It’s time for another A vs. B comparison. This time around though, it isn’t between Airbus and Boeing, but the world’s two most popular regional turboprop aircraft, the ATR-72 and the Bombardier Q400.

The Indian short haul segment was, and is ruled by the ATR 42 and the ATR 72 turboprop aircraft. A product of the venture between Alenia Aerospace of Italy and European Consortium EADS, the ATR enjoys a monopolistic presence at the small airfields of India, low traffic density routes, or the challenging airfields of the north and the north east. If it’s one aircraft that most airfields know, it’s the ATR 72/42. No other aircraft flies to as many airfields as does this family.

Unsurprisingly, this extremely popular ATR 72 is also the most dreaded amongst the

flying public. The stereotyped image of an aircraft with propellers forces many to raise their eyebrows. But the flights are short and the fares low, making the experience bearable. But to the airlines, its aircraft like the ATR that bring in the money. No wonder that Kingfisher employs 25 ATR 72-500, while Jet flies 20 of the same type. It’s much more economical to operate a turboprop than a jet. Any day.

Not being the first airline in the country that employs aircraft type that are in appearance different from the aircraft type that their airline name suggests, Spicejet is poised to please Bombardier with the gradual introduction of 15 Q400 turboprop aircraft, to fly missions similar to the ATR 72-500. And for the first time in India, the public may in fact be “Proud to fly a turboprop”. With a quiet cabin that is quieter than some jet airplanes, seats that are claimed to be more comfortable, windows that allow for a greater view of the magnificent terrain, huge overhead stowage that can fit your trolley bags, and speeds that lag a jet by only 3-5 minutes on a typical 1 hr route, while being much cheaper than a jet aircraft of comparable capacity, the Q400 will deliver a jet experience at a turboprop’s economics. Poised to revolutionise the experience of short haul flight, are the “DASHing” Q400 NextGens from Bombardier Aerospace.

In this article, focus shall be on the Q400 NextGen, while also fairly comparing the two aircraft that will divide the short haul skies over the Indian subcontinent. Sit back and relax, while we serve you the turboprop of your choice.

Turboprop in India

It was in the October of 1999 when an ATR72-500 was inducted by Jet Airways, marking the dawn of the turboprop era amongst private carriers in India. According to Nikos Kardassis, CEO of Jet Airways, “The turboprop is ideal from a cost perspective to service small feeder routes given the traffic (demand) to capacity (supply) ratios and more importantly for their operational economics. Given this rationale we have felt that the turboprop is ideal for some destinations on our domestic network. These aircraft are especially ideal when it comes to providing air links to smaller towns and cities given that some of the existing airports have only just been remodelled to accommodate such smaller aircraft.” The economics of a turboprop made immediate sense on short haul routes, opening markets previously considered unprofitable to operate on. Air Deccan, which was all about economics, started operations with four ATR 42-500s in the August of 2003. Kingfisher Airlines inducted their first ATR 72-500 in the March of 2006. In a business which promises hairline profits, turboprop aircraft seem to be the only way to open up new markets and still make profit with low load factors. But the subcontinent knew only one manufacturer: ATR.

The need for something better

Kingfisher Airline’s Bangalore-Pune sector has a block time of 1hr 20 minutes when operated by their Airbus A320. The same sector, when operated by their ATR 72-500, takes 2hours. This ATR flight operates at close to midnight, when passenger traffic is low, and speed is of no great concern. But at other times of the day, when demand is high on other short haul sectors, one would foresee the need to introduce an aircraft that can fly a similar number of passengers, with similar operating costs, while generating a higher revenue potential by operating more flights per day. To reword, an aircraft that flies almost as fast as a jet and yet, is as economical as a turboprop: the ideal crossbreed.

The “PropJet”

Considering that Spicejet would like to honour the last three letters in their airline name, the airline placed a firm order for 15 Bombardier Q400s towards the last quarter of 2010, with options on another 15. The Q400 is Bombardier’s answer for a regional turboprop that replaces a jet, while behaving like a jet and yet, significantly reducing aircraft noise and fuel consumption.

The Q400 and the ATR 72 aircraft are both twin engine, turbo prop aircraft capable of carrying around 70 passengers. Both aircraft have a high wing, with six bladed propellers attached to Pratt & Whitney engines on the wing. Both sport a “T” tail, and four abreast seating. The -600 variant of the ATR 72 features a full glass cockpit, much like that on the Q400. This is where the similarities end.

The Q400 is a much longer aircraft, which appears sleeker, with a spine running all the way from the wing box to the rudder. The engines are larger, and extend beyond the trailing edge, unlike the ATR 72 wherein the engine pods taper off under the wing itself. The main landing gear are housed and hinged to the engines, rather than to the belly like in an ATR. The fuselage of the Q400 appears “clean” due to the absence of this belly. The nose of a Q400 is longer and sharper, while that of the ATR is smaller, and blunt. If one were to go by appearances, the Q400’s looks speak of speed, power and aggressiveness. The ATR 72 appears docile. Here are two cases where one may judge books by their covers, and not be disappointed by their true performance characteristics.

To start with, the Q400 and the ATR72-500/600 are similar in weight, but the Q400 is equipped with engines that deliver nearly twice the power of any variant of the ATR 72. The Q400 can cruise comfortably at a max speed of 360kts, while the ATR 72 cruises at a maximum of 276kts. On a sector that takes 2 hours for the ATR 72 to fly, the Q400 can easily fly in under 1 hour 40 minutes, slower than a jet by only around 15 minutes. While the ATR 72 struggles to climb to its service ceiling of 25,000ft (FL250), the Q400 reaches this altitude in minutes. Of course, this performance doesn’t come free: the Q400 can land up consuming nearly 30% more fuel than the ATR 72-500 on the same sector. But attempting to offset the cost of enhanced fuel consumption is its capacity to carry between 6 to 12 more passengers than the ATR 72, at speeds that are jet-like, while consuming much less fuel than a jet of comparable seating capacity.

Designed with the performance of a jet but the technology and economics of a turboprop, the Q400 stands out as a true regional “PropJet”.

Economics

The primary motivation for a scheduled operator, and more importantly a low cost carrier, to invest in an aircraft is the economics that it promises.

The biggest boon to regional turboprop aircraft operators in India is that their turbine fuel is under the declared goods category, attracting a sales tax of only 4% as compared to 28% for other aircraft weighing above 40,000kgs. Topping that is the exemption from landing charges for aircraft with less than 80 seats. Since both aircraft fall into these categories, the economics of a turboprop start making immediate sense.

The average sector distance in the regionally dense portion of India, the south, is 300NM. Considering that at high speed cruise the Q400 takes an average 1hr02min of flying time, and the ATR 72 takes 1hr15min, and that both aircraft start operations at 6:00am local, and wrap up by 11:30pm local, the Q400 can easily fit one extra flight in that 17.5 hour period.

Over and above this, the Q400 that Spicejet will receive will be configured with 78 seats. The ATR 72’s in Jet Airways are configured with 66 seats in some and 68 in the other. In Kingfisher, all the aircraft absorbed from erstwhile Deccan are configured with 72 seats while the rest are configured with 66 seats. As a result, the Q400 lands up with a capacity of 6 to 12 more passengers per flight.

Considering that both airplanes have the same hours in the air, that the Q400’s overpowered engines spend lesser time at a high power to reach cruising altitude, and that the Q400’s engines are not used on ground in the “Hotel” mode like in the ATR, the expected cost of maintenance of both airplanes may be considered similar, though the Q400 has strong reasons to be cheaper to maintain. Landing charges don’t apply to both airplanes, and both airplanes may need two sets of crew to operate the flights in that 17.5 hour period. However, the most significant operational cost, especially in India, is fuel: The Q400’s fuel consumption is nearly 30% more than that of the ATR72 under similar 300NM environmental conditions in high speed cruise.

Bombardier claims that in a European Environment, the 78 seat Q400’s direct operating

costs (DOC) for a 300Nm sector is 8.8% more than that of a 68 seat ATR72-500. ATR on the other hand claims that in the same environment, the DOC for a 300Nm sector for a Q400 is 25% more than the ATR72-500. Considering that Bombardier and ATR are on the extreme ends of the estimating scale, an average of 16.9% reveals that over this 17.5hr period, the Q400 will cost 1.3 times more to operate than the ATR72-500. Considering ATR72 seating capacities of 66, 68 and 72 passengers, the Q400 has 1.31, 1.27, and 1.2 times the revenue generating potential of the ATR72-500 respectively, in the same day. If one were to go by these figures, the Q400 doesn’t do well against a 68 or 72 seat capacity ATR72. In fact, even if one were to consider Bombardier’s figures, and compare them with an ATR72 with 72 seats, the Q400 will only fare as well as the ATR72 (despite the extra flight on the Q400) as far as this conservative, non-operator specific economical comparison is considered.

While available revenue seats, as used in the comparison above, is only indicative of potential, one may appreciate that load factors, which are dependent on seasons, play a big role in profits. The ATR72s in India may break even with a passenger load of around 20-25 passengers. As per Bombardier, considering a low cost carrier’s cost and fare structure, the Q400 in the US and European 300Nm environment breaks even at 45 seats. This means that the Q400 operator must sell significantly more seats per flight just to break even.

Finally, the acquisition price of both aircraft: The Q400 is listed at approximately US$30M, which is US$7M pricier than the US$23 million list price of the ATR 72-600. While these are list prices, usually, the market price is at a discount from the list price which varies based on the aircraft quantity and individual airline negotiation and deals.

Operations

i. Ground handling

The Q400 that Spicejet will receive will have a single class cabin with 78 revenue seats at a 30″ seat pitch; all seats facing forward. With the same comfortable 30″ seat pitch, the ATR72 can seat 72 passengers; However, this will include two rear facing seats, causing significant discomfort and loss of privacy for six passengers.

The Q400 has forward and rear passenger doors on the left, and a service door on the aft right hand side. Passenger boarding is from the front door, and not amongst the chaos of the galley service like in an ATR where both passenger boarding and galley service occur at the aft doors.

The Q400 has significantly larger cargo compartments with significantly larger access doors as compared to the ATR72. The cargo holds are dedicated and not segmented, unlike in an ATR72 where the main cargo hold situated at the forward fuselage is segmented to allow cockpit access. Besides, both cargo sections on a Q400 may be accessed completely from the outside, unlike in the ATR where the rear cargo hold must be accessed from within the cabin. Considering the higher cargo volumetric efficiency, the Q400 has 156% (438ft3) the effective cargo volume of the ATR72 (281ft3).

When it comes to cargo loading, the ATR72’s forward cargo section is easier to load, as the cargo floor is about 1meter high. However, in the Q400, the forward compartment is seldom used for passenger baggage, and the rear cargo hold, which is about 1.5 high, will require the use of a mobile ramp to load cargo, as is done with a European Q400 operator.

Both the ATR 72 and the Q400 can comfortably be turned around in 25 minutes.

ii. Ground Power

The ATR72 has a feature by which the right hand engine may be put in the “Hotel Mode”, wherein the engine is kept running at idle power, but the propellers prevented from rotating by propeller brakes. In this Hotel mode, the ATR72 is supplied with electrics for aircraft power, and pneumatics for air conditioning. Although the concept of saving costs and maintenance time by using a normal engine for ground operation sounds good, it poses some major drawbacks. For one, ground personnel which need access to the right side of the aircraft cannot approach the aircraft when the engine is still running because of the safety hazard involved with a propeller brake that may suddenly give way, and secondly because of the hot gases from the downward pointing exhaust. This prevents aircraft refuelling, while also mandates the service door to be closed. In such a case, the galley needs to be refilled from the passenger entry, leaving the aircraft with only one entrance and exit for the crew, passengers, and service.

Besides, in case of a 10kt tailwind in this “Hotel” mode, a nacelle overheat warning may be generated. For this, the operating manual recommends parking the Aircraft with the nose 45° right to the upwind. However, parking stands do not allow for such flexibility.

Due to these multitude reasons, the crew shut it down 9 times out of 10, leaving the aircraft without any air conditioning or back-up power source (at places where no GPU is available). Only in smaller airports like Aggati where the aircraft is not refuelled and no GPU is available, the Hotel mode is kept running, but the service door closed, making for very uncomfortable operations with just one door.

Secondly, even when the engine is left on, the air conditioning system rarely performs well enough to make any difference in cabin temperature (which has now been bettered in the newer ATR 72s). Thirdly, this results in engine wear and tear.

The Q400 on the other hand, has a dedicated ground power source on board with its APU (Auxiliary Power Unit). The 61kg Hamilton Sundstrand APS 1000 APU provides the aircraft with pneumatics and electric power, but is limited to ground operations only. The advantages are twofold; firstly, the APU may be used anytime, at any airport, without any hazard posed to the ground crew. Secondly, and most importantly, unlike in the ATR, the engine’s life is not affected. A sensor turns off the APU as soon as the aircraft is airborne.

However, the Q400’s source of power on ground also has its share of problems, as around the world, crews had complained about unreliable APUs on board the Q400. After adopting several standard operating procedures regarding APU operation, their reliability has significantly increased, though it does give up once in a while.

Despite using the engine for power, the fuel consumption on the ATR in the Hotel mode is only about 110kg/hr, which is almost the same as the Q400’s fuel burn on the APU (100-150kgs/hr, as observed operationally). However, when the air-conditioning on the ATR doesn’t perform well enough, the crew slightly advance the power levers on the engine, resulting in a fuel burn of about 130kg/hr.

But unsurprisingly, ATR72 or Q400, more often than not a ground power unit is used for the electrics, and an air cart (where available) for air conditioning. This saves on aircraft maintenance, and reduces operating cost by saving on jet fuel.

iii. Flight Ops & Performance. 

The Q400’s PW150A engines, each having nearly twice the power of the PW127M/F engines that the ATR72s come fitted with, have significant implications on the operational planning of flights with this airplane.

The maximum takeoff weight (MTOW) of the Q400’s basic version is nearly 28,000kgs, while that of the ATR72-500 is 22,800kgs, making the MTOW of the Q400 23% more than the ATR72. However, the payload of the Q400, at 8625kg, is only 18% more than the ATR72-500. This discrepancy is attributed to the much higher operating empty weight of the Q400, which is about 17,600kgs, 36% more than that of the ATR72-500. The Q400 has bigger (and consequently heavier) engines, and uses little or no composites in its aircraft structure, unlike the ATR72 which extensively uses proven lightweight composites in the wing, and tail plane.

With the powerful PW150A engines, however, the Q400 has 50% more power per kg of the aircraft at maximum takeoff weight, in comparison to the ATR72-500. This extra power is what determines the terrain surrounded high airfields which the Q400 may be operated to, the cruising speed and consequently the trip time of this overpowered beast.

To start with, the Q400 can take-off and land from airfields that are 10,000ft ASL, while the ATR72-500 is limited to airfields of 8500ft ASL. At sea level, on a 20°C hot day, a fully loaded ATR72-500 clears an obstacle 55ft in height, at a distance of 1000m from the end of the runway, while the Q400 clears a 125ft high obstacle at the same distance, under the same conditions. This tremendous climb performance allows the Q400, at MTOW to reach FL200 in 12 minutes, while the ATR 72 reaches the same altitude in the same conditions in 21 minutes. With both aircraft at 95% MTOW, the Q400 can reach FL250 in 16-18 minutes, while the ATR72, although certified to FL250, just cannot fly to this altitude.

In case of an engine failure, the Q400 can maintain 17,500ft, while the ATR72 with one engine can maintain only 11,000ft. With a 6,500ft margin, the Q400 can be dispatched to regions with significant terrain, clearing obstacles with one engine that the ATR72 simply can’t.

For example, the sector that the ATR72 is deployed on, in Kingfisher: Dharamshala, is surrounded by terrain on all sides, except the south west. The minimum off route altitude (MORA), in the grid in which it is located, is 23,500ft. To the south, the grid MORA is 14,200ft; to the west, the MORA is 16,600ft, while to the south west, the MORA is 3,800ft. Since the Dharamshala flight is based on visual flight rules (VFR), the aircraft is dispatched to this hilly terrain, relying on pilot skill to steer clear of terrain in case of an engine out. Although the standard operating procedures authorizes a go-around, it is next to impossible at this airfield. The Q400, on the other hand, can easily execute a go-around. With a single engine out, the Q400 can easily clear terrain on all 3 of four sides, the 23,500 MORA grid being the only concern.

For other critical airfields, such as Kullu and Shimla, Kingfisher uses its ATR42 aircraft, due to runway length limitations and terrain. The ATR42 has 2,160 shaft horse power (SHP) engines, lending it a power to weight ratio of 0.23SHP/kg at its MTOW of 18,000kg. While this lends the ATR42 a better climb performance than the ATR72, the Q400 still outperforms the ATR42 with 0.33SHP/kg, even if the engines on the ATR42 are upgraded to PW127M.

At sea level, and at MTOW, the ATR42-500 needs 1,165m of runway for takeoff. Under the same conditions, the ATR72-500 needs 1290m of runway for takeoff. The Q400, despite its higher mass, higher payload, and higher take off speeds, needs just 1,300m of runway, or lesser when carrying the same payload as the ATR 72. At certain airfields, such as Shimla, which has a runway length of 1,158m, the Q400 may operate from this runway under reduced load. When taking off from such short airfields with a lower mass, the Q400’s climb performance will be significantly greater.

The Q400’s performance is simply amazing for a regional turboprop; it behaves more like a jet. The aircraft can fly at a maximum true airspeed of 360kts at FL200 (20,000ft above sea level), while the ATR 72 hits its maximum of 276kts at FL170. This speed advantage lends the Q400 tremendous flexibility. As experience with other airlines has shown, the Q400 can fly at its maximum speed when behind schedule, or can fly at a long range cruise speed (consuming significantly lesser fuel) when ahead of schedule. This lends the Q400 greater flexibility than its performance limited European counterpart.

Even the speeds at take off are phenomenal: The ATR 72, on rotation, climbs out at 125kts at MTOW, while the Q400 climbs out at 155kts at MTOW. Upon reaching the acceleration altitude, the Q400 can accelerate to 250kts much sooner.

Both the ATR72 and the Q400 can pull off high performance approach feats: to maintain approach speeds much greater than 200kts till a few miles, and then configure the aircraft for landing. The ATR72-500 can maintain 240kts till 7NM from touchdown; many times, this speed has been maintained till only a few miles before touchdown, and yet fast enough decelerated and configured the aircraft for landing at a speed of 110kts. In this process, turboprop aircraft overtake jets on approach, making jet aircraft the bottleneck in approach scheduling.

The final approach speeds of the Q400 are higher than the ATR72’s: based on weight, and flap setting the speeds vary from 101kts to 129kts. Typically, the Q400 has a final approach speed of 115kts with flaps 35. While the ATR72 falls into a category “B” aircraft based on speeds, the Q400 falls into category “C”. But the approach minima for a category “B” aircraft are lower than a category “C” aircraft, giving the ATR72 the edge over the Q400 in degrading visibility conditions. This can spell the difference between a missed approach and a landing.

With this jet-like performance, the Q400 may be treated as a jet, preventing airport congestion normally attributed to the lack of understanding of a turboprop’s performance by air traffic controllers. For this reason, Bombardier went on a road show in India, educating air traffic controllers of its performance. If the ATC treats this as a jet, (which it should with the ATR as well, at least as far as approach is concerned) , the Q400 can easily fit into jet slots on departures and arrivals, reducing potential delays associated with turboprop aircraft. This can lead to a better on time performance. But how effective the road show has been is to be seen; Kingfisher had tried to get Air Traffic Controllers to fly in the cockpits of ATR72 aircraft to better understand its performance and capabilities, but sadly, that did not work out.

Typical fuel consumption loses the Q400 out to the ATR72. For example, a 296NM mission on an ATR72-500 from Hyderabad to Goa, is planned with a trip fuel of 913kgs, and a flying time of 1hr 14 minutes (74 minutes), at FL180 (near MTOW). A Q400 flying 300NM at FL220 for 1hr 7 minutes (5 minutes slower than otherwise possible), would require about 1,200kgs of trip fuel. For just a gain in 7 minutes over the ATR72, the Q400’s 300kg extra burn isn’t quite appealing. Performance aside, for an ATR72 and a Q400 flying 9 flights a day, the Q400 lands up consuming 985,000kgs extra fuel more than an ATR72, this translating to around INR 4.5Cr in today’s value of ATF for turboprops. While this figure appears big, simple math will show that the 300kgs extra fuel will cost INR 13,800more, translating to each of the 78 passengers paying just INR 180 more per ticket, if only fuel were to be considered. But airline economic models are complex, and vary from airline to airline.

iv. Maintenance & Dispatch Reliability

The Q400 NextGen promises to keep the aircraft more in the air and less in the maintenance hangar, with intervals between checks significantly increased: the “A” check interval has been extended from 400hrs to 600hrs; the “C” check interval has been extended from 4000hrs to 6000hrs. The “A” check interval for the ATR72-500 is 500hrs while the “C” check interval is 5000 hrs. This means that the Q400 NextGen can generate significantly more revenue between checks.

While the Q400 will climb at a very high rate and cruise at 360 knots, Augsburg Airways (which flies under the Lufthansa Banner) flies at reduced power settings to prolong engine life. The crew climb the aircraft at 850 rpm instead of 900, cruise at 850 rpm, and never exceed an interstage turbine temperature (ITT) of 670°C while the maximum is 800°C. This results in a climb rate of between 1,800 and 2,500 feet per minute, which provides a comfortable cabin attitude for the passengers. Cruise is at 345 knots instead of 360. Such engine handling has allowed Augsburg to extend the life of the Pratt & Whitney PW150A engines on the Q400. The prolonging of engine life is not possible on the ATR72-500/600, as the significantly lower powered engines need to be run at higher power settings.

The Q400 has a 99.4% average dispatch reliability, and this figure somewhat surprises Bombardier. “The amazing thing is that we haven’t made structural changes in the basic design of the aircraft; yet the dispatch reliability is a lot better, probably due to availability of inventory, skilled personnel, and accumulation of valuable experience leading to better training and understanding of the airplane.”, says Sunder Venkat, director, sales (Asia) at Bombardier Aerospace. ATR claims the dispatch reliability of the ATR72-500 to be over 99%, making both airplanes almost equally reliable for dispatch.

Passenger Comfort

The toughest impression to erase from the minds of the travelling public is the twisted view on any airplane that has propeller blades. The propeller diameter on the Q400 is 13.5ft, while the fan diameter of the largest jet engine in aviation history, the GE90 engines that power the Boeing 777, is only 10.7ft.

Such dimensions don’t miss the eye, and in the eye of most, any prop is a loud flying machine employing old technology. The Q400 has two Pratt and Whitney PW150A turboprop engines that drive the six bladed Dowty (now part of GE Aviation) propellers. A turboprop engine in essence is a jet engine with a gearbox to increase the torque (the turning force) on the shaft which finally drives the propellers; this increased torque available at the expense of the shaft speed.

But a slower shaft implies slower propellers, and anything that moves slower through the air produces significantly lesser noise. Yet there will be vibration and noise from the engines and the non shrouded propeller, but when comparing the noise in the cabin of a Q400 or an ATR72-500 with the cabin noise experienced in the Boeing 747-400’s upper deck, it’s the mentioned turboprops that stand quieter. Even the noise pollution experienced around the airport from these turboprops is far lesser than most commercial jets.

As the propellers turn on the Q400’s engines, they push air up against the fuselage. This phenomenon causes the fuselage to experience some flexing which can result in unwanted noise and vibration. The Q400 has engines that deliver nearly twice the power of the PW127M/F engines that are fitted onto the ATR72-500. As a result, there is bound to be more noise and vibration in the cabin. Bombardier got innovative, and employed a Active Noise and Vibration Suppression (ANVS) system based on technology that was patented around the 1950s to reduce noise in aircraft cockpits. Through the strategic placement of over 40 microphones, the ANVS system measures these vibration frequencies throughout the cabin. This frequency is analyzed and an equal frequency 180 degrees out of phase is sent to Actively Tuned Vibration Absorbers (ATVAs). The ATVAs, placed between the exterior and interior walls, push back against this vibration with the out-of-phase frequency to effectively “cancel” the vibration. Since the vibration is cancelled, noise generation is also eliminated right at the source. This system results in a cabin that is up to 28dB quieter than otherwise. In addition, passive noise dampeners, as used in the ATR72-500, help reduce low frequency noise and vibration.

The Q400 NextGen is the only commercial turboprop available today to make use of the (ANVS) system, with which the average cabin noise of 77-79dBA is lower than that in an Airbus A318/319, and around 2-4dB quieter than the ATR72’s cabin. Although a noise difference of around 2-4dB is barely perceivable to the human ear, Bombardier states that based on European working standards measurements, this lower noise cuts passenger fatigue by one third.

Any aircraft is at its loudest in the take-off and climb phases. The Q400 reaches the same cruise altitude as the ATR72 in around half the time, giving its passengers further respite from noise much sooner.

The Q400 can, in all conditions, easily reach FL250 (25,000ft), while the ATR72-500 cannot easily reach this altitude in most conditions. The result is the Q400 clearing more weather than the ATR72, allowing for a smoother, less turbulent ride.

Other changes made to the Q400NextGen cabin are mostly cosmetic in nature, such as LED lighting, larger bins, and dished sidewalls; most of which are of no consequence to an economically sensitive passenger of a low cost carrier.

Safety

A sticky issue for the Q400’s reputation is the series of main landing gear accidents in 2007 that plagued the Q400 fleet of Scandinavian Airlines, the flag carrier of Denmark, Norway and Sweden. Within a span of 3 days, two Q400s suffered accidents due to the right main landing gear collapsing. In the very next month, another Q400 suffered an accident with the collapse of the right main landing gear. The very next day, SAS decided to immediately discontinue the use of the Q400.

Within the same period, an Augsburg Q400 returned to Munich after the nose gear did not extend, and landed with the nose gear up.

The first two SAS accidents were related to severe corrosion in the main landing gear, while the third accident was related to a blocked orifice within the actuator assembly which prevented the complete extension of the right main landing gear. The Augsburg accident was due to a the corrosion of a spring.

But this was not all. An All Nippon Airways (ANA) Q400 landed at Kochi, Japan, with a the nose gear retracted. This led Bombardier to advise all Q400 operators around the world to inspect the aircraft’s front landing gear door mechanism. A Porter Airline’s Q400 had to return shortly after takeoff from Montreal’s Trudeau Airport when the landing gear failed to retract after takeoff. In another Porter Airline’s incident, the landing gear would not extend the normal way, and had to be lowered using the alternate mechanism. In two other SAS incidents, the landing gear failed to retract after takeoff.

All the above incidents, with the exception of one in the December of 2006, occurred in 2007.

But the signs of an impending accident were present, and an early flag was raised by Japan’s Civil Aviation Bureau (JCAB) in 2006 itself. JCAB had asked Bombardier to improve the reliability of the Q400s, following 52 cases where Q400s had declared emergencies or had to return to departure airports. Following the accidents involving the SAS Q400s, the Accident Investigation Board of Denmark recommended reviewing the design, the certification and the maintenance program of the Main Landing Gear retraction/extension actuator and rod end. In 2008, the FAA proposed an Airworthiness Directive that mandated incorporation of new weight-on-wheels (WOW) and steering harnesses that have a new conduit construction. The Q400’s reputation for safety was literally on shaky legs.

Bombardier introduced modifications to the in-service fleet following the SAS incidents. These modifications have been incorporated in the Q400 NextGen aircraft, including a new metallurgy applied to the actuator piston and rod in the main landing gear.

Bombardier states that the landing gear has been modified “to overcome even potential maintenance issues”. Since the modifications, there have been no issues with the Q400’s landing gear.

In all of these incidents and accidents attributed to system error, not a single life has been lost. On the other hand, the ATR 72-212 (the predecessor to the ATR 72-500, though no major differences lie in the two types), has taken away 136 lives in two accidents spaced 16 years apart; both accidents a result of the same issue: icing on the wing leading to loss of control. The ATR 72-500 has been suitably modified to better handle icing, and has a clean safety record.

Another situation that could lead to a partial or full loss of control could be a control surface jam. Both the ATR72 and the Q400 have a provision to disconnect the otherwise linked elevators, allowing for the captain or the first officer to have full authority over their respective, independent elevators. But in case of a control wheel (yoke) jam, ATR pilots have to do with nothing but the rudder and power levers to change the aircraft’s heading. Pilots who experience this during training find it very hard to control the aircraft. The Q400, on the other hand, can disconnect the captain’s controls from the first officer’s, allowing the captain to control the hydraulically operated roll spoilers, and the first officer to control the mechanically linked ailerons. Whichever gets stuck, allows for the other to be used.

The main landing gear for the Q400 extend from the engine pods, giving it a wheel base of 8.8meters. The ATR72, however, has the landing gear extending from under the belly, giving it a wheel base of only 4.10 meters, less than half that of the Q400. As a result, the Q400 on the ground is far more stable than the ATR72, in all conditions.

The Pratt and Whitney PW150A is a dependable engine, with the engine as such never giving any problem. In flight shutdowns, though rare, are usually precautionary in nature, and are linked to a malfunctioning Propeller Electronic Control. Precautionary shut downs, when necessary, are seen in the ATR 72’s PW127 engines as well.

But when an engine fails, the Q400, with the remaining engine, can climb at nearly double the rate of an ATR72-500 under similar conditions. Besides, the single engine ceiling of the Q400 is 6,500ft more, making the Q400 far safer, and more dependable in hilly terrain.

The Q400 has one dedicated type II/III emergency exit on the forward right, and three Type I doors. The ATR 72 on the other hand has two plug emergency Type III exits, in addition to two Type I doors. Type II exits are at minimum 20% bigger than Type III exits, and are at floor level, unlike Type III which can be as high as 20 inches above floor level. In case of an emergency, evacuation through one Type II/III and one Type I exit, like in the Q400 (one side evacuation) is potentially much faster than through one Type III and one Type I exit (like in the ATR).

Aircraft Handling and Other Systems

Ask any Q400 pilot who has flown both jets and turboprop, and he will hands down cite his love for the “Propjet” hybrid.

Infact, the aircraft’s engines are so powerful, and the Q400’s aerodynamics so favourable that it holds three records for climbs to 29,527 ft, as submitted to the Fédération Aéronautique Internationale. In the C1i (16,000kgs – 20,000kg) category, the Q400 holds the record at 07:02 minutes, 59 seconds faster than the Saab 2000. In the C1j category (20,000 kg to 25,000kg), the Q400 holds the record at 08:21 minutes, 03:04 minutes faster than the GrummanE2C Hawkeye. In the C1k category (25,000kg to 35,000 kg), the Q400 climbs in 11:41minutes, with no aircraft holding a previous record. The Q400 is undoubtedly the fastest amongst regional turboprop aircraft.

According to Mark Brouwer, a first officer on the Q400 at Augsburg Airways, a regional airline based in Germany, “When the Q400 is light it’s almost as nimble as a small General Aviation aircraft (such as a C152), and is a dream to fly. The climb performance on take off with a light Dash is just insane: on a ferry flight, with normal take off power (90%) in standard conditions, flaps 5, speed V2 + 10 (around 140-145kt), the Q400 will gladly take you to the skies at just under 5000 fpm with a pitch of around 27-28 degrees. When quickly reducing power during cruise the propellers will immediately move into shallow pitch, causing so much drag from the twelve R408 propeller blades that you can feel yourself getting gently pushed forward as the aircraft decelerates. Landing an aircraft with these characteristics (and where 1% change in power makes quite a difference when there’s just over 5000 shp per engine behind it) can be a great challenge, but that makes it all the more fun.

A heavy Q400 will feel a lot more sluggish, maybe even jet-like due to its sleek profile. All V-speeds are greatly increased, and the reason why Bombardier decided to use such powerful engines becomes quite apparent, as the expected initial climb rate in aforementioned conditions is reduced to around 1700 fpm.”

Hydraulic controls are necessary for such a long aircraft, and with the exception of the ailerons, all primary and secondary flight controls are hydraulically powered. The ATR 72 has hydraulics powering only the roll spoilers and flaps, which can make flying the ATR physically more demanding.

In both aircraft, flaps are hydraulically powered, though the Q400 offers 0°, 5°, 10°, 15°, 35° of flap positions, while the ATR72 offers 0°, 15°, 30°. Since extending flaps affects aircraft pitch, automatic pitch trim for flap positions between 15° and 35° reduces the pitch forces felt on the control columns.

Being a long aircraft, the Q400 is very sensitive in yaw and pitch. “A minor annoyance when flying the Q400 is that the Yaw Damper has only limited governance over the rudder, which means that the rudder has to be trimmed manually on every change in aircraft pitch or engine power setting”, says Mark. This problem, although present on the ATR 72, is not as severe.

The Q400’s flight deck sports large LCD screens, which offer considerable advantages on many different levels. “The Q400 can be quite pitch sensitive, so having a large AI (Attitude Indicator) , his on the primary screen really helps when flying manually. The secondary screens can be used both for navigation (NAV mode, in three different formats) and systems monitoring (SYS mode – electrical, doors, fuel, engines) which make monitoring the aircraft both in-flight and on-ground a breeze. The Engine Display is, just like the other displays, clean and uncluttered, allowing us to detect and analyse any problems with an engine in an instant. The screens automatically dim themselves when it gets darker and can be dimmed manually as well, which is ideal for night flights.”, says Mark, beaming with enthusiasm.

The ATR 72-500, features an Electronic Flight Instrumentation (EFIS), with two small CRT

screens per pilot. The remaining gauges are analogue. The ATR 72-600, which was certified by EASA only in the July of 2011, is late to catch up with a full glass cockpit, while the Q400 has sported this in every model delivered since 1998. A glass cockpit allows for a clean, uncluttered, organised and prioritized display of colour coded information.

The aircraft comes with a Flight Management System, and for Siddharth Srinivasan, who is a Type Rating Instructor on the Q400, as well as a line Captain at Colgan (serving Continental Connection’s routes), “The glass cockpit is good. Having flown both glass and steam gauges I definitely give glass the thumbs up. The FMS is a good step and very important to ensure full use of the capabilities of the glass cockpit.”

The PW150A engines on the Q400 are controlled by FADEC (Full Authority Digital Engine Control), unlike the PW127s in the ATR which are controlled by an EEC (Engine Electronic Control). The FADEC provides automatic engine protection against out-of-tolerance operations, while reducing the number of parameters to be monitored by flight crew. The FADEC also provides semi-automatic engine starting, while also providing engine long-term health monitoring and diagnostics. With the number of external and internal parameters used in the control processes increasing by one order of magnitude, a FADEC engine can deliver better fuel efficiency (relative to identical non-FADEC controlled engine).

Aircraft Sales and Production

The ATR 72 was introduced in the October of 1989, with Finnair as the first customer. Born out of an ATR42, in response to the need for a 70-odd seat plane, the ATR 72 has in total delivered close to 410 aircraft over 22 years. The most popular has been the -500 variant, selling about 290 airplanes since its introduction to service in 1997.

The Q400, although conceived much later, was born out of a similar requirement. With deliveries starting in 2000, 357 Q400s (including Q400 NextGen) have been delivered over the 11 year period. This on average translates to 32 Q400 deliveries per year, as against 21 ATR 72-500s per year.

If these numbers are anything to go by, the Q400 has proved its popularity, though the geographical markets of the Q400 and the ATR72 are almost complimentary to each other. The ATR 72’s presence is poor in USA and nonexistent in Australia, while the Q400 enjoys a good representation all over except in Asia with only 3 independent operators cumulatively flying 32 aircraft: ANA, JAC, and PAL Express.

While ATR builds planes in Toulouse, sharing resources and technology with Airbus, and is part of a European Consortium, Bombardier Aerospace is smaller, though only the third largest commercial aircraft manufacturer in the world. This is enough to make the Canadian manufacturer significantly sensitive to world economy and the health of the global airline business. In the April of 2008, With demand for turboprops shifting toward the larger models, Bombardier Aerospace had decided to focus on the Q400 by ceasing production of all other Dash 8 variants, leaving ATR as the only western producer of a 50-seat turboprop. In the Jan of 2009, Bombardier was mulling a boost in Q400 production rates following a delivery backlog of 113 aircraft. Eventually, this did happen. In the September of 2010, Bombardier Aerospace Chief Operating Officer Guy Hachey said that a regular stream of new, albeit small, orders for Q400s meant that production rates could be sustained. But in the June of 2011, Bombardier opted to reduce Q400 production rates while awaiting sales campaigns to materialise, after few prospective customers put their orders on hold.

For ATR, things are moving the other way with their next generation ATR 72-600. Since launching the -600 series programme in October 2007, ATR has received orders for a total of 165 ATR 72-600 aircraft. Demand for the ATR 72-600 has been very strong over the last 12 months due to its apparent attractive operating economics, proven reliability of the family of products, and latest avionics suite upgrade over the ATR 72-500. ATR delivered 51 aircraft in 2010 and is keeping production in 2011 in the region of 50-53 aircraft. ATR still plans to raise production next year to 70 aircraft, and possibly further in 2013-14 if the airframer is confident that the supply chain can cope.

While the sales figures are vastly different for the Q400 NextGens and the ATR 72-600, Bombardier and ATR seem to share the same view on the future of the airline industry. In its 20-year forecast, ATR anticipates a demand for 3,000 turboprops with a sale volume in excess of $20 billion, and is convinced that 30% of the demand for 3,000 turboprops over the next 20 years would be met by a larger aircraft. Bombardier, in its 20 year forecast, anticipates a total demand for 6,100 aircraft in 20-99 seat segment. Of the 6,100 aircraft deliveries predicted from 2011-2030, 2,500 aircraft will be turboprops. Bombardier is quick to work on a bright future; a 90-seat stretched Q400 is on the cards.

Conclusion

The number of Q400 aircraft flying today is indicative of the aircraft’s immense potential and proven economics. No further orders are being taken for the popular ATR 72-500; the well selling -600 will replace the -500 on the production line. With the ATR 72-600 imbibing some good features of the Q400NextGen, such as LED lit cabin and a full glass cockpit, differences between the aircraft are reducing, though only cosmetic.

The Q400 and the ATR72 are two aircraft in their own leagues, beyond a true comparison. The Q400 offers immense operational flexibility and unparalleled performance, while requiring only one aircraft type for most missions. The ATR 72 wins over the Q400 in the operating economics, from the start to the finish. The ATR 72 is less expensive to purchase, to operate, and goes out with a good resale value to cost sensitive operators due to a high demand for the type.

Spicejet has based the Q400s at Hyderabad, serving 11 destinations. While the airline will start reaping the benefits of a turboprop in its fleet from the 21st of August 2011, how the airline uses the Q400 to its fullest, and the manner in which it complements its 737 fleet is to be seen.

It must be remembered, the Q400 was designed as a jet aircraft replacement; not as a mere turboprop.

Credits

Primary contributors who fly the Q400

Mark Brouwer

Mark Brouwer is a First Officer for Augsburg Airways, which is a Lufthansa Regional partner airline based in Munich, Germany. With a total of just over 1500hrs, around 1200 of which are on the Dash 8 Q400, he just had his Airline Transport Pilot License “unfrozen”.

Siddharth Srinivasan

Siddharth Srinivasan is a Captain and Type Rating Instructor (TRI) at Pinnacle, which is headquartered at Memphis, USA. His 5000+hrs of experience includes time on the Q400, and the Saab 340. Pinnacle flies routes for Continental Connection.

Primary contributors who fly the ATR72-500

A K

A K is a senior first officer with Kingfisher airlines, flying the ATR72-500 aircraft. With more than 2200hrs of experience and an ATPL, she is set to move onto the Airbus A320 with a private low cost airline in India.

A T

A first officer with a private airline in India, rated on the ATR72-500. Despite being newly released, he has an eye for detail and thirst for knowledge which makes him an valuable contributor. Yet, he humbly adds, “I am an FO and have a long way to go”. [Photo removed on request]

Contributors who fly the ATR72-500

B B

A commander with Kingfisher Airlines. She has a total of 3000hrs, of which 600hrs are in command of the ATR72-500. She is the youngest captain in the country, having got her command at the age of 21.

C J

A senior first officer based out of Delhi, flies both the ATR72 and the ATR42 aircraft for a private airline in India. He has 2500hrs of flying experience, and holds an Airline Transport Pilot License.

Note: All Indian Contributors’ names have been removed to protect their identity.