In the early 1960s Hawker Siddeley and the British Aircraft Corporation were becoming the dominant players in the British aircraft manufacturing sector. Lagging behind them was Handley Page, which had been famous for its heavy bombers for the RAF. However the company spotted a niche in the market for a design capable of carrying between 12 and 18 people in a speedy manner.
The reality was that Handley Page simply didn't have access to the funds required to go toe-to-toe with the big boys on a larger airline project. Initial indications were that the gap they'd identified did indeed exist, and an order for 20 aircraft was received from the USA before the design had even been completed.
The original HP.137 Jetstream design dates back to 1965 and accommodated 12 passengers in six rows, separated by an aisle running down the centre of the fuselage. The long nose was quite distinctive and came about as efforts to improve streamlining were explored. The fuselage was circular and eased pressurisation issues, meaning the aircraft could fly higher and faster than its competitors. The cross-sectional area of the cabin was so small that the floor had to be lowered to allow passengers the ability to enter and egress the aircraft while stood up. The only way this could be achieved was if the main wing spar ran through the inside of the cabin, but this posed a trip hazard to passengers.
Construction of a number of parts of the airframe was subcontracted out, with wings being built by Scottish Aviation and the tail section being assembled in Canada by Northwest Industries. Final assembly then took place at HP's brand new Radlett Aerodrome facility in Hertfordshire, though the test programme eventually migrated from there to Turbomecca's factory airfield in the south of France. Turbomeca was the manufacturer of the aircraft's Astazou XIV engines, a turbo-prop derivative of the highly successful turbo-shaft design, perhaps best known for its use in the Gazelle helicopter.
The Jetstream 1's first flight, using airframe G-ATXH, had taken place under the control of the company's Chief Test Pilot, John Allam, from Radlett on August 18th 1967, but as the test programme progressed it soon became clear that all was not well. The engines were, surprisingly, posing by far the greatest obstacle to the project. Not only were they underpowered they were also proving to be incredibly temperamental, so the relocation to France allowed issues to be ironed out quickly, while at the same time taking advantage of the region's better weather conditions.
Having fitted a pair of American-made Garrett AiResearch TPE-331 engines to the fifth prototype, HP managed to secure an order from the US Air Force for 11 examples of what it dubbed the C-10A - the Jetstream 3M so far as HP was concerned. Aside from the engines, this model was to be fitted with a cargo door and would allow carriage of 12 seated pax or six stretcher-bound patients. Ultimately the order was cancelled with the Air Force citing 'late delivery' as the reason for the cancellation.
36 examples of the original Jetstream 1 were delivered in the year following the first flight of the initial production aircraft which took place on December 6th 1968.
By this stage it had become patently obvious to HP that the original Astazou engine simply wasn't up to the task and the Jetstream 2 was launched with uprated Astazou XVI engines, each capable of delivering an additional 125shp over its predecessor, meaning the 'new' aircraft had a total of 1930shp to call upon from its two engines.
Handley Page had originally estimated that the Jetstream project would cost £3m to reach product maturity, but the reality was a long way from that. The ongoing delays had pushed the cost above £13m, and only three examples of the Jetstream 2 had been completed by the time the company was declared bankrupt and the production line closed in 1970.
A consortium led by Scottish Aviation considered that interest in the Jetstream was high enough to pursue continued production. A company called "Jetstream Aircraft" was formed at Sywell Aerodrome near Northampton to allow production to continue, with a further ten Jetstream 1s rolling off the line.
Scottish Aviation took product development of the Jetstream 2, which it renamed the Jetstream 200, on alone at its Prestwick facility. The company's faith was rewarded in August 1972 when the Royal Air Force awarded a £9m contract for 26 Jetstream 201 aircraft. These would be known as the Jetstream T.1 and be used to replace the Vickers Varsity in the multi-engine training role. The 201 benefitted from a further uprated engine, the Astazou XVID, with an additional 31shp at its disposal.
HP had unsuccessfully courted interest from the RAF in 1969, but this more positive outcome came following a fly-off against the Aero Commander 690 the previous year.
Not all of the 26 aircraft order would be new builds, however. The allocated serial block spanned XX475 to XX500 and the first seven of those aircraft had all carried civilian registrations. Indeed, XX475 was actually built in 1969 as a Jetstream 1 and saw service in the US with Regency Income Ventures and Highland State Minerals before being bought back by Scottish Aviation for conversion to T.1 standard for the RAF.
The first Jetstream T.1 made its maiden flight on April 13th 1973 and all deliveries, resplendent in the red and white colour scheme that the fleet would sport for the duration of its service, had been completed by early 1976.
After a review in 1974 had concluded that the initial 26 aircraft order exceeded the RAF's multi-engine pilot training requirement, a number of airframes were flown into storage at RAF St Athan, pending a decision on their future. Indeed, multi-engine training was stopped completely in December 1974, just five months after the first Jetstream course had commenced, with 5 FTS being disbanded in the process.
After reassessing its needs, the multi-engine training programme recommenced in November 1976. At the same time the RAF had concluded that fourteen of its recent acquisitions were now surplus to requirements (a further airframe, XX477, had been lost in an accident at Little Rissington in 1974 following a fuel feed problem which led to the loss of both engines) and these were offered to the Royal Navy to replace its ageing Sea Prince fleet, which was used for Observer training purposes. In order to make them fit for purpose some modification was required, most notably the installation of the MEL E190 weather and terrain-mapping radar and the fitting of consoles in the cabin for the students. In the process the Jetstream T.2 "Flying Classroom" had been born.
Deliveries to the Royal Navy began in October 1978, though it was September 1984 before all aircraft had been received by 750 NAS at RNAS Culdrose, Cornwall.
In that same year Scottish Aviation, along with a host of other British aviation companies, was nationalised into British Aerospace, and BAe believed that further development of the Jetstream was warranted. The Mark 3 was powered by newer Garrett engines producing a flat 1020hp with a thermodynamic limit of 1100shp, and offering an increased maintenance interval over its Astazou predecessors.
Crucially, this increase in power made it possible for BAe to offer the aircraft in an 18-seat fit, still with six rows of seats, but with the aisle offset, meaning each row now consisted of two seats, then the aisle, and then a further seat.
A water methanol option was also available for the engine, allowing the aircaft to operate at a maximum take-off weight (MTOW) which meant it could operate from more airfields around the world, particularly in Australia and the US.
Known as the Jetstream 31, this latest derivative first flew on March 28th 1980 and finally generated the levels of interest that Handley Page had envisaged when it began development some 15 years earlier.
A further two Jetstream 2 series airframes were sourced from the civilian market for Royal Navy use, F-BTMI which became ZA110 and 9Q-CTC which became ZA111. These were among the first examples of the Jetstream 2 built with manufacturer years of 1970 and 1969 respectively. Their first flights with military identities came in July and December of 1981 and, unlike their red and white painted brethren, these two were delivered in the blue and white colours that the whole fleet would wear till retirement.
Lt Chris Wood, a staff pilot with 750 in the mid-1980s recalls how the Jetstream was used back then:
"The Basic Observer Course (BOC) consisted of basic Dead Reckoning (DR) navigation (either clockwise or anti-clockwise around the Scilly Isles), radar navigation (taking radar fixes), radar homings to ships, low level navigation (for which the student was in the RHS up front), medium level navigation (done as a trip somewhere - usually Prestwick for a visit to the Scottish Mil ATC centre) and if they were lucky an overseas trip (Berlin was a favourite!) The final phase was Tactical Navigation, which would start as a medium level navex somewhere and then it would change once airborne, usually to something involving some low level!
"The normal crew was one Pilot, a Qualified Observer Instructor (QOI - formal training for QOIs started in the mid '80s) who was in the RHS for take off and landing but went back into the cabin once airborne, and a student Observer. The aircraft had two consoles but most training sorties were flown with only one student.
"Course sizes grew during the early '80s, my course initially consisted of 20 Pilots and five Observers. By the time I was on the staff at 750 the Observer courses were much larger, with 12 or more students on each course. It wasn't unusual to have eight aircraft launch in a five minute stream!"
The Royal Navy placed an order for four brand new Jetstream 31 aircraft in 1985, to augment its fleet of T.2s. Deliveries all took place in 1986 and this more modern variant received the Jetstream T.3 designation, giving 750 NAS a total complement of 20 airframes by the end of that year.
For their intended role the T.3s were equipped with a Doppler fed Tactical Air Navigation System (TANS) and the Racal ASR360 multi-mode radar, the antenna for which was located underneath the fuselage. Chris recalls their arrival:
"The T.3s were ordered for Observer training and were fitted with a radar and consoles. However early tests showed that the radar had a very limited range (supposedly only around 25 miles - not much use on an aircraft cruising at three miles a minute!) - it was a development of a maritime navigation radar. It wasn't long before the radar was removed, dumped in the hangar and the aircraft fitted with seats.
"After being operated by 750 in the communications role for a while, the aircraft were moved to Yeovilton to replace the ageing Herons of Heron Flight."
At the end of the '70s most of the aircrew at 750 came from the fixed wing world, which isn't surprising given that it wasn't long after Ark Royal had been decommissioned, and lots of Phantom, Buccaneer and Gannet crew needed to be placed somewhere. However during the early to mid-'80s it was felt that, as all the students would be heading for the helicopter world, it made sense to train helicopter pilots to fly the Jetstream, as they could relate to the environment that the students were heading for. Chris explains:
"Fixed wing training for helicopter pilots during the '80s consisted of two weeks at Plymouth flying the Britannia Flight Chipmunks (learning to land, then stop!), six weeks at 771 NAS at Culdrose flying the Sea Devon for multi engine training and then Jetstream conversion with 750 NAS. I found the Jetstream a real handful, it was very heavy on the controls and, being a turboprop, a small movement of the power levers (throttles!) resulted in a big change in power output. The Devon had been very docile but the Jetstream was a brute (initially!) However once I got the hang of hauling it around, I thoroughly enjoyed flying it, it was very satisfying being able to tame it!
"The Jetstream 31 was quite a different beast to fly. The T.2 was actually good at what the RN used it for, and it was easy to fly low level. The T.3 was good for going places but was a bit fiddly and not so suited for low level. Just to make life a bit more interesting for the pilots it had an extra flap setting, which was easy to miss if you were used to flying the T.2!"
A further engine upgrade was planned by BAe in 1985 which came to fruition in 1988, with the latest variant dubbed as the Jetstream Super 31 or Jetstream 32. Some 386 examples of the Jetstream 31 or 32 had been produced by the time production ceased in 1993.
The Royal Saudi Air Force took delivery of two Jetstream 31 aircraft between late-1986 and mid-1987 to train its Weapons Systems Officer students. Only one of the two remains extant after a crash on approach to Dhahran on October 14th 1989.
750 NAS suffered its own tragic loss of an aircraft at Portland in '89. XX489 was displaying at a Cadet Day on May 8th when it stalled during a wingover and fell into the sea, killing both pilots.
With the new found success of the '31, BAe had the confidence to take the design one stage further with the Jetstream 41, a stretched version of the '31 intended to take on Embraer's Brasilia, Dornier's Do328 and the Saab 340. It was capable of seating 29 passengers in the same two-by-one layout employed in the Jetstream 31. Unsurprisingly, the '41 incorporated a further uprated engine, the -14 version of the Garrett TPE-331 (though now owned by Honeywell), delivering first 1500shp and later 1650shp - almost double the power provided by the original Astazous.
100 examples were built between 1992 and 1997, though no follow up military orders were received.
In 1996 XX475, which was one of the aircraft offered to and converted for Royal Navy use, passed into the hands of the Defence Test Evaluation Organisation (DTEO) and later the Defence Evaluation Research Agency (DERA) at West Freugh. It was reportedly modified to allow the deployment of sonar buoys, replacing an Andover previously used for that purpose. As with almost all of the test aircraft from that era, it was repainted into the trademark 'raspberry ripple' colour scheme with bold titles. Today it lives at Northbrook College, Shoreham, and plans are afoot to get the aircraft into ground running order.
XX485 and XX490 were delivered to the Uruguayan Navy as A-875 and A-876 in December 1998 having been deemed to be surplus to the Royal Navy's requirements. Both have reportedly now been withdrawn from service by their new owners.
March 17th 2004 represented the beginning of the end for UK military operation of the Jetstream when the RAF's 45(R) Sqn at RAF Cranwell replaced its aircraft with much newer Beech King Air 200s. With age had come a lack of reliability and the fleet simply wasn't able to achieve the required 5400 hours per year to allow the courses to be completed. This in turn had created a need for some of the flying hours to be contracted out which simply wasn't sustainable or ideal, hence the earlier than planned arrival of the King Air.
Two of the RAF's examples found homes at RAF Museum Cosford and Newark Air Museum respectively, while several others went to RNAS Culdrose and RAF Shawbury for spares recovery to support the ongoing operation of the Royal Navy's fleet. Another example also ended up at Northbrook College.
In July 2008 it was announced that the Jetstreams of 750 NAS were to be replaced by a Cobham FR Aviation subsidiary supplied, modified and maintained fleet of new Beechcraft King Air 350ERs. At the time it was expected that the Jetstream would bow out of service in 2010. The news came following the May announcement that the Lockheed Martin UK/VT Ascent consortium (VT has since been acquired by Babcock International Group) had been awarded the contract to provide the UK Ministry of Defence's 25-year Military Flying Training System.
Heron Flight and the T.3 followed the RAF's T.1s into the history books on September 29th 2008 with three aircraft going into storage at RAF Cranwell and the other to RAF Shawbury. The aircraft were offered for disposal in October 2010 with three of the four being allocated registrations on the US-register.
And so we come to March 2011 and the Jetstream's UK military swansong. With the final Jetstream 32 week / 70 flying hour Basic Observer's Course ending on 7th March, it just remained for 750 NAS to prepare to bid farewell to the type.
The days leading up to the 11th saw a number of formation practices, made up of the entire remaining fleet of six aircraft, take place with the official send-off tour routing Falmouth-Yeovilton-Exeter-Dartmouth (Britannia Royal Naval College)-Newquay-Truro-Falmouth-Lands End-Predannock then loop round over Helston for a flyby and landing at Culdrose. "Mercury Formation" was led by Mr Charles Leuchars, a former RAF fast jet pilot who described his part in the making of history simply as a "Great honour".
The flypast on the 11th was not quite the final day of UK military Jetstream operations, however, as, three days later, XX481/CU560 - the first airframe delivered to the Royal Navy - was launched for one final time for a photoshoot with an example of the type that would be replacing it.
In 32 years service, 750 NAS has amassed in excess of 100,000 flying hours with the Jetstream, graduating almost 1000 students from the Basic Observer Course in preparation for the commencement of type specific Advanced Conversion and Operational Conversion phases of training. At the time they bowed out, this could have meant specialist warfare skills and systems operation training for Merlin HM.1, Sea King AsaC.7 or the Lynx Mk 8 platforms.
The Jetstream's replacement, given the name "Avenger", will operate as part of a true tri-service programme. It will be one of the first elements of the Ascent MFTS arrangement to become fully operational and will lead to some changes in the way that Observer training is delivered.
Whereas in the past the whole 70 hour course had been delivered at Culdrose, students will now head to Barkston Heath to undergo a four-week common core ground school, followed by a further four week familiarisation phase and then a five week elementary navigation training course. Upon successful completion, students will spend a week receiving leadership training in Wales. Only then will they progress to Culdrose where 70 hours ground tuition will be received via synthetic means as well as around 50 hours actually in the air.
The Squadron's flying staff will be a mix of military and civilian personnel and it's anticipated that the first course will commence at Barkston Heath in July, with students reaching Culdrose in October.
The Commanding Officer of 750 NAS, Lieutenant Commander Nick Armstrong, had the following to say about the Squadron's future:
"It is because 750 Squadron has been around for so long doing the same role that people tend to assume it doesn't change much and in a sense that is true: the core skills that are required by every Observer haven't changed a great deal but the technology and equipment we use certainly has.
"Our job is to prepare and select young men and women to fly the Merlin, Lynx and Sea King helicopters as they conduct a variety of missions around the world, ranging from Anti-Piracy in the Gulf of Oman, Ground Surveillance in Afghanistan to the more traditional Anti-Surface Warfare, Anti-Submarine Warfare and Search and Rescue.
"As the variety of tasks we have to achieve continues to grow, Observers have to become even more flexible, adaptable and capable than ever before. We achieve this by continuing to teach many of the things those Observers of 50 years ago would have been familiar with, but on modern equipment with modern techniques that more closely reflect how we operate on the Front Line. The King Air 350 ER Avenger will allow us to do exactly that."
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