Landing on empty: estimating the benefits from reducing fuel uplift in US Civil Aviation

Abstract

Airlines and Air Navigation Service Providers are united in their goal to reduce fuel consumption. While changes to flight operations and technology investments are the focus of a number of studies, our study is among the first to investigate an untapped source of aviation fuel consumption: excess contingency fuel loading. Given the downside risk of fuel exhaustion of diverting to an alternate airport, airline dispatchers may load excess fuel onto an aircraft. Such conservatism comes at a cost of consuming excess fuel, as fuel consumed is a function of, among other factors, aircraft weight. The aim of this paper is to quantify, on a per-flight basis, the fuel burned due to carrying fuel beyond what is needed for foreseeable contingencies, and thereby motivate research, federal guidance, and investments that allow airline dispatchers to reduce fuel uplift while maintaining near zero risks of fuel exhaustion. We merge large publicly available aviation and weather databases with a detailed dataset from a major US airline. Upon estimating factors that capture the quantity fuel consumed due to carrying a pound of weight for a range of aircraft types, we calculate the cost and greenhouse gas emissions from carrying unused fuel on arrival and additional contingency fuel above a conservative buffer for foreseeable contingencies. We establish that the major US carrier does indeed load fuel conservatively. We find that 4.48% of the fuel consumed by an average flight is due to carrying unused fuel and 1.04% of the fuel consumed by an average flight is due to carrying additional contingency fuel above a reasonable buffer. We find that simple changes in flight dispatching that maintain a statistically minimal risk of fuel exhaustion could result in yearly savings of 338 million lbs of CO 2 , the equivalent to the fuel consumed from 4760 flights on midsized commercial aircraft. Moreover, policy changes regarding maximum fuel loads or investments that reduce uncertainty or increase the ability to plan flights under uncertainty could yield far greater benefits.

Benefits of Aviation Weather Services: A Review of International Literature

“…The provision of very accurate information about the weather conditions of the destination airports and aerodromes as contained in the TAFs or TTFs is crucial in the optimal decision to carry discretionary fuel and/or to divert to an alternate airport or aerodrome. The findings of Ryerson et al (2015) have been established in earlier studies by Leigh (1995), Leigh et al (1998) and Anaman et al (2000) for the Australian carrier, Qantas Airways.…”

“…By quantifying the cost of fuel uplift for contingencies and highlighting the existing fuel benefit pool from reducing fuel uplift, Ryerson et al (2015) estimated the benefit of an airline reducing fuel uplift beyond a certain level of uptake. They defined the cost side to include any possible increase in the number of diversions that the airline might experience as an aircraft was not likely to simply run out of fuel mid-air, but instead would more likely divert safely to another airport.…”

“…It is often argued that diversions come with a significant cost as they are disruptive to the focal point of operations involving rescheduling take-offs and landings for various airlines using the airport. Ryerson et al (2015) found that there were large benefits in fuel savings with the most conservative fuel loading practices suggesting that there existed benefits to be exploited with minimal impacts on airline operations by an analysis of various operating scenarios. The provision of very accurate information about the weather conditions of the destination airports and aerodromes as contained in the TAFs or TTFs is crucial in the optimal decision to carry discretionary fuel and/or to divert to an alternate airport or aerodrome.…”

“…By varying the route, altitudes, speeds, and amount of departure fuel, an effective flight plan can reduce fuel costs, time-based costs, over flight costs, and lost revenue from payload that could not be carried (Altus, 2009). Altus (2009) further argues that accurate, optimized flight plans can save airlines millions of gallons of fuel every year without forcing the airlines to compromise their schedules or service; this point is also noted by Ryerson et al (2015). The potential savings of millions of gallons of fuel are due to the recognition that flight planning must include availability of accurate and timely weather information, the performance capability of the aircraft, other operational constraints of the airline company and other factor such as the physical conditions of the aerodrome.…”

“…Therefore the reduction of greenhouse gases by aircraft should be taken from the perspective of a complete managerial analysis of the airline company including the possibility of acquiring newer and fuel-efficient aircraft and also including the role of improved weather forecasts in reducing fuel use. Ryerson et al (2015) provide a more recent study on the possibility to minimise the environmental impacts of the emissions of carbon dioxide by airlines through carrying less discretionary fuel which is possible based on the use of improved weather forecasts. As described in the earlier section of this paper, airlines normally carry excess contingency fuel to reduce the downside risk of diverting to an alternate airport when the weather is bad for landing at the designated aerodrome.…”