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DWT-HBA Heliport Approach Slope Indicator

  • DWT-HBA Austria
  • DWT-HBA Abmessungen
  • DWT-HBA Photometrie

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HAPI: Visual Approach Slope Indicator for Heliport


Design ensures very good watertightness and protection against corrosion.
Very easy access to all components by removing the cover. Use of dichroic filters with high transmission factor and good thermal resistance. The HBA is fitted with dedicated subassemblies which enable the HBA to automatically switch off when:
1) A misalignment greater than +/- 5° (+/- 30 minutes) is detected.
2) A failure of the flashing mechanism is detected.


  • Very easy site adjustment by using a clinometer (precision 1° minute)
  • Easy maintenance : Replacement of main elements (lamps, front glass, lenses or reflectors) does not require either unit adjustment or any special tools

The DWT-HBA system provides with the necessary visual information to place the helicopter on the ideal approach slope and can be used by day or night.
The system can be used by all helicopters as soon as it has been set up since it does not require any air-borne instrumentation.


Functional Principle DWT-HBA

The HBA is a light box which emits four distinct types of light :
1) Flashing Green Light = Helicopter above the optimal approach slope (too high)
2) Fix Green Light = Helicopter on the slope
3) Fix Red Light = Helicopter slightly below the optimal slope (slightly too low)
4) Flashing Red Light = Helicopter below the optimal slope (too low).


The signal repetition rate of the flashing sectors must be greater than 2 Hz.
In accordance with ICAO recommendations, the HBA (HAPI) shall be capable of adjustment in elevation at any desired angle between 1° and 12 ° above the horizontal with an accuracy of +/- 5 minutes of arc.
The angle size of the Fix Green sector (on the slope) must be 45 minutes of arc.


In compliance with ICAO requirements the HBA (HAPI) must be located adjacent to the nominal lan- ding point and installed in line with the preferred ap- proach direction.
The angle-of-elevation setting of the HBA (HAPI) must be such that during approach when the helicopter pi- lot observes the upper boundary of the „Below Slo- pe“ sector (Fix Red) all objects in the approach area are still cleared by a safe margin.


For detailed technical information please refer to our pdf-datasheet or product catalogue.