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Aeroplane Safety: Does Size Matter?

Take-off and landing are high-risk phases of flight and, according to a report by the Airport Cooperative Research Program, most aircraft accidents occur during these manoeuvres. The risk of an aircraft overrunning or undershooting a runway depends on the size and type of the aircraft, but also on other factors, such as aircraft systems failure, ground debris, human error and the weather. At Anderselite, we have a dedicated Aerospace division and during their industry research, they compiled the following findings regarding flight safety…

Size, weight and approach speed
The energy of any aircraft landing, including an emergency crash landing, depends on the size and weight of the aircraft and its approach speed. Under normal circumstances the larger and heavier the aircraft the higher its approach speed, the higher its momentum and the more runway it requires to land and stop.

If a small aircraft experiences total power loss, the pilot can increase the 'braking effect' of drag and slow its approach speed to approximately 40 miles per hour to facilitate a safe landing. If a large aircraft experiences a similar loss, the pilot has no choice other than to attempt an emergency landing at somewhere between 100 and 200 miles per hour and, unless the aircraft is in the vicinity of an airport with a sufficiently long runway, substantial damage to the aircraft may be unavoidable. It is also worth noting that a 10% increase in the gross weight of an aircraft increases the stall speed by 5%.

Aircraft age and maintenance issues
Of course, it does not necessary follow that small aircraft are inherently safer than their larger counterparts. Indeed, large capacity passenger aircraft in the major developed countries of the world are subject to rigorous safety regulations, but smaller capacity passenger aircraft are not necessarily subject to the same regulations.

The chronological age of an aircraft can be a safety issue but with correct maintenance procedures in place, chronological age is less important than the usage rate of the aircraft in terms of pressurisation cycles. Every time an aircraft is pressurised during flight, the fasteners that hold the plates of the fuselage and wings together are stressed and, over time, cracks may develop around the fastener holes due to metal fatigue.

Nevertheless it is the responsibility of the national authority in each country to oversee the continued airworthiness of aircraft registered in that country. A report by the Australian Transport Safety Bureau, for example, highlights the fact that its fleet of piston engine, fixed-wing aircraft, widely used in public transport and charter operations is, on average, 30 years old.

These aircraft are used far less often than their turbofan and turboprop counterparts, engaged in commercial transport operations, but receive correspondingly less continued airworthiness support from the manufacturer. In this situation, their high average chronological age is definitely a safety issue.

Human error
In a discussion of aviation safety it is difficult to underestimate the effects of human error. It is widely accepted that 80% of maintenance errors can be attributed to human factors and, depending upon its magnitude, a maintenance error can lead to an aircraft systems fault or failure and, ultimately, an aviation accident.

Airline pilots are well-trained and typically have the ability to remain calm and take charge in an emergency, but they are human after all. A pertinent, but nonetheless tragic, example of pilot error is that of Air France flight AF447, which plunged into the Atlantic Ocean in June 2009, killing all 228 people on board, despite having fully functional engines. Apparently baffled by frozen airspeed sensors, two inexperienced pilots raised, rather than lowered, the nose of the aircraft, causing an aerodynamic stall and effectively flew the plane into the sea.

A career in the aerospace industry comes with huge responsibility and anyone that underestimates this is ill advised indeed.
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