Low-level flying involves air safety hazards such as:
Collision with the ground, electricity wires etc. as a result of pilot error or failure of aircraft systems - at low level and high speed there is little time to react to any problem.
The noise can also disturb animals and hence cause a hazard to horse-riders etc.
By country
Canada
tactical ultra-low-level flight training in Canada is located at CFB Goose Bay in Labrador. In response to lessons learned from the Vietnam War and the growing sophistication of Soviet anti-aircraft radar and surface-to-air missile technology being deployed in Europe, NATO allies began looking at new doctrines in the 1970s–1980s which mandated low-level flight to evade detection. CFB Goose Bay's location in Labrador, with a population of around 30,000 and area of, made it an ideal location for low-level flight training. Labrador's sparse settlement and a local topography similar to parts of the Soviet Union, in addition to proximity to European NATO nations caused CFB Goose Bay to grow and become the primary low-level tactical training area for several NATO air forces during the 1980s. During the 1980s–1990s, CFB Goose Bay hosted permanent detachments from the Royal Air Force, Luftwaffe, Royal Netherlands Air Force, and Aeronautica Militare, in addition to temporary deployments from several other NATO countries. Goose Bay Weapons Range is the only tactical bombing range in eastern Canada. The thirteen million hectare range includes ultra-low-level flying training to 100 feet above ground level, supersonic flight areas, and an inert conventional and precision guided munitions bombing range.
United Kingdom
In the UK, low flying means fixed-wing aircraft at less than 2000 feet from the ground or light propeller driven aircraft and helicopters below 500 feet from the ground. Low flying is permitted across the majority of the UK except for large urban areas, civil airports and some industrial and medical sites. Fixed-wing aircraft can fly down to 250 ft above ground level at a speed of up to 450 kt. Lower height limits apply for helicopters and in certain parts of mid Wales, Northern England and Northern Scotland, designated Tactical Training Areas. See, for example, the Mach Loop in Wales. For safety and to minimise disturbance to the public, military aircrew training at low level is constrained by rules. A specialist military police unit conducts covert monitoring using Skyguard FC radar and investigates alleged infringements.