Detailed Interpretation Of Key Features Of Pilot Watches

As we all know, there is an official standard definition (ISO6425) for the characteristics of diving watches, but another popular category-pilot watches, is not. According to the needs of the wearer, each brand has its own unique views on pilot watches. Of course, there are always some key elements that make pilot watches stand out.

   Aviator watches are popular for their practical aesthetics and legibility. Today, pilot watches are more used to show identity and taste, and are no longer instruments of aviation flight. But just like diving watches, pilot watches were born for practical purposes. It is generally believed that it was Louis Cartier who created the first pilot’s watch for Albert Santos Dumont to facilitate flight timing. The technical specifications of the earliest pilot watches were very basic, far from military watches in the mid-20th century, which shaped the design and characteristics of modern pilot watches.

The first Breguet Type 20 military chronograph watch, specially ordered for French naval aviation pilots in 1958, a total of 500 pieces, delivered in January 1960.

   Military power need not be limited to a certain brand. The French Navy, the British Ministry of Defence, the German Air Force, and the Italian Air Force often use watches from different manufacturers to the same specifications, which have spawned many legendary models such as the Type 20 and Type 21 chronographs, the Mark series and the B-Uhren wrist Table and so on.

German pilot wearing Hanhart watch

Cockpit instrument

   Take the German Beobachtungsuhren (aka B-Urh) watch as an example. This watch is very large and can reach 55 mm in diameter. The generous size is enough to cover the large manual winding movement that pocket watches are used to, but B-Urh is still a watch after all. The B-Urh watch is equipped with a soft iron inner case to protect the movement, which has the necessary anti-magnetic properties of aviation, while using Breguet hairsprings. The wearer can pull the crown, pause the central second hand, and adjust the time. The oversized diamond or onion crown can be easily operated even when wearing gloves. The B-Urh also comes with a very long leather strap that pilots can easily wear even with a thick leather jacket.

IWC B-UhrCalibre52T.S.C. Watch (Ref.IW431)

   The specifications of the B-Urh watch say it all. The size of the pilot’s watch should be large enough, the dial should be as contrasting as possible, and it should be fluorescent (matte black dial with large numbers and time scales coated with radioactive material) for easy reading. Watch operation is also as simple as possible to avoid errors. At the same time, accuracy and precision are paramount. Taking into account the harsh conditions of use, ideally, pilot watches should also be shock-resistant, anti-magnetic, and able to withstand sudden pressure drops (to prevent mirror displacement).

The IWC Mark XI watch is the inspiration for most of the brand’s pilot watches.

   Regarding pilot watches, we often encounter various doubts, such as what is this? What’s the use of that? Why is it so designed? In this article, we will introduce the key features of pilot watches in detail, hoping to bring some help to beginners.

Triangle logo

   High-contrast, clear and easy-to-read displays have always been a distinctive feature of pilot watches. The dial is usually discarded to the simplest, with striking fluorescent hands and hour markers, and Arabic numerals that can be easily read.

   The 12 o’clock position of the dial is usually set with a triangular mark-a fluorescent equilateral triangle, with a dot on each side (B-Uhr style watch). The pilot can quickly distinguish the vertical direction of the dial and find the 12 o’clock s position. Time information is clear at a glance, day or night.

Flyback timing

   The flyback timer function saves time when recording multiple periods of time and is therefore popular with pilots. Traditionally, for multi-segment timing, three steps of stop, reset and start are required, and the flyback timing function only needs to press the reset button once to complete all steps. A quick reset helps pilots perform waypoint navigation and grid search.

   Pictured above are two well-known pilot watches with flyback timing. One is the Breguet TypeXX3800ST watch, a modern version of the pilot’s watch commissioned by Breguet in the 1950s and 1960s. The second is the Zenith PilotCronometroTipoCP-2Flyback watch, inspired by the CronometroTipoCP-2 watch commissioned by the Italian Air Force through the Roman retailer A.Cairelli. Both watches are equipped with this special mechanism, as are their prototype antique watches.

Fluted bezel with red markings

   The red marker on the rotatable fluted bezel can be used as a chronograph or countdown, for example for monitoring navigation or bombing (such watches are usually military tools). Pilots rely on the map to determine the time to reach a specific location, and they can quickly read the elapsed time by pointing the red marker at the minute hand. The grooves on the bezel help achieve precise, non-slip operation.

   Pictured above are two antique military pilot watches with grooved bezels and red markings. One is the Hanhart chronograph from the 1930s. The speedometer and rangefinder scales on the bezel are used to measure navigation information such as the average speed on the runway. The second is the Tutima Glashütte Fliegerchronograph watch, which also has red markings on the bezel.

Diamond or onion crown

   In the early era of aviation, the cockpit of the aircraft was designed to be open. Pilots were exposed to severe cold conditions and needed to wear thick gloves to prevent frostbite. Proper crown design is the key to easy watch operation. Therefore, most pilot watches are equipped with huge crowns (ie BigCrown watches), with the most common onion head and diamond shape.

   Pictured above are two modern pilot watches inspired by antique timepieces. Zenith chose a round onion crown (as did the brand’s vintage pilot watches), while IWC used a sharper cone-shaped diamond crown (inspired by the B-Uhr watch).

Soft iron inner shell

   Mechanical watches are threatened when exposed to magnetic fields. Universal tool watches require protection against the negative effects of magnetic fields, especially for pilot watches, because the cockpit is one of the most magnetic environments that a watch may encounter. Traditionally, watchmaking brands use the Faraday cage principle to achieve magnetic protection: a soft iron inner case surrounds the movement and protects it from magnetic fields. For example, the IWC has commissioned the Mark XI watch, and its specifications include the use of a soft iron inner case.

Cutaway view of a watch with a soft iron inner case

   With the advent of anti-magnetic materials, modern pilot watches are becoming less and less equipped with such a heavy and space-consuming inner case. The movement parts are made of silicon or non-magnetic alloy, which has anti-magnetic properties.

Flying slider

   Flight slider is an invention of Breitling, used in the brand aviation time series. The flight slider is a mechanical calculator designed for pilots. It can be called a mini computer in the pre-digital era and can perform various types of flight calculations. The calculation is based on the fixed scale on the dial and the scale on the two-way rotating bezel. Breitling uses the rotating bezel and logarithmic scale to determine fuel consumption, speed, distance, flight time, and unit conversion.

Hour angle

Original Longines timepiece for Charles Augustus Lindbergh
   This rare feature is used to help pilots determine geographic location. Charles Augustus Lindbergh perfected the system designed by Philip van Horn Hooms, and worked with Longines to develop a timepiece. The hour-angle watch synchronizes the second hand with the radio signal, and calculates longitude based on the hour angle between GMT and true solar time.

Long stud strap

   This is a typical feature of the German Beobachtungsuhren watch (observation watch), equipped with a long studded calfskin strap so that pilots can wear it on the sleeves of flight jackets. Rivets are used to ensure that the strap is firmly fixed to the watch, as shown in the Longines Limhème watch mentioned earlier.

GMT display

   More modern, non-military features commonly found on pilot watches. The GMT display is a very useful feature for travelers traveling in different time zones, including pilots. Introduced in the mid-1950s, the Rolex GMTMaster is the prototype of the GMT watch, designed by Pan American Airlines in cooperation with Rolex to equip the crew. The GMT (or second time zone) is indicated by an additional hour hand, combined with a 24-hour dual-color day and night display bezel. (Photo / text watch home compiled by Xu Chaoyang)