ATR 42

If a small airliner with its wing on top and a propeller on each side looks a little stubby, you may be looking at an ATR 42. It was the first aircraft ATR built [2], and the ATR 72 is its stretched sibling, with a fuselage 4.5 m longer [14].

The two are so alike that the only external difference between them is size [16]. That makes the 42 one of the harder aircraft to name from a garden. The good news is that there is a reliable trick, and it comes down to counting windows.

Where it came from

ATR began on 4 November 1981 as a joint venture between Aérospatiale of France and Aeritalia of Italy, the companies that later became part of Airbus and Leonardo [2]. The ATR 42 was the partners' first aircraft, and it first flew on 16 August 1984 [2]. It entered service with Air Littoral on 3 December 1985 [3].

Leonardo, the Italian half of the partnership, still builds the fuselages and tail parts in Italy [2].

One name, several generations

The 42 has been through several versions, and air traffic control still tells them apart. The FAA's list of aircraft type designators gives it four codes [1]:

• AT43: the ATR 42-300.
• AT44: the ATR 42-400.
• AT45: the ATR 42-500.
• AT46: the ATR 42-600.

So a flight-tracking app can tell you not only that you are looking at a 42 but which generation it belongs to.

The 42-600

The 42-600 is the newest of the four [1]. ATR announced the first delivery, to Precision Air Services, in a statement from Toulouse dated 9 November 2012 [5].

ATR's factsheet gives the 42-600's length as 22.67 m [4]. The 72-600 is 27.17 m long [15]. Those 4.5 m are the whole of the difference you are trying to see from the ground [14] [16].

Engines have moved on since that first delivery: Pratt & Whitney Canada has had a newer engine, the PW127XT-M, certified to power new-build ATR aircraft [6].

The short-runway 42-600S

For a few years ATR worked on a version of the 42 that could use very short runways. AIN reported in June 2017 that ATR was offering a short take-off and landing version of the 42-600 [7].

The idea, later sold as the 42-600S [8], drew 17 orders from three launch customers [9]. The lessor Elix Aviation Capital was named as one of them on 19 June 2019 [10], and Air Tahiti ordered two [11]. The selling point was runways just 800 m long [21], and ATR's product sheet promised "a shorter runway to wider horizons" [8].

AIN reported on 11 May 2022 that the 42-600S had flown for the first time in a partial configuration [12]. Then, in November 2024, ATR halted development of the short-runway variant to concentrate on its core products [13]. So the 42-600S is a programme that stopped, not a version you should expect to see.

Over Ireland

The 42 has an Irish chapter. In January 2012 Aer Arann painted its first ATR 42 in Aer Lingus Regional colours [18]. For a while, then, an Aer Lingus Regional turboprop over Ireland could be the shorter ATR.

Aer Lingus Regional today is a different story. Emerald Airlines flew its first Aer Lingus Regional route on 26 February 2022 [19], and it flies the bigger ATR 72-600 [20]. Our sources name no airline flying the 42 to Ireland now, so if you see a short ATR overhead, count the windows before you name it.

How to spot one

From the ground the ATR recipe is easy to learn: the wing sits on top of the fuselage, the tailplane sits on top of the fin in a T-tail, and each engine turns a propeller [17]. The main wheels fold into blister fairings low on the fuselage rather than into the engine nacelles [17]. The 42 and the 72 share all of that, because the only external difference between them is size [16].

ATR 42 or ATR 72? This is the hard one. Count the passenger windows behind the wing: the 42 has six on each side and the 72 has ten [16]. If you cannot count them, judge the proportions. With 4.5 m less fuselage [14], a 42 looks short and stocky beside its sibling.

The tracking code settles it when you have one: an ATR 42 shows as AT43, AT44, AT45 or AT46, while the 72's codes are AT72, AT73, AT75 and AT76 [1].

ATR or Dash 8? The De Havilland Canada Dash 8 is the other common regional turboprop. Its main wheels retract into long engine nacelles under the wing, where the ATR's tuck into the fuselage [16] [17]. Close up, the ATR has six cockpit windows where a Bombardier-built Dash 8 has four [16].

ATR or a regional jet? If there are no propellers and the engines hang under a low wing, you are looking at a jet doing a similar job, such as an Embraer E-Jet.

In photographs

Look closer at the shapes, details and liveries. Every photograph links to its original and credits its creator.