In India, regional aviation is getting ready for take-off. And the only regional aircraft available are turboprops. Regional jets may not be viable here because many far-flung airfields lack the necessary runway length and facilities. Although turboprops are more practical for short flights, it is probably a fact of life that passengers prefer jets.

It is 20 years since the first regional jet entered service. In the late 1980s, Bombardier of Canada was wondering what to do with the Challenger 600 business jet it acquired when it took over Canadair. It eventually opted to create a stretched version, calling it the Canadair Regional Jet (CRJ). The first 50-seat CRJ100 was delivered to launch customer Lufthansa CityLine in October 1992. Other airlines, intrigued by the commercial success of these novel jets, were quick to place orders. Eventually over a thousand CRJ100 and CRJ200 aircraft were built.

A good idea breeds competition and it was not long before Embraer of Brazil came out with the Embraer Regional Jet, the 50-seat ERJ145. Its first delivery to launch customer Continental ExpressJet was in December 1996. This sparked a long-running rivalry between the Bombardier CRJ and the Embraer ERJ, like the Airbus A320 versus Boeing B737 competition, albeit on a much smaller scale. Those were the days when the price of oil hovered around $20 ( Rs. 1,000) per barrel, sometimes even dropping to $10 ( Rs. 500) per barrel. Hence, the relative fuel inefficiency of these regional jets was ignored. Indeed, till a decade or so ago, jets practically seemed set to banish turboprops from the regional market. Embraer stopped manufacturing its 30-seat EMB-120 Brasília turboprop and switched completely to ERJs.

Rising Oil Prices, Growing Jet Sizes

However, all that changed after the 9/11 terror attacks in the United States. With the price of oil threatening to go through the roof, hard questions began to be asked about the economics of regional jets. The tipping point probably came when the price of oil crossed $35 ( Rs. 1,750) a barrel—this made fuel-efficient turboprops rather attractive again. And the only way to keep seat-mile costs on jets under control was to increase the number of seats—first 70, then 90 and then 100. While Bombardier switched to the 70-seat CRJ700, 86-seat CRJ900 and 100-seat CRJ1000, Embraer began producing the E-170 to E-195 variants with maximum seating capacity ranging from 80 to 122. In fact, aviation experts believe that with oil prices ruling high, the 90-seat regional jet is the smallest economically viable unit of production. The Russian Sukhoi SuperJet SSJ 100-95, for instance, which began commercial service in April 2011, takes 98 passengers.

To be fair to regional jets, all regional aircraft are inherently 40-60 per cent less fuel-efficient than standard narrow-body jets like the Boeing B737 and Airbus A320, and the operating costs per passenger can be as much as two to five times higher. However, these stark variations are mainly on account of differences in operation rather than on any technological inadequacy of the regional planes. Why then did regional jets taste instant success? Compared to the lumbering, old-fashioned turboprops, they were faster, more comfortable and had quieter cabins. They could fly considerably longer distances than turboprops and so they became the aircraft of choice on sectors where larger jets had been operating with many empty seats. Passengers preferred jets perceiving them to be safer and more advanced. The airlines could also boast of ‘modern’ all-jet service. And jets needed less maintenance than turboprops—another factor for the increase in jet numbers.

Triumph of the Turboprops

Jets will always be faster than turboprops and cut travel time. But for short flights, say less than 500 nautical miles, the difference in journey time is insignificant while the fuel savings quality of the tardier turboprop becomes paramount. Currently, the only producers of regional turboprops are ATR of France and Bombardier. ATR last year won firm orders for 157 planes and options for another 79—a record. Bombardier’s Q400 isn’t doing half as well, but sales could pick up. In fact, almost 40 per cent of regional aircraft delivered today are turboprops as against only 11 per cent in 2002. And fuel efficiency is the main reason.

The ATR 72 and Bombardier Q400 NextGen burn about two-thirds the fuel of a typical regional jet. They typically cruise at a much lower altitude, so they spend less time on the most fuel-guzzling stage of the journey—the climb to cruise. Their manufacturers claim that these aircraft produce about 50 per cent less CO2 emissions than equivalent modern regional jets and a fraction of that produced by the older jets. With environmental issues increasingly taking centre stage, this is becoming an overriding factor.

Turboprops also are far more efficient than jets at low speed and low level. They need shorter runways than jets—this allows them to operate from smaller, rural airports. They are less susceptible to foreign object damage (FOD), bird strikes and water ingestion. Turboprops are strongly indicated for many remote airports in India where strips are short and conditions challenging. Then why does the average traveller prefer jets? Put it down to so-called “turbo aversion”. Passengers accustomed to earlier generations of turboprops saw them as noisy, uncomfortable, and less safe than jets. This is not a problem in India where turboprops are used to open up new routes and most passengers are not frequent flyers. And although in the popular view, turboprops are more accident prone than jets, this is neither supported technologically nor borne out by accident data.

As for noise and discomfort, manufacturers are continuously striving to improve their planes. Bombardier employs noise-cancellation technology, while ATR electronically synchronises the propellers so as to generate less vibrations. They also reduce noise and vibration by using advanced materials in fuselage and cabin construction, thus making new turboprops significantly quieter than older ones. Turboprops do need more maintenance than jets because of their gearboxes and propeller components. However, advanced engines like the Pratt & Whitney PW127 and PW150 seldom need major maintenance—their health can be assured with little more than oil and filter changes plus scheduled inspections.

Of course, it would be ideal to have a turboprop that emulates a pure jet. Bombardier has attempted just that with its Q400 NextGen. Although the Q400 is of similar weight to the ATR 72-500/600, its engines deliver nearly twice the power of the ATR 72. Translated into performance, the Q400 can cruise comfortably at 360 knots, while the ATR 72 is limited to a cruise speed of 276 knots. Naturally, this enhanced performance means the Q400 consumes up to 30 per cent more fuel than the ATR 72 on the same leg; but it can also carry up to a dozen more passengers. Airlines generally prefer the ATR 72 for short hops while the Q400 is suitable for longer flights as a fuel-saving alternative to regional jets.