MEL and Dispatch

Can the aircraft leave with this broken? This article maps the ATA-22 chapter of a representative operator's MEL — its structure, its patterns, and its high-consequence items. A sourcing note up front: the MEL is operator-specific and, for the fleet modelled here, a non-English document — everything below is attributed paraphrase of one operator's practice, presented for the patterns rather than the numbers. Your own MEL is the only dispatch authority.

1. Three layers, one referral mechanism

The document works in three layers: ME (MEL entries — a referral table indexed by ECAM alert), MI (MEL items — the actual dispatch conditions: repair interval, number installed/required, placard, and the (o)/(m) marks), and MO (operational procedures — the crew actions the (o) mark points to; (m) marks maintenance procedures). Usage: ECAM fires → look the alert up in ME → follow the referral to the MI item → read the conditions → jump to MO for the procedure.

The referral table's three kinds of answer (paraphrased from the operator's ME chapter):

"Not related to the MEL" does not mean trivial — those are operational alerts (levers out of position, speeds not entered — article 30's TOS family): nothing is broken, fix the operation and they vanish. The three no-dispatch lines are the ground mirror of article 31's harshest airborne cases: what can be endured in the air may not be carried from the ground. Other referrals worth noting: FM 1(2) FAULT refers to the FMGEC item, not an FM item — the ECAM's FM fault is treated as a whole-computer problem.

2. The CAT downgrade ladder

Collating the "maximum landing capability" lines across the MO procedures produces the most-examined table in the chapter (paraphrase):

How to read it: this ladder is the ground edition of article 12's QRH equipment table — airborne, the QRH answers "what remains"; on the ground, the MEL answers "may we go, and with what strings".

3. The RNP AR sensitivity surface

Tallying the restriction lines across the chapter: FMA indications, the APs (one inoperative bars RNP AR below 0.3 and missed approaches below 1 NM; both bar it entirely), the FDs (RNP AR wants both), both takeover buttons, the AP disconnect warning, the APPR pushbutton, the ND mode/range selectors, two MCDUs out, either FM or FMGEC, an expired navigation database — almost every item in the chapter carries an RNP AR line. The mechanism: RNP AR's equipment list (article 34) is the longest on the aircraft — two FMGECs, two MCDUs, two FDs, one or two APs, dual GPS, TAWS, both FCU channels — so any missing part hits it first. The teaching rule: dispatch begins with "can this airframe still fly AR today?" — the answer shapes routing and alternates before anything else.

4. ETOPS and the number-one effect

The items that carry an ETOPS restriction: AP 1 (AP 2 does not!), FM 1 / FMGEC 1 (side 2 does not), MCDU 1 (2 and 3 do not), both FMAs' AP/FD indications, the AP disconnect warning, FM 1-side fuel/time predictions (FM 2's do not) — and both A/THR channels restrict to ETOPS within 180 minutes rather than a full bar. The pattern to learn instead of the list: "ETOPS recognises number one." In the ETOPS configuration the side-1 units carry specific duties (FIDS residence, default mastership, data sources — article 01, article 28); when the first son is sick the family skips the long trip, when the second is, it travels anyway.

5. High-consequence single items

Expired navigation database (the chapter's one A-interval item): dispatch permitted up to ten consecutive calendar days past expiry, on four conditions — use only procedures unchanged by the new cycle; verify database fixes against current charts (coordinates, frequencies, status) and the route's required facilities; and the entire PBN family prohibited (RNP AR/APCH/1/2/4, RNAV 1/2/5/10). The MO adds the disagreement branches: a conventional procedure that no longer matches the chart is flown with manually tuned navaids; changed airway segments are rebuilt by inserting waypoints from current data (article 04's line-by-line logic, in full).

A/THR disconnect warning inoperative — the 15-second procedure. The MO instructs (paraphrase): after engine start, press and hold an autothrust instinctive-disconnect pushbutton for at least 15 seconds; the A/THR remains disconnected for the entire flight; in flight, all A/THR functions — ALPHA FLOOR included — are inoperative. Article 17's "15-second red line" turns out to be a legal, deliberate act here: with the disconnect warning dead, an A/THR that could fail silently is worse than no A/THR at all — a certain nothing beats an uncertain something. (The same procedure applies when both FMAs' A/THR indications are lost.)

APPR pushbutton inoperative: capability capped at CAT 1, and the MO lists the remaining approach menu — NAV/FPA, TRK/FPA, LOC/FPA (when the LOC pushbutton works), and raw-data manual flying (articles 02/12's preview, sourced).

The FMGEC item — chain effects and two MO gems: one FMGEC inoperative means pulling its breaker and treating the same-side FMS, AP and FD all as inoperative (three referrals in one). The MO adds two cold details: for ADS-B/EHS, set the ATC selector to the healthy side (the transponder eats FMGEC data); and FMGEC 1 inoperative with a CONF 3 landing planned: GPWS FLAP MODE pushbutton OFF, and ignore the blue LDG MEMO FLAPS line — the FM-page landing-configuration entry can no longer reach the warning system, which then judges against CONF FULL and would false-alarm a normal CONF 3 landing.

Single FM inoperative — the MO flow: during cockpit preparation, load the flight plan into the failed side's surviving path — select BOTH ON toward the healthy FM to build the plan, then back to NORM; and for oceanic/remote operations, pre-flight-check backup navigation (MENU → NAV B/UP → F-PLN key → verify MCDU and ND → deselect) — article 19's "check B/UP first", as MEL law. If NAV B/UP itself is inoperative, RNAV 10/RNP 4/oceanic RNP 2 are barred.

FCU granular items: the three selector knobs (SPD-MACH, ALT, HDG-TRK), both inner baro knobs, and the takeover buttons' priority function are zero-tolerance — all must work; the V/S-FPA knob is dispatchable (B interval) when not operationally needed; the changeover buttons (HDG-V/S↔TRK-FPA, SPD↔MACH) may fail locked on the basic pair; windows and light bars are dispatchable when the PFD/ND indications back them up. The pattern: "the knobs you twist outrank the buttons you push" — target-value selectors get no relief; mode buttons and lamps are negotiable (article 02).

NAV B/UP as an item: C interval, both sides may be inoperative, unconditionally — but it is the hinge of other items' "if backup navigation is inoperative…" branches: a dead B/UP won't stop you leaving; it will stop you crossing the ocean.

6. The dispatch decision — four steps

① ECAM/defect → the ME referral (screen out the three no-dispatch lines first). ② Read the MI item's four columns (interval / installed / required / placard) and its "provided that" list. ③ Run the three patterns — which CAT grade remains (against article 12's table), is RNP AR still available, does ETOPS hang on it (a number-one part?). ④ Jump to MO for the crew procedure (plan loading, B/UP pre-check, the 15-second disablement, the GPWS setting). Repair-interval shorthand: A = as stated in the item (the database's ten days), B = 3 days, C = 10 days, D = 120 days — the chapter's workhorses are C items, light bars mostly D, the database the lone A. Boundary with the neighbours: the MEL governs leaving with broken parts; the limitations (article 33) govern the healthy system's envelope; the PBN equipment lists (article 34) are the third corner of the triangle.

[!warning]- Four misconceptions this article corrects (1) "Not related to the MEL" flags an operational alert, not a minor one — nothing is broken, so there is nothing to defer; fix the operation. (2) The same part number does not carry the same dispatch weight — ETOPS recognises number one: AP 1/FM 1/MCDU 1 inoperative hang ETOPS restrictions their side-2 twins do not. (3) Holding the instinctive disconnect for 15 seconds is not always an error — with the disconnect warning dead it is the procedure: deliberately trading the whole A/THR (ALPHA FLOOR included) for certainty. (4) FMGEC 1 out changes your GPWS setup for a CONF 3 landing — the warning system defaults to judging against FULL and will false-alarm unless FLAP MODE is off.

Self-test

[!note]- Q1. The three MEL layers and the (o)/(m) marks?

ME: the ECAM-indexed referral table. MI: the dispatch items (intervals, numbers, placards, conditions). MO: the operational procedures that (o) points to; (m) marks maintenance procedures.

[!note]- Q2. The three no-dispatch ECAM alerts — and why is the T.O SPEEDS family "not related to the MEL"?

FCU FAULT, FM 1+2 FAULT, FMGEC VERSIONS DISAGREE. The takeoff-speeds alerts are operational (data not entered, levers misplaced): no equipment is inoperative, so the MEL has nothing to defer.

[!note]- Q3. Capability with one AP, both APs, the A/THR, and the APPR pushbutton out — and both APs' extra string?

One AP: CAT 3 SINGLE. Both APs: CAT 1, plus RVSM prohibited. A/THR: CAT 2. APPR pushbutton: CAT 1.

[!note]- Q4. Four examples of "ETOPS recognises number one" — and the A/THR's ETOPS treatment?

AP 1, FM 1/FMGEC 1, MCDU 1, FM 1-side fuel/time predictions — all hang ETOPS restrictions their side-2 counterparts do not. Both A/THR channels out restricts to ETOPS within 180 minutes rather than a full bar.

[!note]- Q5. The four preconditions of the ten-day database extension — and how is a chart-mismatched conventional procedure flown?

Only unchanged procedures used; fixes verified against current charts; required route facilities checked; all PBN prohibited. A mismatched conventional procedure is flown on manually tuned raw data, with changed airway segments rebuilt from current waypoints.

[!note]- Q6. The MO for a failed A/THR disconnect warning — and why is deliberate disablement safer?

After engine start, hold an instinctive disconnect at least 15 s: the A/THR (ALPHA FLOOR included) stays off for the flight. A silent, unannounced A/THR failure is worse than a known absence — certainty over surprise.

[!note]- Q7. FMGEC 1 out, CONF 3 landing — what changes and why?

GPWS FLAP MODE off, and ignore the blue LDG MEMO FLAPS — the FM's landing-configuration entry no longer reaches the warning system, which would otherwise judge the landing against CONF FULL and false-alarm.

[!note]- Q8. With FM 1 out, the plan-loading switch sequence — and the oceanic pre-check?

BOTH ON toward the healthy FM to load the plan, then back to NORM. Before oceanic/remote flight: pre-check backup navigation (select NAV B/UP, F-PLN key, verify MCDU and ND, deselect) — if B/UP is inoperative, RNAV 10/RNP 4/oceanic RNP 2 are barred.

[!note]- Q9. Which FCU controls are zero-tolerance?

The three selector knobs (SPD-MACH, ALT, HDG-TRK), both inner baro knobs, and the takeover buttons' priority function — all must work; the twistable outrank the pushable.

[!note]- Q10. What does a dead NAV B/UP stop — and not stop?

It does not stop dispatch (C interval, both sides deferrable, unconditional). It stops the ocean: it is the hinge of other items' oceanic/remote branches.

Key takeaways

References

Structure, referral verdicts, item conditions, capability ladders, restriction patterns and operational procedures per one representative operator's MEL, ATA-22 chapter (ME/MI/MO layers) — attributed paraphrase of a non-English operator document; intervals, conditions and procedures vary by operator and airframe, and only your own current MEL is authoritative for dispatch. Cross-references: the airborne capability table in article 12, the limitations in article 33, the PBN equipment lists in article 34, and the mechanism articles linked throughout. The three-question frame and the pattern names are integrative syntheses.

Independent study material, not an Airbus publication and not endorsed by the manufacturer. Always defer to the current operator FCOM, FCTM, and QRH for operational use.