What phenomenon is referred to as coffin corner?

Coffin corner is a crucial concept in aviation, particularly in the context of flight dynamics. It refers to the narrow band of altitude or airspeed that exists between the aircraft's stall speed and its maximum operating speed (V_max). As an aircraft climbs to a higher altitude, the air becomes less dense, which leads to a decrease in lift generated by the wings. Simultaneously, as speed increases to approach V_max, the risk of exceeding structural limits also rises.

In essence, coffin corner identifies that critical zone where an aircraft can experience dangerous flying conditions. If the pilot inadvertently reduces speed too much, the aircraft risks stalling. Conversely, if speed is increased beyond the maximum limit, there could be a risk of uncontrolled aerodynamic phenomena such as compressibility effects. Therefore, maintaining proper airspeed is vital for safe flight within this confined range.

Other options describe different aspects of flight conditions but do not encapsulate the phenomenon of coffin corner as accurately. The concept of a zone with no lift, for example, does not convey the delicate balance of stall and maximum speeds, while turbulence does not pertain to this specific aspect of flight envelope considerations. The idea of minimized drag also misses the critical relationship between stall speed and operating speed that coffin corner