A318, A319, A320 and A321: Family Differences

The A320 family is the Airbus line of single-aisle twinjets made up of the A318, A319, A320 and A321. The four share a wingspan, a fuselage cross-section, a flight deck and a fly-by-wire flight control system. What changes between them is mainly fuselage length, and with it the weights, the exits and seats, parts of the fuel system and the flap settings with their limit speeds. One EASA type certificate data sheet (TCDS), EASA.A.064, covers all four, and its flight crew data determine the A318, A319 and A321 to be variants of the A320.

For a pilot the family is one aircraft: a single type rating, with differences training rather than a new course between models. This article compares the four from the TCDS (Issue 62), the draft Revision 7 of the FAA Flight Standardization Board (FSB) report and the 2003 JAA Joint Operational Evaluation Board (JOEB) report. Weights and speeds are certified maxima; the weight variant in each Airplane Flight Manual (AFM) decides what applies. The two engine generations are compared in A320neo and A320ceo differences.

One family, one type rating

The FSB report gives the A318, A319, A320 and A321 the type rating designation A-320 and calls them related aircraft on the same type certificate data sheet, FAA TCDS A28NM. Its entry for common type ratings reads "Not applicable". In FAA usage a common type rating joins two separate ratings held on different type certificates, as with the Boeing 777 and 787; the A320 family needs none because its four models already share one rating. The A330 and A340 are related aircraft on other data sheets, at Level E training and checking toward the A320; the A350 is related only for currency.

In Europe the JOEB report, an evaluation by the JAA together with the FAA and Transport Canada dated 21 August 2003, gave all four models a single license endorsement, A318/319/320/321. It found that they had been designed with a very high level of commonality in cockpit layout, in system definition and operation, and in handling characteristics. In 2015 EASA recorded that the report is deemed to be the family's operational suitability data (OSD). It covers the ceo only; the current TCDS names the Airbus document A320 Operational Suitability Data Flight Crew as the approved flight crew data.

"ceo" (current engine option) and "neo" (new engine option) are commercial names; the documents use model numbers. A suffix N marks a neo, NX the A321neo Airbus Cabin Flex (ACF) and NY the A321XLR. The A318 has CFM56-5B engines (A318-111 and -112) or PW6000 engines (-121 and -122); the A319ceo, A320ceo and A321ceo have CFM56 or IAE V2500 engines. The A319neo, A320neo and A321neo, the ACF and XLR included, have the CFM LEAP-1A or the PW1100G-JM; the TCDS lists no neo model of the A318.

Dimensions and seating

The span is common: every model spans 34.10 m with wing-tip fences, and an A319, A320 or A321 spans 35.80 m with sharklets, an option on some ceos. So are the 3.95 m outside fuselage diameter, the 3.70 m cabin width that seats six abreast, the 7.59 m main gear track and the 11.51 m between the engine axes. Fuselage is added or removed both ahead of and behind the wing, and only the part ahead of the wing changes the distance from the nose gear to the main gear.

The 2003 Airbus operator differences tables record the A321's longer wheelbase and the A319's shorter one, with an identical taxi technique. The FCOM puts the runway width needed for a 180° turn on a dry runway, using the recommended technique and with no margin, at about 24 m for the A320 and 30 m for the A321 (see A320 dimensions and ground maneuvering).

The maximum passenger seating capacity (MPSC) in the TCDS is the certified ceiling for each exit arrangement, listed with the minimum number of cabin crew used to show compliance: 3 for the A318 at 136 seats and the A319 at 145, 4 for the A320 at 180 and 5 for the A321 at 220. In the exit codes C is a floor-level Type C door and III a Type III overwing exit. Modifications, such as a second pair of overwing exits on the A319 or over-performing exits, raise the ceilings of the A319, A320 and A321 to 160, 195 and 230. The over-performing exit modifications define a virtual envelope of cabin layouts, not permission to fit the seats: each layout above the original figure needs its own approval (see doors, emergency exits and escape slides).

Weights and fuel capacity

A range means the maximum depends on the model. Each figure tops a set of weight variants: a typical A320ceo variant in the FCOM, for example, has a 77,000 kg MTOW and a 64,500 kg MLW. For straight-in landing minima, the FSB places the A318, A319 and A320 in approach category C and the A321 in C or D, depending on the maximum certificated landing weight of the A321 model. The 2003 JOEB report, under JAR-OPS 1, listed all four in category C for approach and circling. Crews use the category their operator publishes.

The A321 carries slightly less fuel than the shorter models in its wing and center tanks; any more comes from an additional center tank (ACT), an optional tank added to the basic three. On the A320, as the FCOM describes it, an ACT holds 2,992 liters and has no pump: its fuel is pushed into the center tank by pressurizing the ACT with air (A320 fuel system).

The 24,209 liters in the A320 FCOM is the TCDS figure for aircraft with a modification that adds 350 liters to the wing tanks; capacities vary with such modifications.

Speed limits and flap differences

Much is common to every model: VMO 350 kt and MMO 0.82, VLE 280 kt or M 0.67, VLO 250 kt for extension and 220 kt for retraction, and a tire limit speed of 195.5 kt ground speed, the XLR excepted at 204.2 kt. The A319, A320 and A321 share a maximum operating altitude of 39,100 ft, or 39,800 ft with a modification; the A318's basic figure is 39,800 ft, and 41,000 or 41,100 ft apply only to corporate or specially modified aircraft.

The flaps are not common. The angles (slats/flaps, in degrees) and VFEs from the TCDS:

In 1+F the flaps retract automatically at 210 kt, leaving CONF 1; the FCTM notes that on some A321s the 1+F limit is 225 kt (see A320 slats and flaps).

A321 specifics: flaps, fuel and exits

The A321ceo lands with far less flap than its shorter sisters, FULL being 27/25 against 27/35 or 27/40, and from CONF 2 onward its VFEs are higher. Some A321ceos go further: with certain warning and flight augmentation computer standards the CONF 2 limit rises to 215 kt from 205 kt, and some weight variants carry a placard raising CONF 1 to 235 kt and 1+F to 225 kt.

The fuel system is the one A321 item that the FSB's A320-to-A321 table flags as a procedural change, at Level B training and Level A checking. The 2003 Airbus tables describe it: on the A321 the center tank never feeds the engines directly. Two jet pumps and two transfer valves move its fuel to the wing tanks, each engine always draws from its own wing tank, and the A320's wing tank transfer valves are deleted. The fuel panel is otherwise identical, but the center tank pushbuttons read XFR L and XFR R, and the ECAM FUEL page keeps the same philosophy with the design changes shown.

The four pairs of floor-level doors, their slides and their ECAM indications are a B/A item in the FSB table. The A321neo comes in three forms. The plain A321neo keeps the classic layout. The ACF turns the second exit position on each side into overwing exits, one or two a side, relocates door 3, limits the bulk cargo compartment to 800 kg and can carry up to three ACTs, two aft and one forward. The XLR, built on the ACF, adds an integral, inerted rear center tank in the lower fuselage behind the main gear bay, a reinforced main gear with new wheels and tires and extra takeoff-only slat/flap settings (Enhanced Takeoff Configuration, ETOC), whose VFEs are on the PFD and in the AFM, not on the placard.

The XLR also deletes both flight augmentation computers (FACs) and SEC 3 and fits an electrical rudder, so its laws reconfigure differently: NAV ADR 1+2+3 FAULT, NAV ALL SPD UNCERTAIN, and F/CTL SLATS FAULT/LOCKED from the failure of both slat/flap control computers give direct law at once, whatever the landing gear position (see A320 flight control laws and protections).

Differences training between variants

The FSB grades each difference for training and for checking (FSB reports and differences training). Level B training is aided instruction, such as computer-based training (CBT) or a classroom, for systems that work in a similar way but need emphasis. Level A checking means no differences check when the training is done, although the differences may appear in later proficiency checks. Its master differences requirements (MDR) table sets B/A between any two of the A318, A319, A320 and A321, taken from the highest level in the item tables:

• A320 to A319. The emergency exit doors and their ECAM indication are B/A; dimensions, capacities, cargo, weights, center of gravity, maximum altitude, speedbrakes and spoilers are A/A.
• A320 to A321. Fuel tanks and their ECAM indication are B/A with a procedural change, doors and slides B/A, and flaps, speedbrakes and autopilot limitations A/A.
• Engines. The ceo engine controls and indicating, engine start and takeoff thrust setting are B/A. The 2003 Airbus tables add that no engine differences training is needed when the new variant has the engine already known.
• Flight characteristics. No item in the FSB tables for the A318, A319 or A321 is marked as a flight characteristics difference, and none goes above Level B, so none needs simulator training.

The FSB requires no differences checking within the family, with one exception: a note to its MDR table sets Level B checking (B/B) for the move to the A321neo ACF or XLR, even from another A321. A Level B check is an oral or written examination or a CBT self-test. The FSB also accepts currency in any of the four models for all of them.

The JOEB report reaches the same result in European terms, writing its levels as training, checking and currency: B/A/A. Under it:

• an operator flying more than one variant needs approved operator differences requirements (ODR) tables for its fleet; the generic Airbus tables of March 2003 were accepted as one way to comply;
• a type rating course may use any family simulator, followed by a familiarization course on the variant to be flown;
• recurrent training and a proficiency check on one variant are valid for all, provided the differences are covered, and a line check on any variant is valid for all;
• three takeoffs and landings as pilot flying, in any variant or mix of variants, meet the recent experience requirement.

The 2003 tables also find the takeoff tail strike avoidance technique on the other variants the same as on the A320, trained at Level B. For the neo, the ACF and the XLR, which the 2003 report predates, the operator's approved differences program is the reference.

Library articles are written for study and exam preparation. They do not replace your aircraft's approved documentation, your operator's procedures or the regulations themselves.