Aircraft recovery – from Fraport & Vetter’s perspective

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Hans Hofer, Aircraft Recovery Coordinator for Fraport AG at Frankfurt airport, is considered a specialist in the field of aircraft recovery. He comments on aircraft recovery, how every hour of interrupted operations means incredibly high costs and how Vetter’s products fit into the equation

According to German air traffic licensing regulations (§ 45 LuftVZO), every airport is obliged to uphold conditions for safe operation and to ensure orderly operation. In case of an incident, such as an immobile airplane on the runway, those conditions must be restored as quickly as possible.

In accordance with ICAO annex 14, an emergency plan with appropriate operating procedures for aircraft recovery is additionally recommended. This applies for aircraft both on and in the vicinity of the movement area. Hofer emphasises that the typical characteristics of the airplanes that frequent a particular airport should be taken into account. For this reason, it is essential to name a coordinator responsible for continual monitoring of the plan, how current it is, its functionality and its ultimate implementation. Especially important aspects of preparedness for aircraft recovery include the availability and readiness of special aircraft recovery equipment, 24/365 availability of trained personnel and regular training.

At Frankfurt’s civil airport, special aircraft recovery equipment, such as aircraft lifting bags and other recovery equipment, is constantly available and ready for service. The available tools are capable of gently lifting and, if necessary, removing immobile aircraft, including the A380. “Basically, airplanes are built to fly and have no towing eyes like those on cars”, says Hofer describing the challenges of most aircraft recoveries.  In addition, in the interest of aerodynamics, modern airplanes are increasingly sensitive in design and construction, with the difficulty that one needs special equipment and know-how to avoid further damage and the resulting additional financial losses when recovering an aircraft.

Aircraft lifting bags, such as those offered by the German manufacturer Vetter, are gentle and effective recovery tools and can be used on all types of aircraft; one need only observe the aircraft manufacturer’s requirements, eg regarding placement and maximum permissible contact pressure. An internal weave fabric ensures the tremendous stability of the bags throughout the lifting process. Compared with conventional 0.5-bar lifting bags, Vetter’s innovative 1-bar system also provides an increase of up to 40% in load stability and lateral stability as well as double the nominal lifting power. In addition, the 1-bar system is completely equipped with quick-action couplings for fast and time-saving attachment of all components such as inflation hoses and controllers, making safe and fast recovery possible.

In their basic form, aircraft lifting bags resemble blocks; their support area is parallel to the deployment surface. However, no airplane has flat surfaces on its underside where possible contact points are situated, such as on the fuselage or wings or near the landing gear. The first efforts to safely compensate the gap between lifting bags and aircraft contours using seaweed mats were undertaken in the 1970s, but the demands on contour matching have increased with modern aircraft.

Recognising that “straight and round don’t match” led the engineers at Vetter GmbH to the development of modern contour matching in cooperation with Mr. Klein (Klein-Industrie-Training) and Fraport AG. In addition, serious accidents resulted when lifting bags without contour matching slipped out sideways during lifting, dropping the airplane roughly back to the ground and underscoring the need for new approaches to recovery to improve safety.

Vetter’s contour matching system is based on the principle of the vacuum mattresses commonly used by rescue services. The vacuum chambers form an airtight envelope, which can be uniformly filled with small plastic balls using a filling lance. In this state, the chamber is still mouldable and fills in every cavity or fits to every bump on the support area. Then the air is pumped from the chamber. In the resulting vacuum, the balls are pressed together and the modelled form hardens. This optimal fit to the airplane’s contours prevents point loads and the risk of further damage. The result is nearly complete contact between lifting bag and aircraft, so the highest permissible pressure can be built up in the lifting bag to ensure maximum load stability. The Vetter vacuum chambers are a perfect adaptation of the “straight” lifting bags to the “round” airplane.

According to Hofer, contour matching results in a clear improvement in safety, especially as regards load stability. The lifting power of the lifting bags can be used to its full extent and the danger of damage to both airplane and lifting bags is minimised. Fraport AG has examined and tested various options and alternatives for aircraft recovery. For the record, the result is that there is no better solution than Vetter’s contour matching with vacuum chambers.

Hofer says: “One should never forget that one is using air to lift heavy loads. Just like water, air has no beams or girders, so it must be used with the utmost care, the correct tools and the necessary know-how.”

He says, in most cases it is irresponsible to lift an aircraft without contour matching as the compensation can only be controlled via individual chambers in these cases. Good load stability is not achieved, lifting power is very limited, and the lifting process is very uncertain or nearly impossible. Damage cannot be ruled out and relevant work safety regulations are violated.

Among other services, the aircraft recovery professionals at Fraport AG’s airport fire brigade offer training courses in aircraft recovery, and on request they work with other airports to develop emergency plans that correspond to local circumstances and requirements. They also offer worldwide training on aircraft recovery with various equipment.