Wednesday, October 4, 2023

Increasing Situational Awareness & The Certainty Of Mission Success Of The Helicopter Fleet

By Staff Correspondent

Obstacles in the flight path or close to it often pose a threat to helicopters. Such obstacles may be power lines, aerial cableways, pylons and towers. The probability of occurrence of such threats increases during low-level flight manoeuvres. 

Typically, a Standard Helicopter Mission requires alternate routing to counter Enemy Threat to achieve surprises. Further, landing sites may change due to Friendly or Foe activities and poses uncertainty on mission effectiveness. Most of the flight phases may have to be in compromised or Degraded Visual Environment (DVE) limiting mission performance additionally due to atmospheric conditions and AUM of aircraft.

HENSOLDT has situational awareness technologies which help in improving the mission effectiveness of Helicopters i.e. 

  1. LiDAR based Obstacle Avoidance Systems (OAS) 
  2. Synthetic vision & 3D conformal symbology based DVE Technology 

The Equipment’s encompassing above technology may work independently or together based on user specs. 

LiDAR based Obstacle Avoidance Systems (OAS)

The LiDAR based OAS equipment is based on the HENSOLDT patented fibre scanner, leading to a homogeneous scan pattern in the field of view and achieving a detection probability of ≥ 99.5 % within the first second and a detection range of more than 1000 m. The Obstacle Warning System is the result of more than 30 years’ experience in 2D and 3D laser radar system and line scanner technology as well as 15 years background in range data processing and obstacle detection/warning algorithms.

For a reliable CFIT and obstacle strike avoidance for helicopters, it is essential to detect any obstacles at any location within the flight path of the helicopter. Taking into account the above constraints, this can only be done by an on-board real time sensor. The wavelength is the main indicator for the detected size of the obstacles. So the obstacles detectable by a certain wavelength have to be at least as big as the wavelength.

For a laser based OAS using a 1.5 μm laser, obstacles down to 1.5 μm can be detected while a radar based OAS, in case of 94 GHz radar, cannot detect objects smaller than 3 mm. Beyond this, the angular tracking accuracy is directly related to the beam diameter and divergence. The smaller the divergence the better the accuracy and thus it becomes obvious that laser based OAS are capable of resolving much smaller obstacles than radar based OAS. 

Wavelengths in the optical region also show significant advantages in the angular dependency of backscatter. While it is agreed knowledge that radars, including millimetre wave radars, cannot reliably detect wires that are oriented more than 10° to 15° off the perpendicular. On the other hand, LiDAR based OAS systems have proven that wires, independent of their structure or material, can be detected even when flying parallel to the wire.

LiDAR based Obstacle Avoidance system technology offers following unique benefits to its users:

  • Low detectability, high jamming resistance (due to LiDAR) as well as good and flexible HMI. 
  • Maximised safety of the crew, helicopter, passengers and payload during all flight phases due to significantly reduced probability of accidents caused by collision.
  • Considerably reduced workload of the crew during most challenging helicopter operations
  • Mature and proven technology: HENSOLDT experience in providing certified and fully operational system to German Federal, Police, Emergency Medical Service and Royal Thai Air force.

Synthetic vision & 3D conformal symbology based DVE equipment

HENSOLDT Degraded Visual Environment (DVE) Equipment is the pilot assistance system, which ensures safe flights in DVE conditions during all flight phases including take-off, (low-level) flight, approach and landing:

  • During take-off the pilot is supported by 3D outside conformal visual cues displayed on the Helmet Mounted Displays (HMDs) in order to ensure full spatial orientation of the crew.
  • During (Low-Level) Flight the pilots are supported by 3D outside conformal visual cues displayed on the HMDs providing crucial information of the surrounding, i.e. terrain, obstacles and optionally navigation cues (if coupled with a Flight Management System). Furthermore the Advanced Synthetic Vision function displayed on the optional HDD (Head Down Displays) provides a complete situational picture of the surrounding of the helicopter.
  • Approach and landing are supported by providing capabilities for the selection and evaluation of the potential landing zone. The precise landing zone information and a 3D conformal symbology are displayed on the HMD.

With realisation of DVE Technology into the onboard airborne computer, the following advantages could be achieved. 

  • Reduce risk for performed missions, e.g. 
    • Landing in arid regions (brownout) 
    • Flight under VFR in DVE 
    • Low level flight at night (CFIT avoidance) 
    • Landing in confined areas at night etc. 
  • Increase operational availability by allowing missions, which were turned down caused by overall risk assessment, e.g. 
    • Night brownout landing 
    • Night flight in unknown mountainous terrain under DVE 
    • Low level flight in unknown terrain to avoid hostile threats 

The design of the HENSOLDT DVE Equipment is: 

  • State-of-the-art technology 
  • Modular, Scalable and Lightweight. Suitable for accommodating existing and future technologies 
  • Standardised I/O and sensor agnostic design. Ease of integration for new and retrofit platforms. 
  • Modular Data fusion concept capable to work with or without various data/sensor inputs 
  • High Performance certifiable DVE Computer meeting cyber security requirements with the appropriate DAL level 
  • Low latency interface to Heads-Up Display (HUD)
  • Taking into consideration modular and open system design benefits including Future Airborne Capability Environment (FACE) and Joint Common Architecture (JCA) 

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