CDFA – Continous Descent Final Approach

Excerpt from annex VII to ED Decision 2014-016-R (Part-NCO)

  • (a)  Introduction
    1. Controlled flight into terrain (CFIT) is a major hazard in aviation. Most CFIT accidents occur in the final approach segment of non-precision approaches; the use of stabilised-approach criteria on a continuous descent with a constant, predetermined vertical path is seen as a major improvement in safety during the conduct of such approaches. The following techniques are adopted as widely as possible, for all approaches.
    2. The elimination of level flight segments at MDA close to the ground during approaches, and the avoidance of major changes in attitude and power/thrust close to the runway that can destabilise approaches, are seen as ways to reduce operational risks significantly.
    3. The term CDFA has been selected to cover a flight technique for any type of NPA operation.
    4. The advantages of CDFA are as follows:
      • (i)  the technique enhances safe approach operations by the utilisation of standard operating practices;
      • (ii)  the technique is similar to that used when flying an ILS approach, including when executing the missed approach and the associated missed approach procedure manoeuvre;
      • (iii)  the aeroplane attitude may enable better acquisition of visual cues;
      • (iv)  the technique may reduce pilot workload;
      • (v)  the approach profile is fuel efficient;
      • (vi)  the approach profile affords reduced noise levels; and
      • (vii)  the technique affords procedural integration with APV operations.
  • (b)  CDFA
    1. Continuous descent final approach is defined in Annex I to the Regulation on Air operations.
    2. An approach is only suitable for application of a CDFA technique when it is flown along a nominal vertical profile; a nominal vertical profile is not forming part of the approach procedure design, but can be flown as a continuous descent. The nominal vertical profile information may be published or displayed on the approach chart to the pilot by depicting the nominal slope or range/distance vs. height. Approaches with a nominal vertical profile are considered to be:
      • (i)  NDB, NDB/DME (non-directional beacon/distance measuring equipment);
      • (ii)  VOR (VHF omnidirectional radio range), VOR/DME;
      • (iii)  LOC (localiser), LOC/DME;
      • (iv)  VDF (VHF direction finder), SRA (surveillance radar approach); and
      • (v)  GNSS/LNAV (global navigation satellite system/lateral navigation).
    3. Stabilised approach (SAp) is defined in Annex I to the Regulation on Air operations.
      • (i)  The control of the descent path is not the only consideration when using the CDFA technique. Control of the aeroplane’s configuration and energy is also vital to the safe conduct of an approach.
      • (ii)  The control of the flight path, described above as one of the requirements for conducting an SAp, should not be confused with the path requirements for using the CDFA technique.
      • (iii)  The predetermined approach slope requirements for applying the CDFA technique are established by the following:
        1. (A)  the published ‘nominal’ slope information when the approach has a nominal vertical profile; and
        2. (B)  the designated final-approach segment minimum of 3 NM, and maximum, when using timing techniques, of 8 NM.
      • (iv)  An SAp will never have any level segment of flight at DA/H or MDA/H, as applicable. This enhances safety by mandating a prompt missed approach procedure manoeuvre at DA/H or MDA/H.
      • (v)  An approach using the CDFA technique will always be flown as an SAp, since this is a requirement for applying CDFA. However, an SAp does not have to be flown using the CDFA technique, for example a visual approach.