13 June 2021

Utah Williamson Burnett's Private Air Service


The Manapouri power station was built in the 1960s. This project involved the construction of an underground power house and a 10 kilometre tail race tunnel to carry water from Lake Manapouri to Deep Cove in Doubtful Sound as well as the Wilmot Pass road. The contract was let to an American-New Zealand consortium of the Utah Construction and Mining Company, in association with Burnett Motors Ltd of Ashburton, and W Williamson Construction Company of Christchurch. The joint venture became known as Utah-Williamson-Burnett.  

To facilitate accommodation for the workers in the remote Deep Cove the 1930’s era TSMV Wanganella trans-Tasman passenger liner was saved from being scrapped. The ship sailed to and was moored in Doubtful Sound’s Deep Cove in August 1963. For the next six years the ship provided hostel accommodation for the construction workers. In April 1970 a tug towed the Wanganella to Hong Kong in theory to be repaired and returned to service. Faced with prohibitive costs the ship was sold in Taiwan where she was scrapped.

The Wanganella moored in Doubtful Sound. A magnificent history of the Wanganella can be found here http://ssmaritime.com/Wanganella.htm

In 1960 the Wilmot Pass walking track was the overland access between the western side of Lake Manapouri and Doubtful Sound. The 21 km unsealed road was constructed between 1963 and 1965 to accommodate heavy equipment transporters moving equipment loads from ships off-loading at Doubtful Sound for the power station construction. With a large work force at Deep Cove and with a lack of overland access an air service was essential. Initially Southern Scenic Air Services' Cessna 180 floatplanes and Tourist Air Travel's Grumman Widgeons were used to provide air access but it was clear a larger aircraft was required.

On the 15th of September 1963 it was announced that Utah-Williamson-Burnett had acquired a newly refurbished 12-seat Grumman G73 Mallard from Trans Australian Airlines. It was envisaged that the Mallard would make at least one return flight a day between Deep Cove and Invercargill carrying passengers, workers and freight as required. Ex-Fleet Air Arm and Southern Scenic Air Services' Te Anau Cessna 180 floatplane pilot Don Nairn was been appointed chief-pilot for the Utah-Williamson-Burnett operation and he flew the aircraft across the Tasman along with a Trans-Australian Airlines check pilot and an engineer. Don Nairn wrote in NZ Wings, I had never seen a Mallard, but as I had previously flown four Grumman types during the war, including the Goose and Widgeon amphibians, I was eager to get my hands on another of their pedigree line of aircraft. VH-TGA left Sydney for Norfolk Island on the 12th of October 1963 and then flew on to Whenuapai the following day. A TAA co-pilot was arranged to fly with Don Nairn on the ferry flight and for the first month of operations. It was placed on the New Zealand register as ZK-CDV on the 15th of October 1963. (The aircraft retained its TAA colour scheme, and hence the logo at the head of the post is because it featured on the aircraft rather than being representative of the consortium)

 Pilot for the amphibian operation Don Nairn in front of the Grumman Mallard. Source : Grumman-Mallard aeroplane, at Invercargill. Whites Aviation Ltd: Photographs. Ref: WA-61278-F. Alexander Turnbull Library, Wellington, New Zealand. /records/23254592

Operations began on the 29th of October 1963 with the Mallard flying from Invercargill to Deep Cove at the head of Doubtful Sound. The normal payload of the aircraft was one ton, this being made up of passengers, freight and mail. The aircraft was also used as an air ambulance and could carry seven stretchers. Don Nairn, the operation's pilot explained the logistics of the Deep Cove flights in NZ Wings in 1996. All I was required to carry was an assistant to help with mooring and to operate the anti-squat strut at the rear of the hull. I was given Louis Walkenshaw, a keen Utah William Burnett staff youth the next day, and we flew into the Cove with an initial load of freight to test out my planned procedures for mooring and disembarking onto an anchored floating pontoon at Deep Cove. Prior to leaving for Melbourne to collect the Mallard I had asked to have a long low pontoon made up and anchored a couple of hundred yards out from the Wanganella as a temporary loading platform. This would have to be used until a turnaround area was built ashore, which was estimated to take only a few months. However, Deep Cove wasn't named on a whim and the steepness and depth of its shoreline were such that it took almost two years of spoil dumping before an area large enough to run the Mallard ashore was completed. To enable me to bring ZK-CDV alongside the pontoon I had a long floating rope run out straight downwind from the pontoon by one of the company's launches which always stood by during my takeoffs and landings. After landing I would taxi across this rope with my assistant standing in the bow with a boat hook. The moment he had a turn of rope around the bow cleat I cut the engines and drifted to a halt as we weather-cocked downwind, then my bowman slowly pulled us alongside the pontoon where another helped to secure us. The loads of men and freight were offloaded onto the pontoon and we were all taken by launch over to the ship, where I found out who and what were intended to go back to Invercargill. 

A couple of magnificent photos of the Grumman Mallard ZK-CDV at Doubtful Sound's Deep Cove. The Mallard and the pontoon.

 The Mallard and the Wanganella, both moored in Deep Cove

Don Nairn continues, Throughout all the first two years the Wilmot Pass weather remained the key to my ability to get directly into and out from Deep Cove. The weather there is the fastest changing of any I have experienced, anywhere I have flown. Many a time I came in through the pass under broken cloud, only to find the whole Deep Cove area completely closed under eight/eighths cloud by the time I had unloaded the plane. I then had to return to Invercargill by flying the 22 miles down Doubtful Sound and then around the coast. This took one hour 15 minutes, compared with the 45-minute direct flight. In his autobiography, Gold Wings and Webbed Feet, Don talked about at times having to land on the Sound closer to the sea and then having to taxi for up to two hours to reach Deep Cove.

Utah Williamson Burnett was not keen to have fuel available for me at Deep Cove because of the fire risk, so I had to leave Invercargill with fuel for the 45-minute trip over, plus 30 minutes' gas for possible abortive attempts to get out of Deep Cove, then an hour 15 to come home around Puysegur Point, plus the mandatory 45 minutes reserve. All this added up to a disposable load of one imperial ton only, generally eight or nine passengers with the heavy weights of luggage and tool kits people took into the Cove with them. On occasions we took the full 12 passengers with little or no luggage. Except for emergency rush flights in the case of serious accidents, the Mallard was always loaded to its limit of 12,500 pounds. For the first two years before the Wilmot Pass road connecting Deep Cove with West Arm on Lake Manapouri was completed, the only access to Deep Cove was by sea from Bluff, walking from West Arm or flying in by water-based aircraft. Helicopters were not around in our part of New Zealand then. Nearly half the direct flight into Deep Cove was over the 6000 foot mountains of Fiordland, but for many weeks of the year these are under cloud and I would fly below the cloud base to West Arm. Then I would fly between the mountain ranges and around the corner up to and through Wilmot Pass if it was still open, or else backtrack and proceed through some of the escape routes I knew from my floatplane days. In these conditions the Mallard's manoeuvrability and beautifully harmonised controls were appreciated to the full, as I was always faced with running into below-VFR conditions around the next corner. 

Apart from Fiordland's weather, the second problem I faced was that of landing on glassy water when I flew from brilliant sunshine into the inky blackness of early-morning shadow which would cover the entire Deep Cove area during the winter. Under these conditions it was invariably flat calm so I used to set up an instrument approach from well up the sound and set my altimeter to the height of a feature, known to be 100 feet above sea level, as I flew past it. I then sat glued to the DIG, ASI, A/H and altimeter until, at a rate of 100 feet per minute, some 60 seconds later I could sense the downwash from the motors on the elevators and feel the Mallard gently enter the water. It was like descending into a black inkwell as at no time during these landings was I able to make out the actual surface of the water. When both the West Arm-Deep Cove road and my turn-around area near the Wanganella were finished, life on the job became comparatively easy for me. Gone were the obligations of trying everything to get into Deep Cove when I was urgently needed to fly casualties to Invercargill. When the weather was unfavourable all I had to do was take the plane to West Arm (Lake Manapouri), to where the injured personnel would have been brought by road over Wilmot Pass.

One year on from the first flight, by the end of 1964 the Mallard had made 896 flights, 648 of these into Deep Cove and of those 126 were around Puysegur Point carrying 6,082 passengers, 321 tons of freight and a number of air ambulance cases. 

When the road over the Wilmot Pass was completed at the end of September 1965 the aircraft's role changed. Workers shuttled to and from Deep Cove by launch over Lake Manapouri and then bus over the Wilmot Pass. The aircraft use was reduced to being used for the transport of urgent supplies, the carriage of VIPs and as an ambulance. 

With the demand for the aircraft greatly reduced in November 1967 the Manapouri Messenger reported that the Mallard was to be given to the Fiji Government for use as an air ambulance for Fiji, Tokelau and Niue Islands. However, the departure of the aircraft, a Grumman Mallard, will depend on how quickly arrangements can be made for a suitable replacement aircraft to serve the power scheme. The assistant Commissioner of Works, Mr F. R. Askin, said recently that the Ministry of Works and the contractors were studying several possible replacements. Union officials on the project site have been given an assurance by the Ministry of Works and the contractors that continuous air-ambulance cover will maintained. The Chairman of the combined union's committee at Deep Cove (Mr R. P. Green) said in a telephone interview that the committee had first learned of the decision to transfer the. Mallard from the Manapouri area some weeks ago. Although there was a road into the works site, the frequency of accidents made it necessary to have an aircraft "on the job", Mr Green said.

Utah Williamson Burnett's Grumman Mallard at Invercargill

Grumman Mallard ZK-CDV on the turnaround area Deep Cove with the Wanganella behind 

The decision was overturned and the Mallard remained in service until December 1968. Two weeks before the Mallard ended service a massive explosion severely injured a number of workers. The weather is Deep Cove prevented the aircraft flying there but with the road over Wilmot Pass the wounded were ambulanced to Lake Manapouri's West Arm from where they were flown by the Mallard to Invercargill. All seven stretchers were in use. 

The final flight to Deep Cove was operated on the 10th of December 1968. The Grumman Mallard flew a total of 2,763 flights between Invercargill and Deep Cove (162 of them going round Puysegur Point)  supporting the Manapouri Power Project, carrying a total of 13,526 passengers, 287 stretcher cases and walking wounded and 737 tons of freight.

In early 1969 the Mallard was flown to NAC in Christchurch for some refurbishment and a new paint scheme for Fiji’s Air Pacific carrying the name "Na Secala." ZK-CDV was cancelled from the New Zealand civil aircraft register on the 21st of February 1969 being registered VQ-FBC in Fiji.

And a final word on ZK-CDV from Don Nairn, The Mallard proved to be ideal for this project. Anything smaller would have been inadequate, and anything bigger would not have been able to turn around in the many places in Fiordland which I confidently flew through in the Mallard. It was a real pleasure to handle, both in the air and on the water where its take-off performance was effortless.


  1. Fascinating article, this aircraft is still active in the US as N2950 flying from Monterey, CA to Minden-Tahoe, NV last Sunday, 6 June. It has been owned by Steve Hamilton, Reno, NV since 2006. Richard Currie

  2. Brilliant piece of history recounted there.