Air Defense

GDF-001 / GDF-002 anti-aircraft gun

Also known as
  • Oerlikon GDF
  • Oerlikon 35 mm twin cannon

The GDF-001 and GDF-002 are early Oerlikon GDF twin 35 mm towed anti-aircraft guns. Weaponsystems says the family entered service in 1963, and from the GDF-002 onward it added a Ferranti GSR sight and digital data-bus linkage for Skyguard fire control. In Yemen, open-source documentation places GDF-001/GDF-002 guns in the pre-war Yemeni Army inventory and available to Yemeni battlefield parties after the Houthi takeover, but does not support a precise engagement or shootdown claim.

GDF-001 / GDF-002 anti-aircraft gun, Towed twin 35 mm anti-aircraft gun, Air Defense
Image source: Japanese L90 or GDF-002 35 mm twin cannon

Role in Conflicts

Profile / Specs

Profile

Origin
Switzerland
Type
Towed twin 35 mm anti-aircraft gun
Service note
Late 1950s-present family; Yemen record tied to the 2014-2015 takeover period
Designer
Oerlikon Contraves
Designed
Late 1950s
Unit cost
Not publicly documented for GDF-001/GDF-002
Produced
1960s onward for the GDF family
Number built
Over 2,000 units sold to over 30 nations

Specifications

Crew
3 on GDF-001/GDF-002 class guns
Armament
Two 35x228 mm Oerlikon KDA L/90 autocannons
Rate of fire
550 rounds per minute per barrel; 1,100 rounds per minute combined
Effective range
About 3.2 km against aircraft and 4 km against ground targets
Ammunition
Original models carried 112 ready rounds plus 126 additional rounds on the carriage
Weight
About 6.3 t empty; 6.7 t loaded
Fire control
GDF-001 used the XABA sight; GDF-002 added the Ferranti GSR sight and a digital data bus for external Skyguard control
Mobility
Four-wheel towed carriage, normally moved by a 6x6 truck
Variant Split

The GDF-001 and GDF-002 are early production variants of the same 35 mm twin-gun family. The main documented differences are the sighting fit and the external fire-control interface.

VariantKey distinctionOperational note
GDF-001First production versionUses the original XABA sight and relies on external Super Fledermaus control.
GDF-002Updated production versionAdds the Ferranti GSR sight and a digital data bus for Skyguard fire control.

Variant differences summarized from the GDF source on this page.

Variants
  • GDF-001
  • GDF-002
Skyguard Control Compatibility

Weaponsystems links the GDF-002 onward family to Skyguard radar fire control.

Compatible itemItem typeCompatibility evidence
Skyguard air defense system, Ground-based short-range air defense system, Air DefenseSkyguard air defense systemRadar fire-control system

The GDF source says the GDF-002 added a digital data bus for integration with Skyguard fire-control radar.

Sources: GDF

Timeline

GDF-001 / GDF-002 anti-aircraft gun Key Events

  1. GDF family development

    Weaponsystems says Oerlikon Contraves developed the GDF in the late 1950s as a towed anti-aircraft gun family.

    Sources: GDF

  2. Entered service

    Weaponsystems lists the GDF as entering service in 1963 and still in service today.

    Sources: GDF

  3. GDF-002 adds external fire-control linkage

    Weaponsystems says the GDF-002 introduced the Ferranti GSR sight and a digital data bus for Skyguard fire control.

    Sources: GDF

  4. Documented in Yemen

    Oryx documented pre-war Yemeni Army GDF-001/GDF-002 guns available to Yemeni parties after the Houthi takeover.

    Sources: Handbook Of Pre-War Yemeni Fighting Vehicles

Media

GDF-001 / GDF-002 anti-aircraft gun Videos

GDF-001 / GDF-002 anti-aircraft gun Images

GDF-001 / GDF-002 anti-aircraft gun, Towed twin 35 mm anti-aircraft gun, Air Defense - view 1
Source: Swiss Oerlikon GDF 35 mm Anti-aircraft Gun with Skyguard Fire Control System 1979
GDF-001 / GDF-002 anti-aircraft gun, Towed twin 35 mm anti-aircraft gun, Air Defense - view 2
Source: Dubendorf Flieger Flab Museum - 35mm Oerlikon twin cannon anti-aircraft gun
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Sources

GDFPublisher: Weaponsystems.net | Note: Supports Oerlikon GDF-001/GDF-002 background, manufacturer, design history, service entry, production total, variants, fire-control linkage, armament, crew, rate of fire, range, ammunition, weight, and mobility specifications. | Accessed: 2026-06-20Handbook Of Pre-War Yemeni Fighting VehiclesPublisher: Oryx | Note: Supports 2014 Yemen Civil War context: GDF-001/GDF-002 guns were fielded by the pre-war Yemeni Army and documented in 2015 as available to Yemeni parties on the battlefield after the Houthi takeover. | Accessed: 2026-06-20U.S. Destroyer Arrives Off Saudi Arabia Amid Plans To Bolster The Kingdom's Air DefensesPublisher: The War Zone | Note: Supports regional 2014 Yemen Civil War air-defense context around Houthi-claimed drone and missile attacks and Saudi Oerlikon GDF/Skyguard point-defense deployments; not used as the direct Yemen battlefield-use source for this entry. | Accessed: 2026-06-20Japanese L90 or GDF-002 35 mm twin cannonPublisher: Wikimedia Commons | Note: Supports image provenance for a Japanese-produced GDF-002/L90 example released into the public domain by the photographer. | Accessed: 2026-06-20Swiss Oerlikon GDF 35 mm Anti-aircraft Gun with Skyguard Fire Control System 1979Publisher: Wikimedia Commons | Note: Supports image provenance for a Swiss GDF gun with Skyguard fire-control system, credited to ETH-Bibliothek Zurich / Comet Photo AG under CC BY-SA 4.0. | Accessed: 2026-06-20Dubendorf Flieger Flab Museum - 35mm Oerlikon twin cannon anti-aircraft gunPublisher: Wikimedia Commons | Note: Supports image provenance for a museum-preserved 35 mm Oerlikon twin cannon photographed by Ank Kumar under CC BY-SA 4.0. | Accessed: 2026-06-20