Most of the world's aerial survey fleet have an average age of around 50 years, with many exceeding 14,000 hours flying. However, there's a good selection of aircraft manufactured today that meet the requirements. Lyndon Yorke discusses the market...
Over the past few years, aerial survey operators have seen the useful life of an airborne sensor reduce from around 25 years’ service (as per analogue instruments) to about three years (for digital sensors) even though they are carried in aeroplanes that could be anything up to 50 years old.
Today the popular survey platforms like Twin Commanders, PA31 series, Cessna 400 series plus older Beech types can be expensive to support and operate and sometimes present additional surprises to operators in the form of ADs, SIDs and other mandatory requirements especially on the older pressurised platforms.
During the 1960s, 1970s and 1980s many of the aircraft types incorporated factory-installed camera hatches or pre-STC-era-approved/certified modifications. How things have changed today!
There are companies throughout Europe and North America offering a wide range of STCs covering camera hatches and other sensor housings, and collectively they facilitate modifications on most aircraft types, old and new. Some supply self-install kits for the simpler types (i.e. Cessna 206 or PA31), but for the modification of pressurised aircraft the controlled workshop environment of an STC holder will be required.
Today instigation of a new STC for a camera hatch has become a long-winded, highly expensive exercise requiring the services of a Part 21 design organization, which in turn needs to get a lot of complex data from the OEM’s typically metallurgical data, load factors and stress figures. Unfortunately, most OEMs no longer supply such data, particularly US companies who are concerned about long-term liability responsibility.
Such requirements apply not only to floor camera hatches but also geophysical sensor housings on tail booms and wing tips. FLIR turrets and other strange looking appendages all, ultimately, require an STC for which there are specialist companies qualified to undertake the work.
Diamond DA42 MPP
Into the Twenty-First Century
Today, the aerial survey industry must take into account the ever-increasing cost of maintaining these old aeroplanes, including the (lessening) availability of spare parts and those surprise ADs, SIDs and more.
Responding to those considerations, there is a new generation of factory-modified survey airplanes which can facilitate survey clients’ requirements. Popular models include those from Vulcanair, Tecnam and Diamond at the lighter end of the scale with these types facilitating about 50% of the platform demand.
Diamond’s DA42/62 is ideal for carrying smaller/lighter sensors and is now well established and highly valued by the special missions surveillance operators using FLIR type sensors and airborne telemetry. The single-engine types from Cessna (i.e. the Cessna 206 and Cessna 208 series) have proved extremely good aircraft for usage in developing countries.
Gaining popularity is an excellent rival to the Cessna 208 – the Pacific Aerospace 750XL, a roomy, versatile platform with the ability to have up to three floor hatches and multitask survey, medevac, para dropping and more.
Pacific Aerospace P750 XSTOL
Meanwhile, the Vuncanair P.68R and Tecnam P2006T SMP’s high-wing and retractable landing gear allows for a ‘no view obstruction’ for external cameras and operator FoV (Field of View). The high wing keeps two economical engines completely cleared from dust and any foreign object that could damage the propellers and the engine through the air intakes.
The option to use automotive fuel (MOGAS) as well as AVGAS allows Tecnam P2006T (and Diamond types) to dramatically reduce direct costs, making it possible to fly in areas where AvGas is difficult to find or prohibitively expensive. The key success of this solution is mainly related to the high quality/price ratio and the many possibilities according to the needs of the final user/operator.
At the top end of the scale (for civilian users) are the Beechcraft King Air series 90/250/350 for which specialist modification companies offering ‘off-the-shelf’ camera hatch STCs that enable such modifications on both newer King Air and earlier models. Pilatus now offers a special missions version of the PC-12 which is slowly gaining market penetration.
And then on the horizon there are some potentially interesting twins being developed in Eastern Europe.
Aficionados of the DC-3 will be pleased to read that the Turbine powered/revamped version produced by Basler (the BT67) has proven to be a very valuable survey asset, especially for geophysical operations in the Arctic area and Africa.
Vulcanair P.68 Observer
The VulcanAir P.68 series (ideal for low/medium altitude operations at lower speeds) has proven to be highly popular, and there are many survey P68 aircraft operating on survey missions worldwide. To complete the operating range Vulcanair has recently introduced a Special Mission configuration of its twin-turbine A-VIATOR aircraft featuring two camera hatches.
Finally, the newly-certified Tecnam P2012 offers 11 seats and comes in a Special Mission configuration: High wing, Lycoming piston engines and all-weather ability makes this aircraft an interesting option for operators worldwide.
Larger Cabin/Higher Payload Platforms
There is still considerable demand for larger cabin class aircraft that are able to carry a wide range of sensor types. These vary from large format cameras on gyrostablised mounts, lidars, hyperspectral, multispectral, Thermal, SAR, FLIR, oblique looking cameras, spectrometers, geophysical and research instruments.
For commercial operators a typical platform needs to have a range of more than 1,000nm while offering capability to fly both at low altitude at relatively low survey speeds, and at higher flight levels and higher speeds.
Moreover, aircraft in this arena ideally need to be capable of carrying more than 300kg payload in sensors and associated support equipment, two crew, plus seating for an observer (as required by some governments).
Turbine power will tend to ensure fuel availability worldwide for survey operators. Some countries, however, impose aeroplane age restrictions, stipulating that aircraft typically should be no older than 15-20 years, so the requirement for younger platforms is now a serious consideration.
Although an expensive purchase for a commercial operator, the operating costs for a new(ish) airplane will soon prove cost-effective with greater reliability and easier servicing than for older aircraft.
What’s the Cost of a Survey Modified Aircraft?
An older piston twin that has been survey modified can be purchased for anything between €150k-300k. For older standard aeroplanes like the Piper PA31 series, it is possible to retrofit/modify with EASA/FAA certified hatches for less than €50k, but you still end up with an old aeroplane.
Today, to purchase a modern/near-new survey airplane will cost from about €1.5m up to €4m, depending on type and modifications required. Although sensors are getting smaller and lighter, demand for a modern surveying platform is a serious consideration.