High explosive unexploded ordnance neutralization - Tallboy air bomb case study

Abstract

On October 13, 2020, on the fairway connecting the Polish Baltic ports of Świnoujście and Szczecin, an underwater hazardous object of historical origin in the form of the British deep penetration bomb Tallboy dropped during the bombing of the German cruiser "Lützow" in April 1945 was neutralized successfully. It is believed to be the first underwater action concerning this type of bomb, which has previously been neutralized on land in Europe (Germany, one confirmed case). The preparation of the operation, on an unprecedented scale at national, European and global level, took one year and included a series of projects related to clearing the space around the bomb from other identified UXO objects, international consultations, historical analyses, determination of the risk to residents and critical infrastructure in the event of an explosion of the bomb containing approximately 2400 kg of the TORPEX explosive (with an increased force equivalent to almost 3600 kg of TNT). The object was neutralized on spot at the depth of 12 m, near a ferry crossing, by specialists from the 41st Navy EOD Team from the 12th MCM Squadron (8th Coastal Defence Flotilla), using the Low Order Deflagration technique (underwater deflagration method). In the case discussed, there was an accumulation of unfavourable conditions which practically excluded the use of blow-in-situ explosive methods (BIP), as well as the extraction of the object and its transport to a military ground. After a partial deflagration of the explosive, the explosive was detonated (DDT). Estimates indicate that the deflagration level reached between 55 and 60%, which significantly reduced the strength and effects of the underwater explosion.