Negative ‘g’ forces, though less common than positive ‘g’ forces in typical flight operations, can still be experienced in various scenarios, especially during specific maneuvers or unusual flight conditions. Here are some experiences where negative ‘g’ forces may occur:
Aerobatic Maneuvers: Aerobatic pilots intentionally perform maneuvers that involve negative ‘g’ forces, such as inverted flight, loops with negative ‘g’ segments, and snap rolls. These maneuvers can subject the aircraft and occupants to negative ‘g’ forces, requiring both the aircraft structure and pilot to withstand and manage these forces effectively.
Upset Recovery Training: Pilots undergoing upset recovery training or unusual attitude recovery training may experience negative ‘g’ forces as they recover from extreme flight attitudes. During recovery from an inverted or steeply pitched-down attitude, the aircraft may briefly experience negative ‘g’ forces as it returns to level flight.
Wake Turbulence Encounter: In rare cases, encountering wake turbulence from larger aircraft, especially during approach and landing phases, can induce negative ‘g’ forces as the aircraft is momentarily lifted or disturbed by the turbulent airflow behind the preceding aircraft. This can occur if the aircraft inadvertently flies into the wake vortex of another aircraft.
Stall Recovery: During stall recovery maneuvers, especially if mishandled or if the stall occurs at an unusual attitude, the aircraft may experience negative ‘g’ forces as the pilot applies corrective inputs to recover from the stall and return the aircraft to controlled flight.
Mountain Wave Turbulence: In mountainous regions, particularly near mountain ranges with strong wind patterns, mountain wave turbulence can produce abrupt changes in vertical air movement. Pilots flying through mountain wave conditions may encounter negative ‘g’ forces as the aircraft experiences rapid downdrafts or turbulent airflow associated with the mountain waves.
Certified negative G load limits varies based on categories of aircraft.
Normal Category:
Negative limit load factor: -1.0
Utility Category:
Negative limit load factor: -1.76
Aerobatic Category:
Negative limit load factor: -3.0
