Classic Flyoff - DC-6 v Viscount

Much has been written about Australia’s Two-Airline Policy enacted in 1952, which the federal Liberal government of the day under Robert Menzies, rightly or wrongly, forced upon the Australian travelling public.

The major result of that now defunct policy was that both domestic airlines in the late 1950s – TAA and Ansett-ANA, were compelled to fly parallel schedules and to operate common aircraft equipment. Two aircraft types had to be shared by each – the DC-6B and the Viscount, and this included cross-leasing, where Ansett-ANA exchanged two DC-6Bs for three TAA Viscounts. Whilst both airlines would schedule identical types for the same routes, often as not, a Skychief and a Viscount would be pitted against each other.

This treatise endeavours to point out the more obvious operational aspects of these two aircraft types, but the actual rationale for their being selected for Australian service is not the focus here.

The Douglas product came in two main versions with little difference in cockpit setup or procedures. The Viscount on the other hand, had variants within variants, all requiring slight differences in operation due to different marks of engine, variations in gross weight and even differences in certain cockpit controls. Each type was powered by four engines, the Douglas using tried and proven supercharged Pratt & Whitney Double Wasp piston engines, whilst the smaller Vickers used the then quite novel, Rolls Royce Dart turbine propeller engines.

The Douglas DC-6B Skychief.

The DC-6 prototype first flew as the USAF’s XC-112 on 15th February 1946, and was later civilianised as a DC6. It was essentially a pressurised, stretched and higher power version of the famous DC-4 employing the same wing but now built from stronger alloys, with a gross weight of 100,000 lbs. Further developed into the C-118, a militarised version of the slightly longer (by 60 inches) and higher gross weight (107,000 lbs.) DC-6A freighter, the type was ordered in quantity by both the US Air Force and US Navy.

The joint airline launch customers for the DC-6 were American & United Airlines, both commencing operations on 27th April 1947. First Australian operator of the type was British Commonwealth Pacific Airlines from 19th November 1948 with four in service by December of that year. On 1st December 1953 two more were delivered to Australian National Airways, albeit secondhand and Trans Australia Airlines leased one for a period of four months from KLM on 4th December of that year, ostensibly to cover a forecast Christmas rush.

Employing the stretched fuselage of the DC-6A without the large cargo door, but with more windows and seating, the prototype DC-6B first flew on 10th February 1951. This was to become the definitive, most popular and most widely built version of the series and was loved by aircrew and maintenance personnel alike. Airline managements everywhere also considered that on a seat/mile basis, it was the most economical airliner ever built to that time. The DC-6B gross weight was now a hefty 107,000 lbs. and the engines fitted were the excellent Pratt & Whitney R2800-CB17’s rated at 2,500 h.p. with water methanol injection.

The only Australian operator of new DC-6Bs was ANA, with the first of four being delivered on 11th February 1955, and all were in service by October 1956.

TAA and Ansett-ANA each obtained a secondhand DC-6B in November 1963, bringing their Skychief fleet up to three each, in accordance with the then-current Two-Airline Policy. The Douglas name applied to the DC-6 series was “Skychief” which followed on from previous Douglas aircraft “Sky” names such as the DC-3 Skyliner and the DC-4 Skymaster.

Vickers Viscount.

The Viscount prototype first flew as the Vickers Type 630 on 16th July 1948, and the enlarged and definitive V700 series completed its maiden flight on 28th August 1950, using 1400 h.p. Rolls Royce Dart turboprop engines. Airline launch customer British European Airways commenced Viscount operations in January 1953, followed by Air France in March of the same year. Large orders followed on from North America, followed by smaller orders worldwide.

Ironically the Dutch Fokker F.27-100 Friendship, which first entered airline service with Aer Lingus in December 1958, carried 40 passengers using only two RR Dart prop-jet engines as opposed to the V700s four RR Darts lifting an initial load of 48 passengers.

The V700 design maximum weight was 56,000 lbs, and was progressively increased to 60,000 lbs. The V800 series maximum weight started out at 69,000 lbs but was later increased to 72,500 lbs. In both models increasingly powerful versions of the Rolls Royce Dart turboprop engine were fitted, permitting these increases in gross weight.

The first Australian Viscount 700 delivery was to TAA on 5th October 1954, with their sixth
aircraft being accepted on 2nd April 1955, this being the first to have removable slipper tanks for added range. TAA was unique among local V700 operators in using wing-mounted slipper tanks. Four more V700s were delivered in 1956, two in 1957 and the last three in 1958, for a TAA fleet total of fifteen.

Only one other Australian operator received new V700s – two for Butler Air Transport, the first being accepted on 27th September 1955 and the second on 14th September 1956. The fact that B.A.T. had prop-jets before Ansett was a major factor in the hostile takeover of Butler by Ansett in 1959. A total of seventeen V700s were used in Australian airline service.

The slightly longer and heavier Viscount 800 first flew on 27th July 1956 and was delivered to launch customer British European Airways in February 1957. The initial Australian V800 operator was Ansett-ANA, accepting the first of four new aircraft on 12th March 1959, the remainder being delivered by May of the same year. Two secondhand V800s were delivered to Ansett-ANA in 1960 and 1962 respectively.

TAA bought two new V800s in May and June 1959 respectively, but also obtained a secondhand example in 1962. The RAAF introduced two secondhand V800s in September 1964 permanently fitted with larger-capacity later model slipper tanks and they were the only Australian V800 operator to carry these devices. A total of eleven V800s flew in Australian markings.

Operational Comparisons.

Author’s note: All figures quoted are approximate only but within the ballpark, as actual conditions of weather and gross weight could vary on the day.

The DC-6B Skychief was universally feted as a true pilot’s aircraft based on excellent handling, performance and airframe strength combined with a roomy, well laid out cockpit and large cabin. Unfortunately the Viscount did not enjoy the same reputation.

In the collective opinion of pilots who had flown both types, the Viscount was critically under-engineered in many areas, requiring crucial limitations in operational service. The Viscount cockpit was poorly designed and ergonomically difficult, making it quite taxing on flight crews. These combined drawbacks suffered by the Viscount undoubtedly pointed to the type’s poor safety record in Australia – four fatal crashes from a national fleet total of only 28 aircraft. The Viscount had a similar record overseas.

The single major incident involving an Australian DC-6B was the shedding of a propeller blade soon after take-off from Essendon. The aircraft involved in this incident was VH-INA. With the #3 engine hanging below the level of the undercarriage, a landing in that configuration was out of the question. With considerable skill the pilot managed to shake the engine off the wing and into Port Phillip Bay, graphically illustrating the aircraft’s considerable ruggedness, followed by a safe landing back at Essendon.

A cost advantage held by the Viscount over the Skychief was that it could operate with only two technical crew, as opposed to three on the DC-6B, which required a Flight Engineer. TAA’s marketing department also widely touted the smoothness of flying in the turbine-powered aircraft and the Viscount’s large oval windows with attendant passenger appeal.

Climbing speed for the Douglas was 160 Knots whilst the Vickers climbed at 180 Knots, meaning that a Viscount on a parallel departure could be disadvantaged if the Douglas got off first. Once on the way friendly competition between aircraft to get there first was often the case.
Cruising speed for the DC-6B was usually around 240 Knots at 16 – 20,000 feet compared to the Viscount’s 250 Knots at somewhat higher levels. The Viscount had higher specific fuel consumption than the Skychief, but turbine fuel (Avtur) being cheaper than gasoline (Avgas) helped to offset this. The Skychief’s passenger capacity was about one-third greater than the Viscount, with almost double the freight capacity of the smaller propjet in the DC-6B cargo hold.

Where the DC-6B really shone by comparison was in the descent phase, as it was able to maintain 250 Knots all the way down whilst the Viscount needed to reduce speed to at least 200 Knots or less dependant on flight conditions for a safe descent, because of airframe structural considerations. Due to close scheduling under the Two Airline Policy, this sometimes caused consternation between the two aircraft and air traffic control.

Another disadvantage of the Viscount was its relatively short range when carrying a commercial payload and this was drastically in evidence on the Perth route, flying into the usual headwinds. A Viscount having to land at Kalgoorlie for fuel was not uncommon. TAA solved the problem by fitting removable slipper tanks at Adelaide, but then had to accept a penalty in payload or passenger numbers. The DC-6B did not have these quirks and could comfortably accommodate the headwinds.

Comparing the two types in Australian domestic airline service, and regardless of what some experts may have espoused, the Skychief was the more economical, reliable and proven aircraft when considering its sound maintenance and flight operational record, excellent seat/mile economics and its comfortable environment for both passengers and working crew.

Conversely, the Viscount was widely considered as being under-engineered, relatively cramped and suffering from questionable airframe strength. Due to poorly designed cockpit ergonomics, occasional crew confusion when changing directly from one variant to another model in the same duty tour, caused unnecessary difficulties and sometimes quite close calls.

In hindsight, the Viscount could perhaps have been a better performer in the critical areas of operations and maintenance economics, had the manufacturer devoted time and finance to a more thorough research & development program. However the Viscount did outlast the Skychief on the Australian domestic airline scene by some three years.

End of the line.

Ansett-ANA retired their last “Straight Six” (DC-6) in March 1960, whilst the last DC-6B ceased airline duty in July 1968. The last Viscount 700 was scrapped in May 1970, followed by retirement of the final V800 in April 1971. Thus ended the era of two dissimilar airliner types compelled to operate under the demon of government enforced parallel scheduling on common routes.

Footnote: Other than the odd privately flown Viscount, none are believed to be in commercial passenger service anywhere. However the Skychief soldiers on both as a commercial freighter and as a firebomber in parts of the Americas, whilst a number are flown privately.