CDA Continuous Descent Approach Pilots view Cpt. Ir. Dirk De Winter EUROCONTROL - Brussels The European Organisation for the Safety of Air Navigation
CDA Pilots Perspective What? CDA is all about the ability to match the optimum descent profile And, after any disruption, rejoin the revised optimal descent profile CDA is an attitude of optimization! While flight safety remains paramount Continuous Descent Approach Pilots view 2
Descend profile: flight idle thrust Continuous Descent Approach Pilots view 3
How to calculate the optimum TOD non-fms aircraft Continuous Descent Approach Pilots view 4
How to calculate the optimum TOD FMS equipped aircraft Airlines use C.I. = 0 high fuel costs low speeds C.I. = 999 high time cost high speeds Typical C.I. value: 12-40 C.I. enables the FMS to calculate ECON CLB,CRZ and DES speeds; and therefore the optimum profile for these speeds Continuous Descent Approach Pilots view 5
A320 Descent Profile (idle thrust) No Wind - ISA - MLW M.80/320kt M.78/300kt M.76/280kt M.74/260 400 350 300 Flight Level ( 100ft) 250 200 150 100 50 M.74/260 reference TOD / fuel used M.76/280 : -05nm / fuel + 20kg M.78/300 : -10nm / fuel + 35kg M.80/320 : -15nm / fuel + 55kg 0 0 20 40 60 80 100 Distance to 3000ft (nm) Continuous Descent Approach Pilots view 6
How FMS calculates the optimum TOD (cste C.I.) altitude Optimum profile no constraint Too early descend FMS optimised Capturing segment (1000 ft/min) B A A B Optimum TOD no constraint Optimum TOD with constraint FL200 FL100 1000ft Appr Config Appr Spd Constraint e.g. below FL200 Capture point 250 kt deceleration FMS calculates backwards from 1000ft Note: Vertical optimisation only when lateral routing available Continuous Descent Approach Pilots view 7
How to manage tactical constraints with FMS Conditional clearance FMS optimised Descend now - FMS Capture mode Descend now non optimised PEPAX e.g. Speedbird 533J when ready descend to FL280 to reach FL280 at PEPAX 90% commercial IFR traffic has basic VNAV functionality 65% commercial IFR traffic has advanced (near-idle profile) VNAV functionality Continuous Descent Approach Pilots view 8
Types of CDA procedures Lateral and vertical path is known FMS optimised FMS optimised until end of arrival ATCo must provide pilot DTG to optimise ROD and configuration Dist (nm) * 3 = Alt (in 100ft) ATCo must provide pilot DTG to optimise ROD and configuration Dist (nm) * 3 = Alt (in 100ft) Continuous Descent Approach Pilots view 9
Do we require a published CDA-procedure to fly a CDA? Track Difference: 35nm Predictability is what we need Continuous Descent Approach Pilots view 10
Is specific CDA phraseology needed? General problem SID/STAR phraseology: Flight crew are uncertain as to whether level restrictions continue to apply or are cancelled when ATC assigns a new level due to inconsistent application of PANS-ATM provisions across States. If on an arrival or transition: DESCEND to FL60 VIA NAMUG 08L PROFILE DESCEND NAMUG 08L FL60 As opposed to OPEN DESCEND NAMUG 08L FL60 UNRESTRICTED DESCEND NAMUG 08L FL60 e.g. LHBP If under radar vectors DESCEND FL60 CONTINUOUS DESCEND FL60 DTG 30NM EXPEDITE DESCEND FL60 Continuous Descent Approach Pilots view 11
Pilot Best Practices for CDO Establish open communication with ATC Closed path FMS route available Insert expected route Insert latest weather Keep FMS updated Open path Radar Vectors X-check alt / DTG Adjust V/S to avoid level flight Use minimum flap setting for requested speed Avoid early gear extension Fly stabilized approach Continuous Descent Approach Pilots view 12
Pilot Best Practices for CDO Ideally CDO from TOD, but we must start somewhere Art of what is possible today Pilots should always aim for CDO Continuous Descent Approach Pilots view 13
CDA benefits - Pilots Predictable flight paths and stabilised approaches; Reduction in pilot workload at critical phase; Reduction in required radio transmissions (closed path design).; Reduction in the incidence of CFIT (closed path design). Continuous Descent Approach Pilots view 14
Summary Questions Suggestions? Continuous Descent Approach Pilots view 15
Continuous Descent Approach Pilots view 16
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Descent profile Continuous Descent Approach Pilots view 18
Descent profile Continuous Descent Approach Pilots view 19
altitude The optimum TOD cste C.I. Cost 20 TOD location
Why to keep high longer? Reduce noise impact Noise reduces exponentially with distance Reduce fuel consumption Continuous Descent Approach Pilots view 21
CDA benefits Aircraft Operators Reduction of Fuel consumption; Increased passenger comfort; Reduction in the incidence of CFIT (closed path design); Authorization of operations where noise limitations would otherwise result in operations being restricted. Continuous Descent Approach Pilots view 22
CDA benefits - General Reduction of Fuel consumption Reduction of atmospheric emissions Reduction of noise Continuous Descent Approach Pilots view 23