Gear Not Down or Not Locked

This is the start of the failure set. A gear that will not extend or lock follows a progressive chain: confirm → gravity extension → (if that fails) an abnormal landing by configuration. This article ties the QRH procedures to the mechanisms learned earlier (gravity extension, doors, NWS, brake degradation).

Note: the procedure detail below is operator/QRH-specific and may not generalise; values follow a representative A330 QRH.

 Gear not down / not locked?
   │
   ├─① Confirm: at least one green triangle on each L/G on the WHEEL SD page? ──yes──► locked! disregard GPWS "TOO LOW GEAR", land normally
   │                                              no
   │                                              ▼
   ├─② L/G GRAVITY EXTENSION:  MAX SPEED 200 kt
   │     GRVTY EXTN → DOWN → wait for downlock → L/G lever DOWN → CHECK GEAR DOWN
   │     consequences: no nosewheel steering · L/G doors stay open
   │     ├─ successful (downlocked) ──► DO NOT RESET the gravity extension → land (no NWS)
   │     └─ unsuccessful ───────────┐
   │                                ▼
   └─③ LANDING WITH ABNORMAL L/G: by configuration
         ├ nose L/G abnormal:    CG aft + KEEP NOSE UP + ENG MASTER OFF before nose impact
         ├ single main abnormal: fuel distribution + keep the affected wing up + ENG MASTER OFF at touchdown (affected side first)
         └ double main abnormal: ENG MASTER OFF during flare + min pitch 6°
         common: A/SKID & NWS OFF · MAX BRAKE 1000 PSI · do not arm autobrake/ground spoilers · no reverse · 500 ft BRACE

1. The first step is always to confirm — the green triangle

The single most important step. A representative QRH carries a caution along these lines:

CAUTION: Do not apply this procedure if at least one green triangle is displayed on each landing gear on the WHEEL SD page. This is sufficient to confirm that the landing gear is downlocked. Disregard any possible GPWS "TOO LOW GEAR" aural alert.

The green triangle (downlock — LGCIU and Position Warning) is the gold standard of downlock. Some part of the indication chain may have failed and the GPWS may call TOO LOW GEAR, but as long as each gear shows a green triangle, it is genuinely locked — do not be led off by a secondary alert, and do not perform an unnecessary gravity extension. This is the discipline of distinguishing a signal from the truth.

2. Gravity extension — 200 kt, NWS and doors do not come back, do not reset if successful

A representative QRH gives:

FOR GRAVITY EXTENSION : MAX SPEED 200 kt / LDG GEAR GRVTY EXTN ... DOWN / When Landing Gear downlocked: L/G lever DOWN, GEAR DOWN indications CHECK / N/W STEERING NOT AVAILABLE / L/G DOORS REMAIN OPEN / If successful: DO NOT RESET LDG GEAR GRVTY EXTN.

Three consequences map to mechanisms learned earlier:

• 200 kt limit — against the 280 kt safety valve of Normal Extension and Retraction: gravity extension relies on gravity and airflow, and too high a speed prevents or damages it, so it is limited to 200 kt.
• NWS not available — gravity extension isolates green hydraulics (Nosewheel Steering: NWS runs on green, isolated after a free-fall), so there is no nosewheel steering; hold direction on landing with differential braking and rudder.
• Doors stay open — gravity extension does not close the doors (Landing Gear Doors); extra drag, no obstacle to landing.
• Do not reset if successful — a reset would try to restore the normal hydraulic path and could unlock an already-extended gear; since downlock succeeded, hold the gravity-extension state to landing.

3. The abnormal-landing common actions — brake to the most-controllable manual mode

Whatever the configuration, the approach brake actions are highly consistent. A representative QRH gives:

A/SKID & N/W STRG ... OFF / MAX BRAKE PR : 1000 PSI / DO NOT ARM AUTOBRAKE / If one or both MAIN L/G abnormal: DO NOT ARM GROUND SPOILERS.

Each maps to an earlier mechanism:

• A/SKID & N/W STRG OFF — enter alternate-without-antiskid (Alternate Braking): in an abnormal configuration the pilot has full manual control of braking.
• MAX BRAKE 1000 PSI — without antiskid, modulate manually at ≤ 1000 PSI to avoid a lock (Alternate Braking / Parking and Ultimate Emergency Braking).
• Do not arm autobrake — autobrake is triggered by the spoilers, and an abnormal configuration should not get automatic heavy braking (Autobrake).
• Main abnormal: do not arm ground spoilers — with a main gear abnormal, the spoilers' lift dump and the resulting automatic braking could worsen an asymmetry or scrape the fuselage; better without.

4. The three configurations

The logic of the three:

• Nose abnormal: the nose wheel must touch last, so move the CG aft and use the elevator to hold the nose up, lowering it gently; shut the engines before the nose strikes the ground (to avoid ingestion/fire).
• Single main abnormal: with one main gear not down, the aircraft will lean to that side — keep the affected wing up to delay contact; shut the affected-side engine first at touchdown (its nacelle will scrape).
• Double main abnormal: with both mains not down, the belly/tail scrapes — hold a minimum 6° pitch (tail touches first, preventing a nose slam) and shut the engines during the flare.

[!warning]- Six misconceptions this article corrects (1) A GPWS TOO LOW GEAR does not mean the gear is unlocked — the green triangle is the gold standard; if it is shown, disregard the GPWS. (2) Nosewheel steering is not available after a gravity extension — green hydraulics is isolated. (3) A successful gravity extension should not be reset — DO NOT RESET, hold it to landing. (4) An abnormal landing does not use autobrake — do not arm it; A/SKID OFF, manual at 1000 PSI. (5) The three configurations are not handled the same — attitude, ENG MASTER OFF timing, and trim all differ (nose CG aft, single main wing-up, double main 6°). (6) An abnormal landing does not use reverse — risk of asymmetry/scrape.

Self-test

[!note]- Q1. How do you confirm downlock, and should a GPWS TOO LOW GEAR alarm you?

At least one green triangle on each landing gear on the WHEEL SD page confirms downlock — that is the gold standard. If it is shown, disregard the GPWS TOO LOW GEAR call: it is a secondary indication and the green triangle is the truth.

[!note]- Q2. What is the gravity-extension speed limit, and what are its three consequences?

200 kt. Nosewheel steering is not available (green isolated), the L/G doors stay open, and a successful gravity extension must not be reset (a reset could unlock an already-extended gear, so hold it to landing).

[!note]- Q3. Why does the abnormal landing use A/SKID OFF + 1000 PSI + no autobrake?

A/SKID OFF drops to alternate-without-antiskid for full manual brake control; without antiskid, manual modulation is kept at or below 1000 PSI to avoid a lock; autobrake is not armed because it is spoiler-triggered and an abnormal configuration should not get automatic heavy braking.

[!note]- Q4. How do the three configurations differ in attitude and ENG MASTER OFF timing?

Nose abnormal: CG aft + keep nose up, engines off before nose impact. Single main abnormal: keep the affected wing up, engines off at touchdown (affected side first). Double main abnormal: minimum 6° pitch, engines off during the flare.

[!note]- Q5. Why is reverse not used?

In an abnormal configuration, reverse risks asymmetry or scraping a nacelle/fuselage, so it is not used.

Key takeaways

References

A330 procedures per a representative operator QRH (L/G GRAVITY EXTENSION — green-triangle confirmation, 200 kt, NWS not available, doors remain open, do not reset if successful; LANDING WITH ABNORMAL L/G — the three configurations, CG aft, fuel distribution, A/SKID OFF + 1000 PSI + no autobrake/spoilers, attitude control, ENG MASTER OFF timing, 500 ft BRACE, no reverse) and FCOM DSC-32-10-30 (the gravity-extension mechanism behind "NWS not available"). The decision chain and three-configuration table are integrative syntheses of the QRH steps; the "why" of each step links to the system articles cited. QRH content is operator/tail-specific — defer to the actual aircraft QRH. The full ECAM L/G warning family is in ECAM Warning Family; the gravity-extension system detail is in Gravity Extension.

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.