Constant Descent Final Approach, CDFA

FAA, NTSB Remain At Odds On ‘Dive And Drive’ Instrument Approaches

Aviation Daily, Apr 7, 2015 by John Croft

To date, the FAA has refused an outright ban on the technique, despite nearly a decade of pressure by the NTSB. A type of non-precision instrument approach composed of a series of step-down altitudes, informally known as “dive and drive,” remains a point of contention between the FAA and NTSB following the August 2013 crash of UPS Flight 1354 in Birmingham, Alabama. UPS separately says it plans to prohibit the practice in its pilot manuals....


Interesting article because it seems that the "Safety" folks at NTSB are at odds with the "Regulators" at FAA. As so often is the case internationally, both are not in agreement with ICAO or EASA. EASA is undergoing a large change from "EU-Ops" to "IR-OPS" in an effort to combine ICAO and national regulations/procedures into one overriding document. Since 2012 EU Implementation Regulations, "IR's" are in effect for both commercial, "CAT" operators and private operators of Non Commercial Aircraft, "NCC" (read: Part 91Ops in a transport category jet).

To see the difference in CDFA operations, take a look EASA's Implementation Regulation, CAT.OP.MPA.115 for "Commercial" operators and you will find that EASA directs that CDFA "SHALL" be used. Reviewing NCC.OP.111 "Private" operators may opt to not use a CDFA. Unlike the requirement to add visibility w/o CDFA found inside the outdated "EU-Ops", "IR-OPS" requires operators NOT using CDFA to not go below the higher of Obstacle Clearance Height, minimums published via a table inside the regulation (i.e. ILS/LPV=200DH) or the Minimum Descent Height if one is published in the AFM.

At this point there is usually a discussion of how much altitude should be added to a DH so as to comply with this IR-OPS requirement. Some guidance can be found from the OEM's and in the case of France, specific guidance based upon the aircraft approach category is directed.

To make the matter more confusing, in 2013 the FAA published an OpsSpec/LOA 073 for operators to use a MDA as a DH (w/o adding to the published minimums) in specific cases and when utilizing the CDFA technique and VNAV guidance. Under certain conditions of electronic glidepath design (RNAV or ILS) or VASI available to a runway, a US operator does not have to add some factor to the MDA when using a CDFA technique. The pilot must still visually avoid the obstacles found below the MDA. Operators previously approved may continue with "Derived Decision Altitude/Height" procedures w/o further action needed.The use of MDA as a DA/DH does not ensure obstacle clearance from the MDA to the landing runway. Operators must see and avoid obstacles between the MDA and the runway when 14 CFR part 91, § 91.175 requirements are met and the approach is continued below the MDA for landing.

This is not what PANS-Ops "Allows" and runs counter to IR-OPS for private operators not using CDFA. In both of these cases, operational criteria direct a "Derived Decision Altitude/Height" by adding some factor to the MDA or DA so as not to descend below it when using a CDFA technique.

Bottomline...

  • 1. If you use CDFA in USA or EU countries, adding some amount to the published mins, and do not go below the published MDA/DA... you might make more missed approaches but will be legal.
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  • 2. If you do not use CDFA in EU countries and territories, their regs require you to not go below the DA and treat it as you would a MDA.