The threat of drones on the safety of civil aviation
On a warm, sunny mid-June afternoon, about 20 miles out from Logan International Airport and a half-mile in the sky, the pilot of a Jazz airline flight from Montreal on its final approach spotted a red-and-black object. It was a drone, and it was way too close. It missed colliding with the hurtling 50-seat plane by just 25 yards, according to a report filed with the Federal Aviation Administration. Such near-collisions between drones and planes are increasingly common.
1) What is a drone or UAV ?
a) Definition and principles
A drone, or UAV (Unmanned Aerial Vehicle (UAV)), are aircraft able to fly and perform a mission without human presence on board. Flight instruction are given either by a remote control (that can be close to the drone, or thousand kilometres away), or by an electronic system that define the mission to be performed (for example, on small drone, an electronic system instruct the drone to land if the batteries become low). Therefore, there are two types of drones: those who actually require the assistance of a pilot on the ground, and those who are completely autonomous. The flight time autonomy may be extended to the operational decision-making to respond to any random event during the mission.
The principle of UAVs can be compared to that of the model aircraft, where small models are controlled by remote controls. However, piloting a model aircraft requires piloting skills, while those skills are embedded in the drone systems in such a way that a drone operator just has to give simple instruction (climb, descend …).
One may compare UAVs principle to that of missiles. The main difference is that a UAV can be retrieved and re-used, which is not the case for a missile.
Two types of drones
b) Various design
UAVs design is not dictated by the necessity to house at least one pilot. Therefore, multiple possibilities exist to design a drone, and this will depend on the mission to be performed.
During the Vietnam War, Americans have used drones (Firebee) to locate the launching sites of Soviet surface-to-air missiles "SAM-2": 3500 missions were identified. Later, in 1991, during the Gulf War, the USA used drones again (Pioneer) for day/night surveillance, target acquisition and artillery adjustment. British and French began to use the drones at this time.
For their part, the Israelis saturated air defences along the Suez Canal during the Yom Kippur War (1973) with a large number of cheap drones. Later they detected and "lured" by the same means the Syrian anti-aircraft batteries.
Experts believe that drones have really proved their operational capabilities for aerial observation (intelligence) on three major field of operations in former Yugoslavia, Iraq, and Afghanistan.
3) Use of drones
Originally used by the military, drones are now conquering civil field, and are used for multiple applications: dam inspections, harvest optimisation, water rescue operations, aerial photos and videos for movies or documentaries, surveillance of borders, surveillance of forest fires, surveillance of transport networks, parcel delivery, preventive triggering of avalanches, pest and parasite control.
Sea rescue operation with a drone
4) The threat of drones on the safety of civil aviation
a) The consequence of an airborne collision between a drone and an airplane
The consequence of a collision between a drone and an airplane depends mainly on the weight of the drone, the type of airplane, and the zone of impact.
Commercial airplanes are designed to sustain a bird strike. A light drone (although it is hard, not like a bird) would make only light damage to an airliner. The aircraft will have probably to be repaired and checked before the next flight, but the consequence would be only financial.
A heavy drone could have dramatic consequences if it collides with an airliner. Impacting a metallic mass weighting several dozen of pounds at a speed of 150 kts could lead to severe damage and accident. One can easily imagine the consequence if the drone pass through the cockpit windows behind which the pilots are seated.
General aviation aircraft are more exposed to this risk. In addition to the fact that they fly lower (so closer the drones), their light structure could be damaged further to an impact with a drone. Also, as they are often fitted with only one propeller engine, the impact of a drone in the propeller will force the plane to an emergency landing without engine.
Video montage showing the consequence of a collision between a drone and an airplane
b) The regulation
The regulation is defined by each country. In this chapter, we will focus only on the USA and French regulation.
In the USA, since December 21, 2015 the FAA (federal Aviation Administration) requires that that all UAVs weighing more than 250 grams flown for any purpose must be registered with the FAA.
In addition, any business flying drone for work must get an FAA approval.
The rules for operating an unmanned aircraft depend on why you want to fly:
In France, in April 2012, new rules were published by the French government governing the use of airspace by remotely piloted aircraft. It opened a new airspace to drones: the airspace between ground and 150 meters. With the exception of takeoffs and landings, commercial aviation does not use this airspace. Drones are classified according to their weight, and four scenarios are outlined in terms of flight types: in or out of sight of the remote pilot, above or outside populated areas.
Restrictions are added if the drone is flying close to an aerodrome or a helipad. Drones can only fly during the day, and some flights require prior validation from the Authority. In addition, drones operators must be trained adequately.
Most drone flights do not impact on air traffic control Their height and distance from aerodromes/helipads mean they do not interfere with air traffic. They fly without any need to contact a control entity, the remote pilot being solely responsible for safety.
When a flight interferes with departure, arrival or transit trajectories, a memo drawn up by the Air traffic Control is made available to Air Traffic controllers. The remote pilot must then phone the Control Tower to get departure approval. As a drone flight is short, it is easy to find a slot between two traffics.
There are in France specific airspace called ZRTs and R zones that are already mapped and intended for drone operations. The drone operator just has to call the Air Traffic Control to activate these zones for the duration of its flights. These zones become then forbidden to any other civil traffic.
If the pilot of an airliner will be unable to see and avoid a drone, the pilot of a light aircraft flying slower will be more likely to avoid a collision if he is able to see the drone in time, which remains definitely complicated. Whether for an airliner or a private plane, the consequences of a collision with a drone could be hazardous. The penetration of a UAV in a civil airspace without authorization represents a potential threat.
Complying with the regulation allows mitigating this threat. We can count on the professionalism of licensed operators that operate their drones in strict compliance with regulations. But the vast majority of drone’s holders are individuals, of which a substantial part seems to ignore the existence of laws on drones. And then there were deliberate illegal uses (about 80 recorded in France in 2015) which, added to incidents awkward uses, make the issue of security is becoming increasingly urgent.
Reducing the threat of drones over its airspace is an ongoing battle for Civil Aviation Authorities. This work will focus in the future on two areas: the adaptation of the regulations to simplify the industrial use of drones and better manage individual operators, and developing system to detect and neutralize the drones over flying sensitive sites.
Written in August 2016
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