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● RDT COMM ·Patil_Sempai_17 ·July 10, 2026 ·23:16Z

Need help from DPEs to understand what went wrong on my IFR oral

A pilot failed an IFR oral examination after a designated pilot examiner initially offered a single-question test but shifted to a comprehensive line-by-line review of ACS standards before subsequently conducting additional questioning. The examiner cited safety concerns and failed the candidate on two topics: the altitude threshold for descent to 100 feet TCH and the calculation of rate of descent for non-precision approaches, determinations the pilot contested with regulatory references and operational experience. The pilot requested clarification from other examiners regarding the specific deficiencies identified during the evaluation.
Detailed analysis

A Reddit thread describing a failed IFR checkride oral exam has surfaced questions that resonate well beyond the original poster's frustration, touching on fundamental instrument knowledge areas that trip up even experienced pilots. The applicant describes an unconventional oral format—a DPE who initially proposed a single open-ended question tied to the Instrument ACS, then abandoned that approach mid-exam and reverted to traditional line-item questioning after 90 minutes. The disqualifying answers centered on two areas: the applicant's response regarding descent below what they termed "100ft TCH" (threshold crossing height) and their inability to explain rate-of-descent calculation methodology for non-precision approaches. Both are legitimate ACS knowledge elements, and the way the applicant describes their answers suggests genuine gaps rather than DPE unfairness, though the account is one-sided and the DPE's actual reasoning remains unconfirmed.

The two failure points are worth unpacking because they represent recurring weak spots in instrument training nationwide. The first issue conflates two distinct concepts: decision altitude/height (DA/DH) for precision or APV approaches versus minimum descent altitude (MDA) for non-precision approaches, and separately, the touchdown zone elevation (TDZE) plus threshold crossing height used in visual glidepath construction—not a regulatory descent minimum under 14 CFR 91.175. Citing FAR 91.175 without correctly identifying which approach category and which altitude reference applies (DA versus MDA, and the visibility/flight visibility/required references) is a common source of confusion, and DPEs treat this area as safety-critical because misapplying it directly causes CFIT risk. The second issue—rate of descent calculation for non-precision approaches—points to the standard rate-of-descent table (feet per minute based on groundspeed) used to fly a stabilized constant-rate descent from the FAF to MDA, as an alternative to "dive and drive." The applicant's admission that they exclusively fly dive-and-drive, without understanding the constant-descent-angle alternative or how to compute the appropriate FPM using groundspeed tables, is precisely the kind of gap examiners are trained to probe, since FAA guidance (AC 120-108 and the Instrument ACS Task VI) explicitly emphasizes stabilized approach techniques over dive-and-drive as the safer, preferred method.

For working pilots and instructors, this thread is a useful reminder that DA/DH vs. MDA terminology, TCH's actual role in approach design (it is a design parameter for glidepath calculation, not a decision point pilots use in real time), and the rationale behind stabilized non-precision descent techniques are not academic trivia—they are foundational to safe approach execution in actual IMC. Flight instructors preparing IFR applicants should ensure candidates can articulate the difference between precision, APV, and non-precision approach minimums with precision, and can demonstrate—not just recite—how to compute a constant descent rate using a rate-of-descent table or an approach's published descent gradient. DPEs have wide latitude under the ACS to probe scenario-based understanding rather than rote memorization, and this exam format, while stressful, reflects a broader trend in checkride administration toward scenario-based testing (per FAA Order 8900.2 and ACS philosophy) rather than simple question-and-answer recitation.

More broadly, this episode reflects an industry-wide conversation about the erosion of "dive and drive" as a primary non-precision technique in favor of stabilized constant-angle descents, a shift driven by CFIT prevention data and reinforced in both Part 121 SOPs and increasingly in Part 61/141 training. As more non-precision approaches are flown with vertical guidance advisory (LNAV/VNAV, LPV) rendering true "dive and drive" less common in practice, some CFIIs still under-emphasize the classical ROD calculation and DA/MDA distinctions because students rarely fly raw non-precision approaches during training. Examiners, however, are required to test to the full ACS regardless of how modern the training environment has become, and this case illustrates the value of drilling foundational instrument approach theory—not just GPS overlay procedures—well before checkride day, along with rehearsing oral defense of FAR citations in the specific context the examiner is asking about, not just the general regulation.

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