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ATPL » Air Law – Helicopter » Instrument Approach Procedures

37.94 Approach Procedures

37.94.2 Describe the descent limitations from cruise to approach commencement. AIP GEN



5.1 Minimum Flight Altitude (MFA)

Descent Below MFA 

5.1.8 Descent below MFA prior to arrival may only be commenced in the following circumstances:

  • (a) In accordance with published Enroute descent (Distance) steps, or VORSEC chart steps, or when under radar control; or
  • (b) Prior to the first Distance or VORSEC step when:
    • (i) a positive fix has been established by an unambiguous DME readout for at least 15 seconds, or by use of an off-track VOR or NDB provided the angle of intersection is 45° or greater; and
    • (ii) a positive tracking indication has been received by navigation equipment for at least 15 seconds; and
    • (iii) during descent aircraft navigation equipment is actively monitored to ensure continuity of guidance.
  • (c) Descent is restricted to the higher of MSA, or Volcanic Hazard Zone upper limit, or MOA or Danger Area or Restricted Area upper limit (plus separation buffer if required), and based on an optimum descent gradient of 5% (300 ft/NM) to the first Distance or VORSEC step.
  • (d) Within 10 NM of the aid or fix from which it is intended to conduct an instrument approach, descent is limited to the minimum holding altitude, procedure commencement altitude or MSA, whichever is the higher.
  • (e) Outside controlled airspace the IFR table of cruising levels applies.
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