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Developed for the French Air ForceThe Zenith El Primero Stratos Flyback Striking 10th

The flight instruments in the cockpit of a fighter jet are subjected to abrupt variations in pressure, intense vibrations and violent accelerations – from 9G to 11G. Thanks to its robust construction, the ZENITH Stratos can withstand it all. As the faithful heir of the Rainbow Flyback model developed for the French Air Force in 1997, the Stratos is equipped with the world’s most accurate automatic chronograph movement – the mythical El Primero – as well as the Striking 10th and Flyback functions.

Accuracy and reliability have been the watchwords of the Manufacture ZENITH since 1865. Very early on, this obsession with accuracy and precision played an important role in aviation and transport. Today, this Manufacture timepiece is becoming established in the fascinating world of military and sporting aviation, where performance and absolute confi dence in one’s team members take center stage. Clear for take-off!

The chronometric instrument of the French Air Force

As a manufacturer of navigational chronometric instruments for civil and military aviation, ZENITH proudly presents its new model: the El Primero Stratos Flyback Striking 10th. The original model that inspired this chronograph was the Rainbow Flyback, which was designed according to a set of specifications prepared by the French Ministry of Defense. Watches designed for the military are required to meet a much higher number of demanding specifi cations than those required for civilian use, and this has led the ZENITH engineers to enhance the accuracy, endurance and reliability of their creations even further. These instruments must continue to function accurately even in extreme conditions, such as violent acceleration, pressure and temperature variations, vibrations and magnetic fields. Aviation undoubtedly represents one of the most challenging environments for watches and on-board instruments. This newest ZENITH watch features an extremely durable casing and a notched, unidirectional rotating bezel with a black, scratch-proof ceramic disk. A telemeter scale has also been placed on the dial flange. The large date indicator at 6 o’clock features an instant-change mechanism. The rounded sapphire crystal is inspired by the shape of an astrodome – the dome located on the fuselage’s dorsal ridge to enable astronavigation.

El Primero Stratos Flyback Striking 10th : an exceptional movement that displays tenths of a second

The Stratos Flyback Striking 10th is equipped with the El Primero caliber. This integrated column-wheel chronograph movement beats at a high frequency and is 25% faster than all other mechanical calibers. The Striking 10th function visibly displays each beat of this exceptional mechanism – every tenth of every second – which represents the smallest division of time measurable by a mechanical caliber thus far.

The Stratos Striking 10th is also equipped with the Flyback function. While flying, routes are calculated based on predetermined destinations and times. Before the Flyback function was invented, wearers were required to press two different buttons three times each in order to stop, reset and restart the chronograph hand. This is too complicated and slow for pilots at the controls of a fighter jet. Ingenious watchmakers thus developed the Flyback function, which stops, resets and restarts the chronograph with one push of a single button. Pilots can thus recalculate a new route instantly, giving them an advantage that is particularly vital when landing according to a time conveyed by the control tower. Only 1,969 copies of this limited-edition model will be produced. This number was chosen to mark the year the El Primero movement was fi rst created.

The three ZENITH colors

The three different colors embellishing the counters are a distinct feature that recalls the first El Primero chronograph launched in 1969. At that time, dark dials in black and midnight-blue were the fashion, with matching counters. To enhance readability, however, ZENITH decided to develop a special three-tone dial. These nuances in tones, laid out in a 3-6-9 confi guration, provided superior readability when combined with hands that had been raised off the dial’s surface. The selection of a darker color for the hours counter emphasized the impressive length of time it recorded, while the lighter color adopted for the seconds counter symbolized the fleeting nature of time. The midnight-blue selected for the minutes counter set the chronograph’s essential measurements midway between the two other shades. These three counter colors were easy to remember and thus facilitated the reading of the chronograph’s indications; this same concept has now been revived on the Stratos Striking 10th (midnight-blue for the 60-second counter at 3 o’clock, anthracite-gray for the 60-minute counter at 6 o’clock and light gray for the small-seconds counter at 9 o’clock).

El Primero Stratos Flyback

The Stratos Flyback comes in four other models: a steel version, a highly resistant black Alchron version, and two different black Alchron and gold versions. Alchron was specifi cally developed for the aeronautical industry and for automobile racing, but this hi-tech alloy is now being used in watchmaking. Its magnetic permeability is 50 times lower than that of steel. This material is also especially resistant to corrosion and boasts very impressive mechanical characteristics. Its Vickers hardness number is 210 HV. Before being integrated into the design of the Stratos, the Alchron was subjected to a battery of tests: its corrosionresistance was tested in saline mists, tropical climates and artifi cial perspiration were simulated, and its impact-resistance was tested with a pendulum striker (a hammer-like steel pendulum fi xed to the end of a swinging arm that drops down and hits the case head-on at full force). It goes without saying that the true goal of these tests was to provide the high-precision El Primero caliber with the best high-strength alloy technology available.

The Manufacture ZENITH : loyal to a visionary concept

ZENITH has remained faithful to the visionary concept of its founder: to ensure that all its timepieces are entirely produced in-house. Each of its watches has been produced from start to fi nish by the Manufacture: over approximately nine months, craftsmen from eighty different trades work on each one in turn to guarantee that each watch benefi ts from expertise that has been handed down and perfected by ZENITH for the last one hundred and fi fty years. The fi ve different ZENITH Stratos models, all hand-crafted, are heirs to the watches and fl ight instruments that have equipped the instrument panels of Europe’s greatest military air fl eets.