Plans to retain the Nimrod R.1 in service until 2025 have been put in doubt as a result of an increased operational tempo, and because of concerns about the airworthiness of the first-generation Nimrod. The aircraft also lacks space and power for capability growth, as well as being cramped.

Nimrod R.1 XV249 at Incirlik AirBase, Turkey waiting for its crew for a Combined Task Force Operation Northern Watch sortie on November 5, 2002. This aircraft is an MR.2 hastily converted to R.1 standards under Project Anneka after one of the original trio was lost.

A topside view of a Nimrod R.1 shows off much of the aircraft's antennae array - above the fuselage, in the noses of the wing tanks and in the tailcone. The aircraft wears the recently adopted grey colour scheme, which has replaced the hemp scheme previously used.

Рабочие места операторов разведоборудования
Inside the rear compartment of a Nimrod R.1, looking aft past the Flt Lt Elint supervisor at console 7 and the silver-haired Master AEOp Comint supervisor at console 8.

Nimrod R.1 has a flight crew of four, and a mission crew of up to 24, with ten Elint specialists (including the mission supervisor and an Elint supervisor), 13 Comint operators (including a supervisor), and two ad hoc positions. There are 13 numbered consoles, eight of which have two seats, and three auxiliary consoles. The right-hand seat in each pair'is referred to using the 'a' suffix, so that Console 4 has an Elint operator in position 4, and a Comint operator at position 4a.

RC-135U Combat Sent обеспечивает важной развединформацией президента и министра обороны США, руководителей различных управлений Пентагона и высшее военное командование на ТВД.
The RC-135U carries the PPMS with antennas under the nose and on the wingtips. The configuration has changed over the years.
Two RC-135U Combat Sents are operated by the USAF and are its closest equivalent to the Nimrod R.1 in the Elint role. However, they are strategic, rather than tactical intelligence gathering aircraft.

Reportedly the favoured option to replace the Nimrod R.1, the Baseline 8 version of the RC-135V/W Rivet Joint is an excellent Comint platform, but lacks the Nimrod R.1's comprehensive Elint capabilities.