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The Encyclopedia of Horology

Wristwatch · Military navigational wristwatch

IWC Mark 11 RAF-Issued 6B/346 Wristwatch

Partially verified

This is an RAF-issued IWC Mark 11 military navigational wristwatch, with case markings indicating an issue date of 1948. Encased in a 36 mm stainless steel case with fixed lug bars, the screw-down back is engraved with the British military Broad Arrow, the stores code 6B/346, and issue number 575/48. The seller reports it is powered by a manual-wind 17-jewel Calibre 89 movement and fitted with a matte black replacement service dial bearing an encircled 'T' denoting tritium luminescence.

Case back of IWC Mark 11 wristwatch showing British military broad arrow, 6B/346 stores reference, and 575/48 issue number
Case back of IWC Mark 11 wristwatch showing British military broad arrow, 6B/346 stores reference, and 575/48 issue number — Vintage Watch Specialist. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
vintagewatchspecialist.com
Category
Wristwatch · Military navigational wristwatch
Maker / attribution
IWC (International Watch Co.)
Reference
6B/346
Catalogue / lot identifier
vws4477cs
Source-reported date
1948
Country
Switzerland
Source-reported serial
575/48

Source-reported attribution and specifications are not independent authentication. A listing does not establish present ownership, current display, availability or permission to reproduce.

Object description

Military Identity and Provenance

This timepiece is identified as an IWC Mark 11, specifically issued as navigational equipment for the British Royal Air Force. The case back serves as the primary record of its military markings, featuring the broad arrow engraving alongside the stores designation '6B/346'.

The individual issue marking '575/48' is present on the case back. The source states that the '/48' suffix denotes the 1948 issue year, placing the watch at the beginning of Mark 11 production.

Evidence for this section
  • “The stainless-steel caseback carries the British military Broad Arrow, followed by the stores designation 6B/346 and the individual issue marking 575/48.”
  • “That final /48 denotes its 1948 issue year, placing this example right at the beginning of Mark 11 production.”

Case Construction

The watch is housed in a 36 mm stainless steel case. Features include fixed bars between the lugs for strap attachment and a screw-down case back secured with six perimeter notches.

Visible surface scratching and wear are noted across the stainless steel case back. The case measures approximately 46 mm from top to bottom with an 18 mm lug width.

Evidence for this section
  • “The watch has a 36mm stainless-steel case, with approximately 46mm from top to bottom and an 18mm lug width.”
  • “Screw-down case back with six perimeter key notches.”
  • “Visible surface scratching and wear across the stainless steel case back.”

Dial and Movement

The watch is powered by a manually wound 17-jewel IWC Calibre 89 movement. The movement itself is not visible in the provided imagery.

The dial is described as a later RAF service replacement featuring an encircled 'T' mark, which signifies tritium luminescence. The source notes that this replaces the original 1948 radium-lumed dial.

Evidence for this section
  • “Inside is the manually wound IWC Calibre 89”
  • “The dial should therefore be described as a later RAF service replacement , rather than represented as the dial originally fitted to the watch in 1948.”
  • “The dial also carries the encircled T marking associated with tritium luminous material.”

Open research questions

  • Does the current movement serial number align with the case issue year of 1948?
  • Are there internal case back markings indicating specific maintenance depots or dates of the service dial replacement?
  • What is the physical condition of the movement?

Source evidence

Recorded claims and source quotations for IWC Mark 11 RAF-Issued 6B/346 Wristwatch
FieldSource-reported valueSource quotation
Issue Markings6B/346 - 575/48“The stainless-steel caseback carries the British military Broad Arrow, followed by the stores designation 6B/346 and the individual issue marking 575/48.”
CalibreCalibre 89“Inside is the manually wound IWC Calibre 89, a movement that became inextricably linked with the Mark 11”
Case Diameter36mm“The watch has a 36mm stainless-steel case, with approximately 46mm from top to bottom and an 18mm lug width.”
Dial Service ReplacementRAF service replacement with circled T“The dial should therefore be described as a later RAF service replacement , rather than represented as the dial originally fitted to the watch in 1948.”
Case Dimensions36mm diameter, 46mm height, 18mm lug width“The watch has a 36mm stainless-steel case, with approximately 46mm from top to bottom and an 18mm lug width.”
Movement17-jewel IWC Calibre 89“Powered by the legendary 17-jewel Calibre 89.”

Visible details

  • Screw-down case back with six perimeter key notches.
  • Case back engraved with a British military broad arrow, '6B/346', and issue number '575/48'.
  • Fixed bars between the lugs for strap attachment.
  • Fluted winding crown at the 3 o'clock position.
  • Visible surface scratching and wear across the stainless steel case back.

Research qualifications

  • The source reports the dial is a later RAF tritium replacement rather than the 1948 radium original.
  • The movement and dial are not visible in the provided image.

Photograph identity and source facts were screened before import; rights clearance remains pending.

Consulted source

1948 IWC Mark 11 RAF-Issued 6B/346 – Calibre 89 - Original Condition – Vintage Watch Specialist

Reviewed 2026-10-22 · Record 17d87f02cc

Terms in this record

Glossary explanations for terms named in this object’s record.