The Beobachtungs-Uhren ("B-Uhr", observers watch) were made for the WWII Luftwaffe. These large watches contained high-quality pocket-watch movements for use in aircraft navigation. They were attached to the arm with long leather straps that fit around the outside of the flying clothing.

There were five manufacturers: A. Lange & Söhne, IWC, Laco, Stowa, and Wempe. Features that the watches have in common:

• Cases 55 mm in diameter, marked "FL 23883"
• Large crowns for use with gloves
• Indirect center seconds
• Stop ("hack") seconds
• Breguet balance springs
• No shock protection

For collectors, the IWC are the most highly valued, followed by Lange, and then the others. After WWII similar watches were made in East Germany by the GUB.

Manufacturer and Movement	Front	Back	Notes
A. Lange & Söhne (Glashütte) Movement: Cal. 48/1			The movement has a large (20 mm) balance and 17 jewels set in chatons, and often uses a swan-neck regulator. Because of the size of the order, the watches were assembled by a number of firms, including Huber (Munich), Felsing (Berlin), Schieron (Stuttgart), Suchätzle und Tschudin (Pforzheim), and Wempe (Hamburg).
IWC (Schaffhausen) Movement: Cal. 52 SC			A total of 1200 cal. 52 SC (offically "52T-19''' H6 S.C.") movements were made, and around 1000 went into the B-Uhr made by IWC. The cal. 52 SC was 43.15 mm (19 lignes) x 6.0 mm, 16 jewels, and 18,000 bph. The movement bore a swan-neck regulator and were adjusted in 6 positions and tested at the Gesundbrunnen observatory in Glashütte. The 55 x 16.5 mm cases were numbered 1033201 to 1034200 and had an additional anti-magnetic inner case.
Laco (Lacher & Co., Pforzheim) Movement: Durowe cal. D5			Durowe (Deutsche Uhren-Rohwerk) was part of Laco. The 22-ligne, 22-jewel movement has a very large (22 mm) balance and a simple regulator.
Stowa (Walter Storz, Pforzheim) Movement: Unitas (Tramelan) cal. 2812			The 18-ligne, 20-jewel movement has a swan-neck regulator and is nickel-plated with Geneva stripes.
Wempe (Hamburg) Movement: Thommen (Waldenburg) cal. 31			The movement has a snail-cam fine regulator.

Additional Images

• Lange with strap
• Lange inside case back
• IWC and IWC Mark 11
• Laco inside case back
• Laco side profile
• Stowa inside case back
• Wempe outside case back

References

• Manfred Fritz, "High-flyer," Watch International, no. 4, pp. 40-41, 2001/2.
• Helmut Kahler, Richard Mühe, and Gisbert L. Brunner, Wristwatches: History of a Century's Development, Fourth Edition, Schiffer Publishing Ltd., 1999.
• Konrad Knirim, Reichs-Luftwaffe: Aviation Observers Watch.
• Konrad Knirim, Die Uhren deutscher Streitkräfte, 'Klassik Uhren, December 1996.
• Becker von Waldemar, Marine-Navigationsuhren und Luftwaffen-B-Uhren: A. Lange & Söhne, 'Klassik Uhren, April 1998.
• Z. M. Wesolowski, A Concise Guide to Military Timepieces, 1880-1990, Windrow & Greene Ltd., 1996.

Images are from Gisbert A. Joseph, Roland Kammer, Michael Friedberg, among others.