Survey Flying – This type of flying can be particularly satisfying because the benefits of accurate piloting and navigation are clearly reflected in the results.
In the ‘60s before the advent of modern technology such as satellites, drones, Lidar and related software most survey work was done using aircraft of various descriptions. For example, the surveys for the HF Verwoerd (now Gariep) and PK Le Roux (now Vanderkloof) dams were flown in an Aero Commander 680F at an altitude of about 24,000 feet.
The camera hatch was more or less on centre towards the rear of the cabin, control wires and plumbing having been rerouted to allow for the hole in the floor. However, cabin heat was supplied by a Janitrol fuel fired heater in the nose which could not be used as its exhaust flowed backwards under the fuselage and the relatively hot air distorted the photography. The -40°C/Fahrenheit temperatures intersected, so flying at this altitude included fleece lined boots and gloves, but even so operating times were limited without heating as the shivers set in.
In sharp contrast low-level survey operations had to be operated in the heat without the advantage of air conditioning. This could lead to fatigue after just a few hours and at least one case of a detached retina occurred when the navigator’s eye was severely jarred by contact with the floor mounted navigator’s sight eyepiece in turbulence.
A succession of particularly tragic cases occurred to a survey operation using de Havilland Beavers. The first one occurred in the foothills of the Waterberg while the Beaver was ascending the profile of a fairly steep koppie and did not have sufficient power to continue the climb or turn away and collided with the ground. All three crew members were killed. Sometimes an issue with this type of flying can be a relatively inexperienced pilot with not much time on type being used while he gains experience towards charter or airline flying.
The insurance investigating team had no sooner returned to base when they were greeted by the news that yet another Beaver on survey had crashed and burned out in the Northern Cape, killing three experienced crew.
The next day the team set out again for Springbok, some four hours flying time in an ancient Seneca One. The investigation revealed that the Beaver had collided with a small rising rocky outcrop. The flying technique used was apparently to maintain the same power setting in level flight and then use flaps to ‘balloon’ over the obstacle. It seemed that something had gone awry during the application of this procedure.
The return flight, of about four hours, arrived in the dark south of the home airfield and very nearly collided with tree-covered high ground, the co-pilot fortunately seeing the trees in time and pulling back on the control column. Three fatal accidents in three days would have been far too much for the mind.
Survey fortunately has its lighter moments. A crew based at an airstrip in the Free State were probably on the ground with nothing to do one day just before they moved on. The airfield name was marked in white stones, and they decided to rearrange some. The airfield name ‘Luckhoff’. No prizes for guessing which stones were rearranged.
Survey flights sometimes operated under marginal requirements. I remember flying as navigator in the 680F in Bains Kloof below mountain top level, when a 90% forward overlap on succeeding photographs was required – this for better stereoscopic results. Flying at the normal speed would result in the camera working so fast that it would have likely jumped out of its mounts, so the speed was reduced and some flap applied. This made the aircraft more vulnerable from a safety point of view.
The aircraft was written off many years later on a mountain in the Karoo while on a survey mission and involved one fatality and an injury to another crew member.
Today many more surveys can be carried out with minimum safety exposure to the crew and equipment due to the arrival of the new technologies and the results more quickly obtained and processed due to advanced software.
From a military surveillance point of view the Lockheed SR-71 Blackbird has to take the cake. Developed in the 1960’s by the Lockheed ‘Skunk Works’ this extremely advanced aircraft has to be one of the most interesting in many categories and still holds many records. One is the flight from America to Farnborough in one hour 54 minutes and some seconds.
WHAT CAN WE LEARN?
Situational awareness is particularly important when flying low level and possibly over-concentrating on the work in hand. The priority ‘fly the damn plane’ remains the cardinal rule.