A320 cruise altitude - conflicting traffic visible through the windshield. Three voices. Three seconds. One correct answer.

By Paul Toensing  |  Custom GPT Solutions  |  May 2026  |  ~8 min read

Three voices, three seconds, one correct answer. Inside what the A320 FCOM and FCTM actually require - and the parts of the procedure most pilots have never had to articulate under examiner pressure.

There is a particular kind of confidence that builds up in a pilot's first few thousand hours. You learn to trust your eyes. You learn that the airplane usually does what you expect. And you learn that when the system says one thing and your training tells you another, your training is usually the safer bet.

TCAS RA compliance is the exception. It is the one situation in which your eyes are the worst instrument in the cockpit, and the published procedure is the only path that preserves the safety solution. This piece is the architectural companion to our AEO Q&A page on TCAS RA - a long-form walk through what the A320 FCOM and FCTM actually say, why each step exists, and where the manual draws lines that most line-pilots have never had to articulate under examiner pressure.

The Three-Voice Problem

Every TCAS RA scenario you will face in a check ride has the same structure. Three voices arrive within three seconds: your visual assessment, the TCAS commanded maneuver, and an ATC instruction that may or may not align with either. The published procedure does not allow you to weight these voices by preference. The order is fixed: follow the RA, advise ATC, then resolve the visual picture if there is one to resolve.

The discrete procedural details - response times, the preventive-versus-corrective distinction, the standard ATC phraseology - are unpacked in the Q&A page. This piece is about the why, and about the parts of the manual procedure that the published LinkedIn article did not have room to address.

The AP/FD TCAS Distinction That Changes the Rule

The most-quoted shorthand for the A320 TCAS RA response is: AP off, both FDs off, fly the green sector. That shorthand is accurate for a specific aircraft configuration - and not quite right for another.

On A320s without the 𝗔𝗣/𝗙𝗗 𝗧𝗖𝗔𝗦 function installed, the shorthand holds. Disconnect the AP, disconnect both FDs (to ensure A/THR is in speed mode and to remove the FD command bars that would otherwise compete with the VSI green sector), and fly the RA manually. On A320s with 𝗔𝗣/𝗙𝗗 𝗧𝗖𝗔𝗦 installed - a function included in the Honeywell TPA-100B Change 7.1 standard on the HKA fleet per FCOM PLP-LOM - the AP status does not change when the RA triggers. The FDs automatically engage if not already engaged, and the AP/FD TCAS guidance provides the vertical commands directly. The pilot's job is to monitor that the V/S stays out of the red area and intervene manually only if the automated guidance is not satisfying the RA.

This is the kind of distinction that surfaces in oral exams and rarely in line operations, and it is one of the reasons examiners ask candidates to specify the aircraft equipment standard before they describe the response.

Why TCAS Goes Quiet Below 1,000 Feet

A pilot once described low-altitude TCAS to me as "the most polite alerting system in aviation - it shuts up exactly when you need it to." That is roughly correct, and it is intentional.

Below 𝟭,𝟬𝟬𝟬 𝗳𝘁 𝗔𝗚𝗟, the A320 automatically reverts to 𝗧𝗔 𝗢𝗡𝗟𝗬 if 𝗧𝗔/𝗥𝗔 was previously selected. All RAs are inhibited and converted into TAs. The system has decided that at this altitude, the terrain is a higher-priority threat than the conflicting traffic. The published inhibition altitudes are more granular than the top-line 1,000 ft rule: RA aural messages are inhibited below 𝟭,𝟭𝟬𝟬 𝗳𝘁 in climb or 𝟵𝟬𝟬 𝗳𝘁 in descent; 𝗗𝗘𝗦𝗖𝗘𝗡𝗗 RAs are inhibited below 𝟭,𝟮𝟬𝟬 𝗳𝘁 in climb or 𝟭,𝟬𝟬𝟬 𝗳𝘁 in descent; 𝗜𝗡𝗖𝗥𝗘𝗔𝗦𝗘 𝗗𝗘𝗦𝗖𝗘𝗡𝗗 below 𝟭,𝟲𝟱𝟬 𝗳𝘁 in climb or 𝟭,𝟰𝟱𝟬 𝗳𝘁 in descent. The system also reverts to TA ONLY whenever a 𝘄𝗶𝗻𝗱𝘀𝗵𝗲𝗮𝗿, 𝘀𝘁𝗮𝗹𝗹, or 𝗚𝗣𝗪𝗦 alert is active.

The operational implication is this: in the terminal area, the system is silent on RAs by design. The crew is expected to integrate visual scanning, ATC instructions, and the absence of an RA-capable system. This is exactly the scenario where pilots are most tempted to assume "if TCAS were going to alert me, it already would have," and that assumption is structurally incorrect below the inhibition threshold.

CLIMB RA During a Go-Around: Both Procedures Apply

This is one of the most useful pieces of the FCOM that almost never appears in informal pilot conversations. If a CLIMB RA triggers during an approach in 𝗖𝗢𝗡𝗙 𝟯 or 𝗙𝗨𝗟𝗟, the procedure is unambiguous: perform a go-around and follow 𝗦𝗥𝗦 orders, while monitoring that the V/S stays out of the red area.

The AP and FD can be kept engaged during the go-around. The SRS manages the climb profile. The VSI confirms separation from the intruder. Both procedures apply simultaneously, and they do not conflict - the SRS will produce a climb attitude that satisfies the RA in almost all geometries. The pilot's job is to recognize that the published procedure is layered, not exclusive, and to intervene only if the automated profile is taking the aircraft toward the red area on the VSI.

NAV TCAS FAULT Is Not NAV TCAS STBY

A common oral exam trap: the candidate is shown an ECAM screen with 𝗡𝗔𝗩 𝗧𝗖𝗔𝗦 𝗙𝗔𝗨𝗟𝗧, and proceeds to describe the procedure for a TCAS in standby mode. They are two different alerts.

𝗡𝗔𝗩 𝗧𝗖𝗔𝗦 𝗙𝗔𝗨𝗟𝗧 triggers when there is an internal failure of the TCAS computer. ECAM STATUS shows 𝗜𝗡𝗢𝗣 𝗦𝗬𝗦 𝗧𝗖𝗔𝗦. The procedure involves advising ATC and reverting to procedural separation, because the system cannot be recovered by mode selection. 𝗡𝗔𝗩 𝗧𝗖𝗔𝗦 𝗦𝗧𝗕𝗬 triggers when the system is in standby - usually because the crew has selected it there. The first step is to verify the mode selection, not to assume the computer has failed.

The two messages share the prefix and the consequence (no RA protection), but they have different causes and different procedures. An examiner who asks about NAV TCAS will frequently follow up with "and how would you know it was the other one" to see if the candidate recognizes the distinction.

The Reporting Obligation Most Pilots Underestimate

HKA OM-A GEN §8.3.7 is unambiguous: an RA shall be reported as an incident by means of an 𝗔𝗦𝗥. Any RA. Not "any RA that produced a significant deviation," not "any RA that ATC asked about," not "any RA where you weren't sure if the maneuver was big enough to matter." The reporting trigger is the RA itself, regardless of the magnitude of the resulting flight path change.

This matters because the safety management system depends on volume to identify trends. An RA that produced a 200-foot deviation is a data point. An RA that produced no deviation at all (because the original flight path was already inside the green area) is still a data point. The system improves with reporting. It does not improve with judgment calls about whether a specific RA was "worth" reporting.