With aircraft only being invented at the dawn of the 20th century, aviation archaeology is one of the newest fields in archaeology, and the study of underwater aviation archaeology (UAA) is in its very earliest stages. The nature of the material means that aircraft can be (and have been) found in every conceivable environment, from the jungles of Papua New Guinea to under 200 feet of ice, with bodies of water from freshwater lakes to oceans acting as the final resting places for thousands of aircraft worldwide.
These photographs show a British long range fighter/bomber (Bristol Beaufighter serial number T5174) which ditched in the waters off St Julian's Bay in Malta shortly after takeoff on St. Patrick's Day 1943, and now lies underside up in 37m of water. All pictures copyright T. Gambin University of Malta with permission.
Aviation archaeology enjoys significant overlaps with maritime, conflict and historical archaeology, and can be defined as the scientific study of the material remains of all aspects of humanity's interaction with the air via the medium of flight. This includes the study of all infrastructure connected to aircraft such as factories and airfields, as well as the aircraft themselves. Underwater aviation archaeology (UAA) is the underwater facet of this.
With aircraft being a relatively modern invention, it is unsurprising that the study of them as tools to shed light upon the past is also a relatively recent development, and one not without its challenges. These include the retrieval of aircraft for use as (subsequently unprovenanced) spare parts, the destruction of original material on recovered aircraft and its replacement with brand new parts for display purposes, and most important and poignant of all, the presence of human remains.
The beginnings of a wider movement to preserve historic aircraft could be said to have commenced in the 1960s, with the newfound popularity for historic aircraft at air shows and with the foundation of the National Air and Space Museum (NASM) in the USA in 1962. However, the idea that historic aircraft could be scientifically studied and treated as archaeological artefacts only began to be seriously postulated in the 1980s, as evidenced by such projects as the retrieval of the 'Loch Ness Wellington' (aka 'R for Robert') and the foundation of The International Group for Historic Aircraft Recovery (TIGHAR), both in 1985.
Since then, there have been archaeological studies on a number of submerged aircraft, both still submerged and recovered. A selection of these can be found in the Bibliography.
The scale of the crashed aircraft heritage is vast, in large part due to the role of aircraft in war, in particular World War Two. The US Navy alone conservatively estimates that at least 12,000 of its aircraft were lost during World War Two, while the figure for aircraft crashes of all nationalities and causes in the UK for the same period is estimated at 10,000. Whilst a proportion of these would of course have crashed upon land, factors including increased range and their adaptation to seaborne operations e.g. deployment on aircraft carriers, has meant that many of these also crashed at sea.
Strangely, despite the scale of the resource, the potential of UAA has remained largely untapped. Pioneering work has been carried out (particularly on flying boats) by the Western Australian Museum, work which continues under their 'Broken Wings' programme. In the Pacific, the Bentprop Project (while its primary mission is the retrieval of missing US airman from past wars) utilises a state-of-the-art AUV to seek out crashed aircraft, and then uses high-definition photogrammetry to digitally record the aircraft it then finds. In the UK, the retrieval and subsequent commencement of conservation of a German Do-17 bomber from the Goodwin Sands in June 2013, an aircraft formerly classified as 'extinct', is the latest high-profile instance of UAA.
The composition of aircraft presents unique challenges (and opportunities) in the realm of conservation. Whilst early aircraft had wooden frames covered with canvas or plywood, the development of lighter and stronger metal alloys (especially of aluminium) and advances in engine technology in the 1930s saw a shift towards the widespread use of metals for almost all parts of aircraft.
Aluminium came to be widely used in aviation due to its combination of low weight, resistance to atmospheric corrosion, and when alloyed with another material (e.g. copper), its strength. However, aluminium's highly reactive status means that on submersion, it reacts both with the metals it is alloyed with (causing pitting) and the metals it is physically bonded with (causing galvanic corrosion).
Knowledge on how to halt these processes, both on the seabed and post-recovery, has been steadily increasing since the 1980s, knowledge which enjoys inevitable crossovers with other areas of maritime archaeology covering metal artefacts. A selection of articles on these can be found in the Bibliography.