Re: Satelitthjelp gir mer Miljøvennlige landinger
Mange "non-presicion" innflyginger (det vil si at det kun er retningsguidance som på en VOR/LOC/NDB/ASR-innflygning, ikke vertikal guidance (glidebane) som på en ILS eller PAR) har publiserte step-down-høyder, og prosedyren var tidligere at når man passerte en høyderestriksjon, så gikk man ned til neste høyde, flatet ut, og fortsatte inn til neste høyderestriksjon, for så å stige ned til neste restriksjon, flate ut osv. Når man kom til minima for apporachen, levlet man av der og kusket innover til man kom til missed approach-punktet. Underveis passerte man gjerne også sitt VDP (Visual Descent Point), som er det stedet (gjerne før MAP) man bør se plassen for å begynne den visuelle nedstigningen til rullebanen med normal vinkel.
SAS og mange andre flyselskaper laget noe som het CANPA (Constant Angle Non-Presicion Approach), på 1990-tallet, mener jeg, for jeg underviste selv i det som en teknikk for militære flyelever rundt 1994/1995. CANPA gikk ut på at man regnet en konstant nedstigningrate (en viss bakkefart tilsvarer en viss nedstigningshastighet, og omtrentlig kan man bruke "(Groundspeed/2) x 10", i synkhastighet. Eksempelvis 160 kts groundspeed (flyhastighet justert for vind) delt på 2, ganger 10, blir 800 fot/minutt descent for en vanlig tre graders glidebane. Man regner slik at idet man kommer til VDP/MAP når man også minima, og slik sett slipper man den gamle, og mer risikable "dive and drive" i lav høyde, og har generelt mer bakkeklaring under mesteparten av innflygingen. I SAS sine kart er det en tabell med anbefalt synkhastighet ifht bakkefart, samt selvfølgelig notert eventuelle "hard altitudes" på veien nedover.
CANPA heter noe annet og mer offisielt nå; og her er litt offisiell info fra ca fem år tilbake:
1.5 The term Continuous Descent Final Approach (CDFA) has been selected to cover
any type of final approach, which is flown in a stabilised manner. It includes precision
approaches as well as APV and non-precision approaches flown as CANPA.
1.6 Non-precision approaches operated other than using a constant pre-determined
vertical path or when the facility requirements and associated conditions do not meet the
conditions specified in paragraph 2.4 are categorised for the purpose of this ACJ as Non-
CDFA, see Terminology below. Such approaches should be classified operationally as special
letdown procedures, since it has been shown that such approaches without additional training
may lead to inappropriate steep descent to the MDH/MDA with continued descent below the
MDH/MDA in an attempt to gain (adequate) visual reference.
1.7 The advantages of flight on a CDFA are:
(a) The technique enhances safe approach operations by the utilisation of standard
operating practises;
(b) Approach profile affords greater obstacle clearance along the final approach course;
(c) Approach technique is similar to ILS techniques, including the missed approach and
the associated go-around manoeuvre;
NPA-OPS 20 ACJ OPS 1.430
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(d) Turbojet aircraft attitude will enable better acquisition of visual cues;
(e) Approach technique reduces pilot workload on turbo jet aeroplanes;
(f) Approach profile is fuel efficient;
(g) Approach profile affords reduced noise levels;
(h) Approach technique affords procedural integration with VNAV approaches;
(i) The CDFA is the safest approach technique for all approach operations.
2. CDFA (Continuous Descent Final Approach)
2.1 Continuous Descent Final Approach. (CDFA) An approach with a predetermined
approach slope that enables a continuous descent to DA/H H or MDA/H . The approach is
flown as a stabilised approach to the DA/H H or MDA/H at or above which the decision to land
or go-around is made. This term includes precision, non-precision approaches (including
CANPA) and approaches with vertical guidance (APV).
2.2 Stabilised Approach. (SAp) An approach which is flown in a stabilised manner in
terms of configuration, energy and control of the flight path from a pre-determined point or
height/altitude.
2.3 CDFA with a designated vertical profile - An approach with a constant, predetermined
approach slope;
(a) The optimum angle for the approach slope is 3 degrees, and the gradient should
preferably not exceed 6.5 percent which equates to 3,77 degrees, (400 ft/NM) for procedures
intended for conventional aeroplane types/ class and/or operations. In any case, conventional
approaches should be limited to 4,5 degrees, which is the upper limit for CDFA per definition
and the upper limit for certification of conventional aeroplanes;
(b) The approach is to be flown utilising operational flight techniques and onboard
navigation system(s) and navigation aids to ensure the approach can be flown on the desired
vertical path and track in a stabilised manner, without significant vertical path changes during
the final segment descent to the runway. Acceptable techniques and/or aids include:
(i) ILS, MLS, GLS, PAR;
(ii) RNAV(VNAV)
(iii) APV
No MAPt is published for these procedures.
2.4 CDFA with a nominal vertical profile - An approach flown to a DA (DH) H or MDA/H
that meets the criteria established in paragraph 2.3 a) above:
(a) The approach should meet at least the following facility requirements and associated
conditions.
NDB, NDB/DME, VOR, VOR/DME, LLZ, LLZ/DME, VDF, SRA, RNAV(LNAV) with a
procedure which fulfils the following criteria:
(i) Final approach track off-set ≤ 5degrees, and
(ii) FAF available, or another appropriate fix where descent is initiated and
(iii) Distance from FAF to THR ≤ 8 NM in the case of timing, or
(iv) Distance to THR information available by FMS/RNAV or-DME; or
(v) Minimum final segment of the designated constant angle approach path should not be
less than 3 NM from the THR unless approved by the Authority.
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(b) The CDFA may also be operated utilising the following techniques:
(i) RNAV(LNAV) with altitude/height cross checks against positions or distances from
threshold (THR);
(ii) Height crosscheck compared with DME distance values.
2.5 Non-CDFA - A non-precision approach flown to a MDA/H that:
(a) Does not meet the criteria established for a CDFA above; and/or
(b) Is operated with step descents and/or with a level segment at MDA/H.
3 Operational Procedures
3.1 A MAPt should be specified for a CDFA with a nominal vertical profile as for any non-
precision approach.
3.2 The flight techniques associated with CDFA employs the use of a predetermined
vertical path. The approach, in addition, is flown in a stabilised manner, in terms of
configuration, energy and control of the flight path. The approach should be flown to a DA/H
or MDA/H at which the decision to land or go-around is made immediately. The approach
technique should be used when conducting:
(a) All non-precision approaches (NPA) meeting the specified CDFA criteria in para 2.4;
and
(b) All approaches categorised as RNAV(VNAV), ILS,MLS, GLS, PAR.
