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Use of Radio Altimeter
From SKYbrary Wiki
| Article Information | ||
|---|---|---|
| Category: | Controlled Flight Into Terrain | 
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| Content source: | Flight Safety Foundation | 
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| Content control: | EUROCONTROL | 
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The radio altimeter is an important tool in defence against CFIT, because it provides an independent and unambiguous warning of proximity to the ground, regardless of any navigational uncertainty, or error, e.g. mis-setting of the altimeter sub-scale.
Standard operating procedures should include procedures for the use of the radio altimeter.
Flight Safety Foundation (FSF) Approach-and-landing Accident Reduction (ALAR) Briefing Note 5.2 — Terrain recommends that, "To enhance the flight crew’s terrain awareness, the call “radio altimeter alive” should be made by the first crewmember observing the radio-altimeter activation at 2,500 feet.
"The radio-altimeter indication then should be included in the instrument scan for the remainder of the approach." the briefing note continues.
"Flight crews should call radio-altimeter indications that are below obstacle-clearance requirements during the approach. The radio altimeter indications should not be below the following minimum heights:
- 1,000 feet during arrival until past the intermediate fix, except when being radar-vectored;
- 500 feet when being radar-vectored by ATC or until past the final approach fix (FAF); and,
- 250 feet from the FAF to a point on final approach to the landing runway where the aircraft is in visual conditions and in position for a normal landing, except during Category (CAT) II instrument landing system (ILS) and CAT III ILS approaches.
The briefing note recommends the following cross-check procedures, "used to confirm the barometric-altimeter setting:
- When receiving an altitude clearance, immediately set the assigned altitude in the altitude window (even before readback, if appropriate because of workload);
- Ensure that the selected altitude is cross-checked by the captain and the first officer (e.g., each pilot should announce what he or she heard and then point to the altitude window to confirm that the correct altitude has been selected); and,
- Ensure that the assigned altitude is above the applicable minimum safe altitude."
Further Reading
EASA
- IR-OPS SPA.LVO.100-130 Low Visibility Operations
- AMC & GM SPA.LVO.100-130 Low Visibility Operations
- EU-OPS 1.440 and Appendices to EU-OPS 1.440 and 1.450 deal with Low Visibility Operations.
Flight Safety Foundation
The Flight Safety Foundation ALAR Toolkit provides useful training information and guides to best practice. Copies of the FSF ALAR Toolkit may be ordered from the Flight Safety Foundation ALAR website