12 I AIRLINE & AIRCRAFT OPERATIONS Sander de Moor, director airline operational efficiency at Aircraft Commerce Consulting examines the fuel burn & operating performance of the A350-900 & -1000. They are compared with the 787 and older generation 777 & A330 families; and the 747-400. A350-900/-1000 fuel burn & operating performance he 787 and A350 families both them being the cabin layout and seat would be the addition of the cost of promised significant fuel burn numbers. There is a large discrepancy overflying countries (‘airspace access reductions over similar-sized, between the Airbus standard cabin costs’). These may be referred to as air Tolder generation aircraft, as well layout, and airline cabin layouts. The traffic control (ATC) user fees. as more range with the same payload. difference is large enough to warrant The number of available-seat miles Examples of the realised efficiency gains inclusion of the two versions. (ASMs) generated by each aircraft on over older aircraft types are analysed here The three 787 variants and the two each route are calculated by multiplying across five long-range and ultra-long- A350 variants were compared with the number of available seats in the range transatlantic sectors between several main types. The first is the 777- aircraft (see tables, pages 18 & 19) by the London and points in North and South 200ER and 777-300ER, which are actual flown distance, the equivalent still- America. These have tracked route included as examples of previous- air distance (ESAD). ESAD is the distance lengths ranging from 4,330nm to generation efficiency in this market. The travelled by an aircraft through the air, 6,450nm on flight times of nine hours 777-200ER competes most closely with rather than the tracked distance, and is and 40 minutes to about 14 hours. the A350-900 and the 787-10 in terms of affected by wind and altitude. A relative In this article we will run our seat capacity, while the 777-300ER wind vector will make the aircraft cover comparative fuel burn and operating compares closely with the A350-1000 on more or less ground distance per time performance analysis on a suite of latest- the same basis. unit, while altitude influences the number generation comparable aircraft in various The A330-200 was also included as a of tracked miles to be covered due to the airframe-engine combinations. We will similar-sized and previous generation earth’s curvature, and whether an aircraft also compare these modern types with aircraft to compare with the 787-8, and travels a longer distance to cover the some of their previous-generation the A330-300 was included on the same same arc along the flight path between competition. Fuel burn will be compared basis to compare with the 787-9. two points on the ground. The ESAD of on an absolute and per available seat-mile Last, the 747-400 was included, each route used in the analysis is given (ASM) basis. As always, aircraft because it has been replaced by the 777- (see table, page 15) . These vary slightly performance and fuel burn analysis is 300ER and more recently by the A350- by aircraft type because of flight profiles, provided by Lufthansa Systems, and our 1000. The relative efficiency will be but range from 4,705nm to 6,941nm (see conclusions are our own. shown of fuel burn per ASM of the twin- tables, page 18 & 19) . engined configuration of these two It is important that ASMs are younger generation types against the calculated using the number of available Aircraft types & variants 747’s four engines and configuration with seats. If some aircraft seats are All production versions of the two more seat numbers. unavailable for sale due to regulatory, main types in our evaluation were In total, 14 different aircraft variants performance or technical reasons (such as included, meaning Boeing’s 787-8, 787-9 are included in this analysis, and their unserviceable seats, seats dedicated for and 787-10; and Airbus’s A350-900, and weights, fuel capacities, engine types and crew rest) then such seats cannot be A350-1000. The Airbus A350-900ULR is seat numbers are detailed (see table, page included in the ASM metrics of affected not included, because this aircraft type 14) . flights. If the aircraft has a payload falls outside our scope of a general restriction on a longer route, then only comparative evaluation. the number of seats that can be used are As there are two engine manufacturer Comparison basis the same in the ASM calculation. This is options for the 787 family, both aircraft- This group of 14 aircraft was the case for a few aircraft types on the engine variants for each of the -8, -9 and - compared at three levels. As described, longest route in this comparison, and 10 series were included. the first two were relative fuel burns on resulted in a high fuel burn per ASM. Last, two variants of the A350-1000 an absolute basis, and then on a fuel burn On the London Heathrow (LHR) - are evaluated, the difference between per ASM basis. The third comparison Rio de Janeiro (GRU) route, the A330- AIRCRAFT COMMERCE ISSUE NO. 121 • DECEMBER 2018 / J ANUARY 2019 13 I AIRLINE & AIRCRAFT OPERATIONS The A350-900 and -1000 series demonstrate significant fuel burn reductions over previous generation aircraft. The A350-900 has a 17.5% lower burn per ASM compared to the 777- 200ER, while the A350-1000 has a 11% lower burn per ASM than the 777-300ER. Flight Rules (IFR) with alternate, 5% contingency fuel; fixed-Mach cruise (LRC), fixed routes, 0% aircraft performance degradation, 85% average winds for June, all-engine taxi operations, normal standard operating procedures. Lufthansa Systems’ Lido/Flight 4D optimises climb, cruise and descent segments of a flight based on performance specifications (data files) of the particular airframe-engine combinations, as received from the aircraft original equipment manufacturers (OEMs), as well as specific operating 300 had to surrender 27 seats; while on ranging from -31 to -37 knots, these philosophies (flight level caps, the LHR- Buenos Aires (EZE) route routes have ESADs of 5,479 nm to 6,924 performance degradation factors, available seat count was lowered by 49 nm (see table, page 15) . amended performance buffers in seats on the A330-200, 128 seats on the planning, padding) as requested by its A330-300 and 68 seats on the two-class customers. If not creating an optimised 747-400. On the longest route, LHR- Operating parameters route itself, once a route has been Santiago de Chile (SCL), even the A350- Aircraft performance was examined decided, Lido/Flight will plan an 900 had to leave three seats unoccupied. using operating empty weights (OEW) optimum vertical profile based on The chosen five routes include three and zero fuel weights (ZFW) on the basis parameters applicable to the aircraft and ultra-long-range sectors. All five routes of operating a typical two-class, full- its operator, achieving an overall lowest originate from LHR. Two are to points in service operation. Aircraft configurations total cost solution for the planned flight the US, and have tracked distances of vary from airline to airline, both in terms by balancing cost of fuel burn, time- 4,330-4,811 nm. The three longest routes of installed equipment and cabin related costs and airspace access costs. are from LHR to cities in South America, configurations, starting with the specified Climb and descent profiles differed and have tracked distances of 5,155- manufacturer empty weight (MEW). It is per aircraft type of course. Cruise mode 6,450nm. These three longer routes were therefore difficult to select an OEW that for all aircraft types and variants on all included so that the relative performance will fit all operators of each type for this routes was at fixed-Mach LRC. More of each aircraft could be examined when comparison. MEWs alone differ operators are moving away from fixed- departing from an airport where there are significantly from operator to operator, so Mach cruise modes, such as a specific no take-off weight or performance the chosen weights may vary significantly Mach number or long-range cruise (LRC) restrictions. This will illustrate the from what is found in a specific airline’s in favour of Cost Index (CI) flying, which relative economic feasibility of the 14 configuration. As such, the chosen weight is a more cost-conscious and economic aircraft types on long-range and ultra- may have an effect on the resulting fuel way of managing operating costs. long-range routes. burn computations or payload-range However, since CI flying relies heavily on Aircraft performance and fuel burn capacity. Furthermore, the aircraft were operator internal cost structures and fuel were not analysed in the opposite planned to operate with a full payload of prices, no two operators plan and operate direction, since SCL’s elevation could passengers, and an allowance of 231lbs flights using the same CI. This in turn cause performance restrictions or per passenger and associated baggage. would mean that a flight-for-flight limitations for some aircraft types, and so This resulted in relatively high passenger- comparison would not be possible. For influence the comparison. related payloads for each type. It is also this reason, fixed-Mach LRC speed was The two destinations in the US are higher than most scheduled airline selected. Austin (AUS), Texas; and San Diego operations are likely to experience in this Last, to create the same atmosphere (SAN), California. These two routes have fashion. Lower deck cargo was excluded, for all aircraft types to operate in, tracked distances of 4,330nm and however, but the cargo payload that statistical average winds and 4,811nm (see table, page 15) .