For 280 years, Favre-Leuba has been producing iconic timepieces featuring landmark developments in the world of horology, setting new standards in watch design and engineering, and redefining what is technically possible. In 2017, Switzerland’s second-oldest watch brand is once again providing clear proof that ingenuity and unrivaled innovation continue to inspire everything it does. The Bivouac 9000 is a watch that really pushes the boundaries, a watch that quite literally goes above and beyond what other watches are capable of and makes a very clear statement – a watch that achieves something previously thought impossible.

The design team drew their inspiration for this groundbreaking creation, released to celebrate the brand’s 280^th anniversary, from the company’s own history: in 1962, Favre-Leuba launched the world’s first mechanical wristwatch capable of measuring air pressure and altitudes of up to 3,000 meters above sea level. The outstanding reliability and precision of this watch, as well as the fact that it was extremely easy to use and read, quickly made it a permanent featureon the wrists of mountain climbers, pilots, explorers, and every pioneer who achieved great things thanks to their courage and persistence.

A Watch that Goes Above and Beyond

The Bivouac 9000 is a homage to its legendary 1962 namesake, but has been improved and refined to make it capable of coping with the demands that are now placed on a highly functional instrument that is designed to be a reliable companion at extremely high altitudes.

The Bivouac 9000 still measures altitude with the aid of an aneroid barometer, but now does so up to an incredible height of 9,000 meters above sea level. The red central hand indicates the altitude on the bidirectional rotating bezel, which carries a scale divided into 50-meter steps, up to 3,000 meters. One full clockwise rotation of the red central hand thus indicates a climb in altitude of 3,000 meters. During a climb, the small red hand of the subdial located at 3 o’clock continues to turn too, until, after three full rotations of the central hand, it arrives at its final destination of 9,000 meters above sea level. The bezel is held securely in place by a two‑way ratchet mechanism that prevents it from being unintentionally moved to a different position.

The heart of the barometer is an airtight capsule made from a special alloy. The capsule expands when the air pressure drops as the wearer climbs and contracts when the air pressure rises during the descent. The expansion and contraction of the capsule triggers alinear movement, which is then converted into a rotational movement to indicate the altitude. The altitude is made visible by the red hands on the stone-gray dial. The atmospheric air that is required to measure the altitude enters the chamber containing the barometer capsule through athree‑millimeter opening in the case, which is protected by a perforated membrane.

It is not until you consider that the difference between the air pressure at sea level and at the summit of the world’s highest peak does not even amount to one atmosphere (approx. 0.7 bar),that you can begin to guess how intricate the mechanism inside the Bivouac 9000 must be to precisely measure altitudes up to 9,000 meters.

For example, when a mountaineer sets out from the Hörnlihütte base camp at 3,260 meters above sea level to scale the Matterhorn, he first must set the Bivouac 9000 to the correct height: the small red altimeter hand has just passed 3 on the subdial – which is equivalent to 3,000 meters – while the bezel has been adjusted by the wearer so that the red central hand is pointing at 260. During the ascent to the peak, the climber can now use the wristwatch to monitor the constantly rising altitude via the central hand as it slowly turns clockwise during the climb. When the mountaineer reaches the summit cross, the Bivouac 9000 will proudly display an altitude of 4,478 meters above sea level.

The Bivouac 9000 is also capable of displaying any changes in air pressure at the same altitude. The hectopascal (hPa) scale on the subdial located at 3 o’clock displays the current air pressure on a scale ranging from 1,013 to 300 hPa. If the climber sets the watch to the correct height of theMatter­hornbase camp on the evening before the ascent, the small red air-pressure hand opposite the altimeter hand will be pointing to approximately 680 hPa – the average air pressure at this altitude. Should the air pressure drop during the night, the central hand will turn clockwise and the small air-pressure hand will be pointing to a lower value the next morning. This means the ambitious climber is now in an area of low pressure – the weather has worsened. In extreme weather conditions, for example if a storm is approaching, the difference between the actual and average air pressure can be as much as 150 hPa. However, if the central hand has turned anticlockwise and the small air-pressure hand is pointing to a higher value than it was the previous evening, this indicates an area of high pressure with improved weather conditions surrounding the Matterhorn. With its ability to provide such information, the Bivouac 9000 is an important instrument that helps climbers decide whether or not they should attempt the dangerous ascent or postpone it until another day.

Significant Technological Improvements and Refinements

While the Bivouac 9000 is inspired by its 1962 predecessor, it features a number of significant technical improvements and refinements. The most significant of these is the increase in the altitude it is capable of measuring from 3,000 to 9,000 meters. This required the use of innovative materials for the barometer and precise calculations for the height and diameter of the capsule, as well as anewconversion mechanism for the altimeter.

Unlike the 1962 Bivouac, the new version is also watertight. This is because the air inlet in the case, which is required for the barometer, is protected by a fine but tough membrane made from a micro­perforated hydrophobic material. This membrane allows air – but not water or dust particles – to pass through.

In order to fulfill their function, the perforations in the membrane need to be as small as possible while still being large enough to allow air to circulate. The size of the perforations therefore had to be calculated and tested with extreme precision. This guarantees that the altimeter hand reacts instantly to changes in air pressure, even when the ascent or descent occurs rapidly, for example during a helicopter flight. Additional protection is provided in the form of a plate over the membrane held in place by two screws, with only very fine vents in the side to allow the air to circulate. This plate protects the delicate membrane against physical damage caused by hard, sharp objects or sand.

The Constant Pursuit of Innovative Solutions

Together with the altimeter and air-pressure display, the dial also features a power-reserve indicator at 12 o’clock. This gives the wearer plenty of warning when the watch needs to be wound after the movement has been running for around 60 hours. In line with Favre-Leuba’s long tradition of challenging the status quo, of routinely defying convention, of seeking to follow new paths in pursuit of innovative solutions, the mechanism that drives this power-reserve indicator is also anything but standard. It is designed in such a way that it does not affect the height of the movement and carries out its complex task with as few components as possible, which makes it much more reliable. Generally, the lower the amount of components required for a mechanism, the less likely it is to malfunction. For the power-reserve indicator of the Bivouac 9000, the English differential screw system has been modernized, optimized, and adapted to perfectly meet the needs of this watch.

For thosemountaineerswho push themselves beyond their physical and mental limits, it is crucial to be able to quickly check that the Bivouac 9000 is running smoothly. This is made possible by the hand of the small-seconds subdial, precisely ticking away the seconds at 9 o’clock. The wearer can also count down the days until their next adventure using the date display, located in a window at 6 o’clock.

When Perfect Legibility is Key

When designing the Bivouac 9000, Favre-Leuba took inspiration from its own legendary timepieces to create a watch with a modern interpretation of the brand’s characteristic design elements. Ensuring that the dial is perfectly legible in any conditions was key. The style of the dial is mini­malistic – there is nothing unnecessary to distract the view from the important displays. Plenty of room is given to the large subdials for the altimeter and air-pressure display at 3 o’clock and the small-seconds dial at 9 o’clock, and the power-reserve indicator is clearly visible thanks to its contrasting black arc.

The luminous hour and minute hands and rectangular indexes stand out clearly against the discreet and understated stone-gray dial. But the central altimeter hand is clearly the star of the show with its eye-catching deep red color.

The Bivouac 9000 also attracts attention thanks to its impressive size – the especially robust case measures 48 millimeters in diameter. It is constructed from lightweight, hard-wearing, and hypo­allergenic titanium, which makes the watch comfortable to wear despite its size. The bidirectional rotating bezel, which is intuitive to use and features Favre-Leuba’s trademark tetradecagon design, carries an altimeter scale divided into 50-meter steps. The arc extending across the sides of the case from lug to lug like a bridge spanning over time serve to further emphasize the dynamic aesthetics of this exceptional timepieceand is symbolic of the connection with its ancestor. The vintage-look leather strap also makes it a stylish accessory in any setting.

There is no point on earth at which the altitude is too high to be accurately displayed by the Bivouac 9000. No climb is too steep for this watch, no challenge too great. It is a reliable partner in any situation, and one that you certainly would not want to be without.