pilatus PC-21 cannot fly very much away from its base. Assuming that, over these 2h20, 2 x 15 minutes are devoted to reaching and coming back from the training zone, this defines a radius from Cognac to Châtellerault, or even smaller to Poitiers. This is about what is observed north of Cognac. If littoral zones and Bordeaux area are excluded, the conclusion is that there is little possibility to dilute the impact. Decisions made to close bases thus have serious consequences for the population, as they necessarily imply a concentration for the nuisances, that no available range of action can mitigate. They have no other justification than economic (in particular, the gathering of the maintenance made by the private society Babcock on a single spot), with no visible consideration for the population..

Fly over density for Pilatus PC-21 (one year).
The training zone impacts 560 000 inhabitants.

Pilot school : this is only the beginning

With 17 Pilatus PC21 planes, the military pilot scholl has already fully proved its great powers of nuisance. But the army has, for base 709, much bigger ambitions and - but should we be surprised - it did not show any other concern than the economical ones.

So, they will add to the existing planes 8 to 10 others, which will potentially contribute 5000 more flying hours, to the 11000 ones done by the 17 planes. These planes will replace the Alphajet on the Cazaux base, which will be transfered to Cognac. The so-called transition" phase will thus be now be operated in Cognac, using Pilatus PC21. The maintenance of these planes will be provided there by the british supplier Babcock (a 11 years long contract, estimated 500 M€), which is another, economical, motivation for the concentration. While the belgium pilots, which were trained in Cazaux, are now located in the USA, there is a great temptation to train foreign pilots on our territory, while Rafales are sold abroad (Greece, Egypt, India, Quatar...). The Cazaux training zones went from the south of Bordeaux to the Pyrénées. Does the military administration intend to move these now to Poitou-Charentes ?

In such a context, the lack of any prevention scheme, of any dialogue prior to these major changes is distressing. One hesitates, to understand this methodology, between contempt and incompetence. Both are not excluded.

* "Training of foreign pilots by the air army is a strong political and industrial stake. Experienced by the french-belgium trainings and mltiple bilateral actions, Cognac 2016 will naturally be open to several cooperations. The future school will, indeed, be empowered to train pilots for the benefit of our european partners... and also to the one of other nations which would like to benefit of the french knowledge." (headquarters of the air force, 2014).

Increase of trafic from/to Cognac-Chateaubernard (2019-20-21)

The true / false of BA709

What does the "grande muette" tell when she finally speaks ? Following examples shows how the commandment may confuse the issue, regarding technical data which are not supposed being mastered by the population. N.B. The deputy assistant cited here had attended an information visit on the base.

• "Not more than 40 min. on the same district" (commander, april 2020): FALSE We have got multiple testimonies and radar tracks showing that planes or pair of planes could manoeuvre the whole morning and/or the whole afternoon on the same district, sometimes for every day in the week.

• "The activity is spread uniformly" (commander, april 2020): FALSE Cumlated radar tracks at april 2021 show, at odds with this, that the base elaborates training scenarios that repeatedly impact specific zones. Moreover, these zones have now been reduced to 11 000 km2, to be compared with 13 000 km2 initially available, mainly for the benefit of costal areas.

• "There is no impact on tourism. Anyway, there is no activity during august" (a deputy assistant, april 2021): FALSE In 2020, the missions from the school were almost normal. We received multiple testimonies from touristic facilty owners who tell how desperate they are. This assistant must have had in mind the coast fair he is used to.

• "This new propeller plane is not noisier; it just makes a higher-pitched sound" (commander, 2020): FALSE The fact that this plane has a screw propeller does not help concerning its two exhausts turboprop without silencers.When the army chose this plane, the regular data to evaluate noise - the so-called NPD curves - were not available from the manfacturer. None of these curves has ever been produced by the army to justify such sayings. Finally, in dec. 2020 (Charente Libre), the commander concedes that his planes are "noisier". A nice example that the army administration tells the truth only when forced to.

• "Starting recently, we now manoeuver on the ocean" (commander, dec. 2020): MARGINAL The training scenarios elaborated by the base only make use of very rare maritim transits and, very recently, of also very episodic manoeuvres by Hourtin. The overwhelming majority of missions are done over ground. In 2020, only between 1 and 2% of the missions where over sea.

• "One cannot disclose the training spots: that would be too dangerous owing to terrorism" (a deputy assistant, april 2021): RIDICULOUS First, such spots are shown on maps that are sent to individuals who complain about the nuisance. Second, everyone may follow the planes trajectories on the web. Third, it would be much more simple for a terrorist to target a big commercial plane, than these tiny acrobatic Pilatus. And finally, what would be the problem, as the activity is officially spread 'uniformly' ?

• "When they fly at 3000 meters, you do not hear them" (a deputy assistant, april 2021): FALSE We could observe that a PILATUS PC21 manoeuvring 3000 meters ahead, in particular as it makes sharp turns, does produce a heavy sound comparable to a sander on a floor above one's head. At this altitude, depending on weather conditions and manoeuvres, the impact distance is about 10 km. For this largest distance, the impact can be comparable to the one of a loud motorbike in the distance.

• "They dont fly during week-ends": TRUE Not sure, however, this is to spare inhabitants rather than pilots..

Pilatus PC-21: a specific impact

The evaluation of sonic impact relies mostly on two noise figures.
First, the intensity, of course. For the Pilatus PC-21, this overcomes easily 45 dB for 3000-4000 meters altitude at the vertical.
Second, the spectral purity, that is to say the concentration of the noise power in a narrow frequency band. Opposite to white noise, with a uniform repartition of power over frequencies (such as sea shore noise), the frequency concentration of pure noise makes it particularly perceptible and detremental. The following graph shows that the Pilatus PC-21 noise power is highly concentrated on a narrow frenqcy range and some harmonics (here, 250 Hz, 500 Hz, 750 Hz). Thus, this is a high purity noise. This characteristic allows the motor noise to be heard up to 10 km away from the source in the case of tight manoeuvres. A high altitude jet, although it is also perceptible, shows drastically different characteristics: the noise powe is spread uniformly over the range 0-400 Hz.

Compensations for airport annoyances: rural residents disregarded

The Cognac-Chateaubernard airport owns a noise exposure plan, which is mandatory. It is clearly expected a strong impact around the base, particularly along the circular approach tracks ("D" zone). On such zones, this may represent 100 to 200 overflights a day. We note that the legal exposure plan did not incorporate the noisy PC-21 float, so that its accuracy may be questionned.
While regulations do incorporate construction limitations on these zones, as well as legal notice to buyers (and candidates to leave may expected numerous...), financial helps to phonic insulation of homes are limited to the 12 largest airports in France. An airport as Cognac-Chateaubernard cannot benefit from such helps, though the projected trafic (86 000 per year) is only half of the Nice-Cote-d'Azur one. Should one consider this as a another carelessness for rural areas ?