The Observer or B-Uhr watches began to be supplied by the German Air Ministry to members of the Luftwaffe, under the specifications cited in ordinance FL 23883 starting in 1936 and were intended for Luftwaffe pilots. It reflected that the boxes should be dull and made of aluminized brass, gray bronze or steel, the latter less common; have the pressure cover mounted; have a diameter of 55 mm since the caliber came from a pocket watch; Contrast-rich dial, usually white on a matte black background; Radioactively contaminated luminous hands and indices coated to allow visibility at night. The crown was designed especially strong and effective enough that the watch can be adjusted even with gloves. The central seconds hand should have a stop mechanism at 12 o’clock in order to be able to synchronize the watches with a radio signal or the captain, before each of the flight operations. These watches served as a means of navigation in addition to the cockpit instruments, compass and altimeter during visual flights common at this time.
The common characteristics, included in FL-23883, were mainly:
- 55mm diameter case, marked FL-23883.
- Oversized crown, so it can be handled with gloves on.
- Central seconds hand.
- Stop seconds at 12 o’clock.
- Breguet spiral.
- Antimagnetic protection.
- Hands and dial with luminescent material (at that time, radio).
- All had to be tested as marine chronometers by the German Maritime Observatory, near Glashutte.
It was very important that the mechanics of the watches were of the highest precision. The technical characteristics of these watches were specified by the Reichs Luftfahrt Ministerium (ministry of aviation). The position on the wrist, the design of the dial, the font and also the dimension of the crown were defined by this ministry.
In turn, they should have large closed leather straps so they can be fastened over thick leather jackets or even worn on the leg, even with gloves on. It must be taken into account that at that time airplanes suffered great vibrations and this size facilitated better reading of the dials.
Inside the pressure bottom they had to be indicated – engraved by this
order-, the word Beobachter Uhren or B-Uhr, name of the construction company,
team number (127, corresponded to the B-Uhr), team number
watch/mechanism, the reference FL 23883 and finally, the name of the manufacturer
and city.
The reference or code FL23883 indicated that these were navigation parts («Fl» fligth) («23») equipped with accessories («88»). The «3» at the end was the specific reference to his «B-Uhren» quality. This engraving was located on the outside of the case on the opposite side to the crown.
There were two types of design for the sphere:
- Type A. Clean dial. The hours were marked on the outside of the dial.
It was ridden by: IWC, Wempe and Stowa. - Type B. Slightly more ornate dial. The hours were marked in an inner circle and on the outside of the dial, the markers were every five minutes.
All these observer watches were set as navigation chronometers and individually tested by a special department installed near Glashüte, the so-called German Maritime Observatory. It was a great challenge for manufacturers to produce this type of observation clock during World War II due to the high level of precision and reliability required.
As mentioned before, in air missions the pilots of each squadron synchronized the seconds of their watches. To do this, the crown of the watch was removed and the needle was set to zero and simultaneously, at the captain’s command, the crowns were inserted, which is why all the watches were equipped with a stop-second hand.
