Avro Lancaster in the context of "Flight engineer"

Heavy bombers are bomber aircraft capable of delivering the largest payload of air-to-ground weaponry (usually bombs) and longest range (takeoff to landing) of their era. Archetypal heavy bombers have therefore usually been among the largest and most powerful military aircraft at any point in time. In the second half of the 20th century, heavy bombers were largely superseded by strategic bombers, which were often even larger in size, had much longer ranges and were capable of delivering nuclear bombs.

Because of advances in aircraft design and engineering — especially in powerplants and aerodynamics — the size of payloads carried by heavy bombers has increased at rates greater than increases in the size of their airframes. The largest bombers of World War I, the Riesenflugzeuge of Germany, could carry a payload of up to 4,400 pounds (2,000 kg) of bombs; by the latter half of World War II, the Avro Lancaster (introduced in 1942) routinely delivered payloads of 14,000 pounds (6,400 kg) (and sometimes up to 22,000 lb (10,000 kg)) and had a range of 2,530 miles (4,070 km), while the B-29 (1944) delivered payloads in excess of 20,000 pounds (9,100 kg) and had a range of 3,250 miles (5,230 km). By the late 1950s, the jet-powered Boeing B-52 Stratofortress, travelling at speeds of up to 650 miles per hour (1,050 km/h) (more than double that of a Lancaster), could deliver a payload of 70,000 pounds (32,000 kg), over a combat radius of 4,480 miles (7,210 km).

In military aviation, area bombardment or area bombing is a type of aerial bombardment in which bombs are dropped over the general area of a target. The term "area bombing" came into prominence during World War II. Area bombing is a form of strategic bombing. It can serve several intertwined purposes: to disrupt the production of military materiel, to disrupt lines of communications, to divert the enemy's industrial and military resources from the primary battlefield to air defence and infrastructure repair, and to demoralize the enemy's population (see terror bombing).

Carpet bombing, also known as "saturation bombing" and "obliteration bombing," refers to a type of area bombing that aims to effect complete destruction of the target area by exploding bombs in every part of it. The term "area bombing” refers to indiscriminate bombing of an area and also encompasses cases of carpet bombing, including obliteration bombing. It was used in that sense especially during World War II and the Korean War. Area bombing is contrasted with precision bombing. Area bombing is contrasted with precision bombing. The latter is directed at a selected target – not necessarily a small, and not a necessarily tactical target, as it could be an airfield or a factory – and it does not intend to inflict widespread damage.

The Area Bombing Directive was a directive issued by the Air Ministry of the War Cabinet to the Royal Air Force (RAF) during World War II on 14 February 1942. The directive ordered RAF Bomber Command to destroy Nazi Germany's industrial workforce and demoralise the population through area bombing of Germany's cities and their civilian inhabitants.

A twin tail is a type of vertical stabilizer arrangement found on the empennage of some aircraft. Two vertical stabilizers—often smaller on their own than a single conventional tail would be—are mounted at the outside of the aircraft's horizontal stabilizer. This arrangement is also known as an H-tail, as it resembles a capital "H" when viewed from the rear. The twin tail was used on a wide variety of World War II multi-engine designs that saw mass production, especially on the American B-24 Liberator and B-25 Mitchell bombers, the British Avro Lancaster and Handley Page Halifax heavy bombers, and the Soviet Union's Petlyakov Pe-2 attack bomber.

It can be easily confused for the similarly named twin-boom (or "double tail") arrangement, which has two separate tail-booms from the same fuselage rather than a single tail with twin stabilizers (a singular "twin tail" vs. two identical tails).

The Rolls-Royce Merlin is a British liquid-cooled V-12 piston aero engine of 27-litre (1,650 cu in) capacity. Developed as a private venture by Rolls-Royce and first run in 1933, the engine became one of the most successful aircraft engines of World War II, most closely associated with the Hawker Hurricane and Supermarine Spitfire, although the majority of the production run was for the four-engined Avro Lancaster heavy bomber.

Initially known as the PV-12, it was dubbed Merlin after the company convention of naming its four-stroke piston aero engines for birds of prey. The engine benefitted from the racing experiences of precursor engines in the 1930s. After several modifications, the first production variants of the PV-12 were completed in 1936. The first operational aircraft to enter service using the Merlin were the Fairey Battle, Hurricane, and Spitfire. Experience in use led to a series of rapidly applied developments that markedly improved the engine's performance and durability. Starting at 1,000 horsepower (750 kW) for the first production models, most late-war versions produced just under 1,800 horsepower (1,300 kW). The final version, used in the de Havilland Hornet, had over 2,000 horsepower (1,500 kW).

An electronic-warfare aircraft is a military aircraft equipped for electronic warfare (EW), that is, degrading the effectiveness of enemy radar and radio systems by using radar jamming and deception methods.

In 1943, British Avro Lancaster aircraft were equipped with chaff in order to blind enemy air defence radars. They were supplemented by specially-equipped aircraft flown by No. 100 Group RAF, which operated modified Halifaxes, Liberators and Fortresses carrying various jammers such as Carpet, Airborne Cigar, Mandrel, Jostle, and Piperack.