Hawker Siddeley Nimrod R1

Nimrod R1
Nimrod R1
Role	Signals intelligence
National origin	United Kingdom
Manufacturer	Hawker Siddeley
First flight	21 October 1973
Introduction	1974
Retired	2011
Status	Retired
Primary user	Royal Air Force
Number built	4
Developed from	Hawker Siddeley Nimrod

The Hawker Siddeley Nimrod R1 was a signals intelligence aircraft operated by the Royal Air Force. The aircraft was a conversion of the existing Nimrod maritime patrol aircraft, with all of the electronic equipment and armament optimised for anti-submarine and anti-ship warfare, and search and rescue, replaced by equipment for the gathering of communications intelligence and electronic intelligence.

In 1958, 192 Squadron took delivery of a pair of Comet R2 aircraft, converted for use in the signals intelligence (SIGINT) gathering role, to replace the Avro Lincoln and Boeing Washington aircraft being used in the role. At the same time, the squadron was renumbered as 51 Squadron. Almost as soon as the aircraft entered service, attention was placed on working on the specifications for a replacement aircraft, as it was envisaged that the Comet would reach the end of its useful life by the early 1970s. The decision to proceed with a new SIGINT aircraft was taken in 1964 by the London Signals Intelligence Committee, which determined that the usefulness of retaining an airborne intelligence gathering capability justified the significant cost of replacing the Comet. In comparing the cost of potential aircraft to undertake this role, including a variant of the Boeing 707 (which the USAF had at the time ordered as the RC-135), the cheapest option was decided to be a variant of the Nimrod maritime patrol aircraft then in development for the Royal Air Force.

Although the Nimrod option was identified as the cheapest, the cost of procuring and modifying three aircraft was still estimated at £14m, a significant proportion of the budget for SIGINT operations. As a consequence of this, in 1967, Burke Trend, the Cabinet Secretary, recommended that the aircraft be declared part of the United Kingdom's nuclear weapons programme, using the rationale that the intelligence gathered by the aircraft would be used to providing data for targeting. This allowed the cost to become part of the overall budget for RAF Strike Command, tying SIGINT in with the RAF's operations of nuclear weapons.

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