Aircraft recovery systems

ADVANCE FLYING ACADEMY

Aircraft recovery systems are designed to ensure the safe recovery of an aircraft in situations where normal flight operations have been compromised, or when the aircraft is unable to maintain control, sustain flight, or safely land using standard procedures. These systems can be employed in a variety of situations such as engine failure, structural damage, or when the aircraft is operating outside its normal flight envelope. Aircraft recovery systems are also used in situations involving extreme conditions, such as during takeoff or landing emergencies.

Here are the main types of aircraft recovery systems:

1. Aircraft Recovery Systems in Emergencies (Crash Recovery Systems)

These systems are used to safely recover an aircraft after it has been damaged, experienced a failure, or encountered an emergency that prevents it from landing safely in the usual manner.

a. Parachute Recovery Systems (Ballistic Parachute Systems)

In some aircraft, particularly smaller general aviation and experimental aircraft, ballistic parachute recovery systems are installed. These systems can help slow down and safely bring an aircraft to the ground in the event of an emergency, such as engine failure or loss of control.

How it works:
- A ballistic parachute is deployed from a capsule mounted in the aircraft’s fuselage or tail.
- A rocket or explosive charge is used to rapidly deploy the parachute, which then slows the descent of the aircraft.
- The aircraft is gradually lowered to the ground, reducing the impact forces on both the occupants and the structure of the aircraft.
Use Cases:
- Small, light aircraft or general aviation aircraft (e.g., Cirrus SR series, which features a whole-aircraft parachute system).

b. Emergency Landing Systems

In certain aircraft, especially military and specialized civilian aircraft, emergency landing systems are used to recover an aircraft that cannot make a normal landing.

Arrestor Gear: Military aircraft, particularly those that operate from aircraft carriers or short runways, often utilize arrestor gear to rapidly decelerate the aircraft.
- Arrestor Hook: A hook mounted on the aircraft tail is engaged with a cable or arrestor wire stretched across the runway. When the aircraft touches down, the hook catches the cable, decelerating the aircraft rapidly.
Drag Chutes: Some military and civilian aircraft use drag chutes that deploy upon landing to help decelerate the aircraft and prevent runway overruns.
Crash Attenuation Seats and Systems: Aircraft recovery systems often include advanced seat designs that are intended to absorb the impact of a crash. These seats, along with crashworthy design principles like energy-absorbing structures, help to protect occupants in emergency landings or crashes.

2. Flight Recovery Systems (for Flight Envelope Protection)

These systems are designed to prevent loss of control or recover the aircraft from an unsafe flight situation, such as stalling or excessive bank angles. This type of system is often part of the aircraft's flight control system and can intervene automatically to recover an aircraft to stable flight.

a. Auto-Trim and Stability Augmentation Systems

Some advanced aircraft, particularly commercial airliners and military planes, use auto-trim systems to maintain stable flight. These systems adjust the aircraft's control surfaces automatically to keep the aircraft flying within its safe envelope.

Stability Augmentation Systems (SAS):
- These systems use sensors to detect any disturbances in the aircraft's flight path, such as unexpected yaw or roll, and automatically correct them.
- It can help recover the aircraft if it experiences uncommanded pitch or roll deviations.

b. Fly-By-Wire Systems (FBW)

On modern airliners and military aircraft, Fly-By-Wire (FBW) systems help manage flight controls electronically, ensuring that the aircraft remains within safe operating limits. The system can intervene automatically when the aircraft approaches dangerous flight conditions, like excessive pitch or roll angles, and will correct the flight path to recover the aircraft.

Envelope Protection: FBW systems are typically programmed with flight envelope protection, preventing the aircraft from exceeding critical parameters like airspeed, altitude, and angle of attack.
Autopilot and Recovery Modes: Many advanced autopilot systems have built-in recovery modes that take over in emergency situations (e.g., if the aircraft stalls or enters a dangerous flight attitude). In these situations, the autopilot may adjust the flight controls to bring the aircraft back to safe flight conditions.

c. Spin Recovery Systems

In aerobatic aircraft, spin recovery systems are specifically designed to recover an aircraft that has entered a spin.

These systems often involve the use of airframe design to help break the spin and recover from a stalled condition. It might include aerodynamic surfaces or automatic flight controls that can adjust the aircraft’s configuration to stop the spin.

3. Recovery Systems for Aircraft with Engine Failure

Engine failure during flight is one of the most common emergency scenarios that can require aircraft recovery systems to bring the aircraft to a safe landing.

a. Gliding Flight Recovery (For Engine-Out Conditions)

When an aircraft suffers engine failure, it may need to perform an emergency glide. The aircraft's glide ratio is the distance it can travel without engine power, which is crucial for engine-out recovery.

Flight Path Optimization: Pilots use flight management systems (FMS) and emergency procedures to optimize glide paths, aiming for the safest landing area, whether it's an airfield, roadway, or open terrain.
Glide Slope Recovery: In some situations, advanced avionics may automatically adjust the flight controls to help optimize the glide path, minimizing altitude loss and maximizing distance.

b. Aero-Towing and Aircraft Recovery from Remote Areas

Some specialized aircraft recovery systems use aero-towing to recover an aircraft that has gone down in remote areas or inaccessible regions. This is common in military or experimental aircraft recovery.

Aero-Towing Procedures: A recovery aircraft may use a tow rope or cable to pull the stranded aircraft back to a suitable landing area, typically when the aircraft is undamaged but cannot take off under its own power.

4. Aircraft Recovery from Water (Amphibious Aircraft Recovery)

For amphibious aircraft or seaplanes, recovery systems are necessary for returning the aircraft to land after a water landing or emergency ditching.

a. Water-Based Aircraft Recovery (Seaplane)

Amphibious aircraft or seaplanes may be equipped with flotation devices or recovery equipment to help the aircraft return to an airfield after an emergency landing in water.

Flotation Devices: These may include emergency floats that can be deployed after a water landing to stabilize the aircraft.
Winch Recovery: Aircraft in the water may be recovered using a winch or crane from the shore or a rescue vessel, especially if the aircraft is small and has no power to taxi back.

5. Aircraft Recovery on Aircraft Carriers

Aircraft recovery on aircraft carriers is a unique case, primarily for military jets. The recovery process must ensure that aircraft can land on the short runways of aircraft carriers, where there’s little space to decelerate.

a. Arrestor Hook System

The arrestor hook system is a vital component of aircraft recovery on aircraft carriers.

Aircraft are equipped with an arrestor hook attached to the rear of the aircraft, which catches an arresting wire stretched across the carrier's landing deck.
Upon touchdown, the hook grabs the wire, rapidly decelerating the aircraft to a safe stop in a short distance.

b. Catapult Launch and Recovery

Launch System: In addition to recovery systems, aircraft carriers also use steam or electromagnetic catapults to launch aircraft quickly.
Landing Assistance: Aircraft on approach use precision landing systems and radar to guide them in for landing, with automated systems controlling the approach.

Conclusion:

Aircraft recovery systems are designed to enhance the safety and operational flexibility of aircraft under a variety of emergency and non-standard flight conditions. These systems include parachutes for emergency recovery, autopilot and fly-by-wire systems for automatic recovery, and emergency landing gear and arrestor systems for short or emergency landings. Each system plays a critical role in ensuring that aircraft can be safely returned to operational status or land safely in challenging situations, improving overall aviation safety.

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