Nonprecision Approaches & CDFA

Lateral guidance only, with no certified glideslope — e.g., VOR, LOC, NDB, LNAV, LOC-BC — and minimums expressed as an MDA.

MDA is a hard floor you may level off at and hold until the runway environment is in sight or you reach the MAP; at a DA you simply begin the go-around at the decision point, accepting a small altitude loss.

Repeated maximum-rate descents and level-offs close to terrain in high-workload, low-visibility conditions produced a long history of CFIT accidents; the Flight Safety Foundation's ALAR work quantified the risk and proposed CDFA.

Flying the final segment from the FAF (or last step-down) in a stabilized, constant-rate descent to about 50 ft above the threshold with only one power/pitch change — no level-off at MDA.

Typically MDA + 50 ft (some use +50 to +100), treated exactly like a DA; the buffer accounts for the sink during a go-around, since you may not descend below MDA without visual reference.

1) Distance FAF to MAP/threshold, 2) altitude to lose (FAF altitude minus TCH-adjusted threshold altitude), 3) required descent gradient/rate (from the plate's gradient and rate-of-descent table).

Groundspeed ÷ 2 × 10 = fpm. 90 kt → 450 fpm; 120 kt → 600 fpm. A 3° path is about 318 ft/NM.

Lose ~1,750 ft over 5.2 NM ≈ 337 ft/NM ≈ 3.2°; at 100 kt (1.67 NM/min) that's about 560 fpm.

Altitude above TDZE ≈ distance × 300 ft — so 3 NM out you should be about 900 ft AGL.

It is advisory only: not obstacle-evaluated below MDA, may not honor step-down fixes in all databases, and baro-VNAV is uncompensated for temperature error. Fly to the MDA/DDA, not the glidepath indication.

No. Honor every step-down fix; if the continuous path would bust one, steepen the earlier segment or fly the step and rejoin the path.

Configured and on speed — gear down, approach flaps, target speed stabilized — so the only change at the FAF is a power reduction to establish the computed descent rate (and starting the timer if the MAP is timed).