Passion for aviation inspires a spectacular timepiece

To call the HM4 a watch is like saying an aircraft carrier is a boat. Of course the HM4—short for Horological Machine No. 4—tells time, but it is far more than a mere timepiece and ultimately reflects the creative genius of its creator, Maximilian Büsser, and his team at MB&F, the Swiss watchmaker.
Priced in the low two-hundred-thousands, the HM4 captured our attention because of its distinct aerospace heritage. A fine watch is, after all, the super-tight tolerances and jewel-like balance of a powerful turbine engine made miniature, or at least that’s what the HM4 suggests. Released in 2013, the HM4 Final Edition is the last of the HM4 line, which the company introduced in 2010. Only 100 were made, including just eight Final Editions.
Büsser drew airplanes and built models in his youth and his passion is evident in the HM4’s twin indication pods, which look like tiny turbine engines mounted on the aft fuselage of some kind of retro-stealthy jet. You can see the intricate innards of the HM4—two mainspring barrels connected in parallel and two vertical gear trains that drive the indicators—through a sapphire display panel. Making each panel took 185 hours of machining and polishing. The entire watch comprises 311 components, all made specifically for this timepiece.
Each indication pod features an aviation-style instrument panel indicator. One crown dedicated to its own pod controls winding, while another crown on the other pod sets time. Power reserve is up to 72 hours, and an indicator modeled after MB&F’s battle-axe design motif shows the remaining reserve.
While it’s hard to imagine actually wearing an HM4, which measures 54 mm wide by 52 mm long by 24 mm high, it’s not hard to appreciate its beauty and to understand why the MB&F watchmakers embarked on this exercise in what they say is “three-dimensional architectural horology.” As the company explains, “MB&F is not a watch brand, it is an artistic and micro-engineering concept laboratory in which collectives of independent horological professionals are assembled each year to design and craft radical horological machines.”