SAE Pub Paves the Way for Fuel Savings and Sustainability

The global aviation industry continues to place a high priority on sustainability—balancing economic, social, and environmental factors to ensure long-term health for both the planet and the industry. Significant strides have been made through technological advancements and behavioral shifts. Among the most impactful strategies are aircraft weight reduction and optimized flight altitudes, both of which directly reduce fuel consumption.

The interplay between fuel and oxygen systems is receiving significant attention, particularly in Extended Operations (ETOPS) and overwater flight planning. This is sparked by the imminent release of SAE document AIR5648B, which, for the first time, thoroughly explains the relationship between fuel systems and oxygen systems. (https://www.sae.org/standards/content/air5648b/)

From PSI to Practical Metrics: Time and Distance

Traditionally, aircraft oxygen systems were managed using pounds per square inch (PSI)—a measurement that offers little intuitive value to pilots.

AIR5648B moves the industry forward by introducing time- and distance-based metrics for oxygen management, aligning with the way pilots already manage fuel. Time and distance are the currency of flight planning, and applying these to fuel and oxygen resources facilitates a more integrated and effective approach to emergency and contingency planning.

Flight Plan to a Higher ETP Diversion Altitude

Under current rules, scenarios such as an engine failure followed by a cabin decompression require flight planning at 10,000 feet, where oxygen planning is not mandated. However, regulations do permit higher diversion altitudes, provided adequate oxygen planning is in place. While these requirements are for flight planning purposes only, pilots retain emergency authority to deviate as necessary in real-time operations.

Flight planning to a higher ETP diversion altitude—for instance, 20,000 or 25,000 feet rather than the standard 10,000—can produce substantial fuel savings (“ETOPS ADD” or “ADD ETOPS fuel”). This is the additional fuel needed to fly less efficiently to a lower-altitude diversion airport.

By planning to fly higher in an emergency diversion scenario, aircraft can reduce both the amount of contingency fuel required and the overall aircraft weight at takeoff, thereby increasing efficiency and sustainability.

How Much Can You Save?

Fuel savings for ETP diversions can be significant:

• Corporate aircraft with 3-hour ETP times can typically save 1,200–3,000 lbs. of fuel.

• Commercial wide-body aircraft have reported ADD ETOPS fuel values of 9–10 tons—fuel that need not be carried with higher-altitude planning, yielding both cost and emissions reductions.

Gaseous Oxygen Systems vs COGs

The extent of these savings depends on the type of oxygen system installed:

• Gaseous Oxygen Systems (typically found on corporate and some commercial  aircraft): Allow for extended high-altitude flight (up to 25,000 feet), making them well-suited for higher-altitude ETP diversion planning and resulting in greater fuel savings.

• Chemical Oxygen Generators (COGs): Limited to 12–22 minutes of supply, these are designed for emergency descent only and do not support prolonged high-altitude diversion. This limits the ability to plan for larger fuel-saving altitudes, but any increase above 10,000 feet will yield a savings.

In corporate aviation, where gaseous oxygen systems are common, operators can request a second ETP at a higher altitude using the same diversion airports. Planning services like World Fuel can generate these comparisons upon request and the pilot/operator can easily see the reduction in fuel required.

A Strategic, Sustainable Shift

Oxygen is rarely used—only during decompression events—yet must always be carried. By leveraging technology while still complying with existing regulations, pilots can now intelligently substitute oxygen capacity for excess fuel, significantly improving efficiency.

In essence, fuel and oxygen are tradeable commodities in flight planning. With proper systems and tools in place, the aviation industry can unlock long-standing efficiency potential—one that aligns perfectly with its sustainability goals.