KLM Cityhopper flew a single Embraer 195-E2 round trip between Amsterdam and Dublin on 30 September to trial SITA's OptiDescent fuel-saving technology, becoming the first airline to test the descent-optimisation tool. The carrier estimates an optimised top of descent could save roughly 15-30kg of fuel per descent — a figure that scales quickly against a schedule of more than 10,000 flights a month.

The trial ran under SkyTeam's Aviation Challenge initiative and covered one outbound and one return sector on the Dublin-Amsterdam route. SITA is still analysing the flight data. KLM stresses the exercise was deliberately narrow in scope.

"The purpose was not yet to conduct a large-scale fleet trial, but rather to gain an initial understanding of how OptiDescent could work in a real operational environment and what benefits it could potentially provide," the airline says.

What does OptiDescent actually do?

OptiDescent sits within SITA's OptiFlight suite, alongside OptiClimb, OptiDirect and OptiLevel. The tools use predictive modelling to generate the most fuel-efficient trajectories for each phase of flight.

In the descent phase, OptiDescent keeps the engines "at or close to idle for as much of the descent as operationally possible", according to KLM. That translates into lower fuel burn, reduced carbon-dioxide emissions and less noise around airports.

KLM Cityhopper already has operational experience with one module of the suite: it has deployed OptiClimb since 2024. The regional arm says that technology has delivered measurable results on two fronts:

• reductions in fuel consumption and associated emissions;
• steeper climb profiles that cut noise impact around the airports served by its Embraer fleet.

"There is the potential to further reduce noise impact by avoiding unnecessary flight at lower altitudes," KLM says of the descent tool. Given that Cityhopper operates more than 10,000 flights a month, the carrier believes "the cumulative fuel and emissions savings could become substantial".

Is a fleet-wide rollout coming?

Not yet. KLM characterises the 30 September activity as "a single flight, rather than the start of a defined trial period". The tool itself, the airline notes, is still at an early stage of development.

Still, the two companies are continuing to work together. "We are working closely with SITA to further develop and assess the concept," KLM says. "If the further trials and evaluation deliver positive results, we will explore how OptiDescent can be implemented more widely."

Any wider implementation carries a structural condition: it can only be achieved, KLM stresses, "in close co-operation" with both SITA and air traffic control. Descent optimisation depends on ATC approval of trajectory changes, which makes the regulator-to-provider relationship as decisive as the software itself.

What else was on the Dublin flight?

The Aviation Challenge trial bundled two additional operational measures alongside the OptiDescent test:

• KLM's ground handler, Swissport, used "as much electric equipment as possible" in ground operations at Dublin airport;
• the airline tested a redesigned in-flight service trolley with added compartments for recyclable materials, aimed at cutting onboard waste.

For now, OptiDescent remains a proof of concept rather than a certified operational tool at KLM. The 15-30kg per-descent saving is an estimate, not a verified fleet-wide figure, and SITA's analysis of the 30 September flights is still under way. If the numbers hold up in subsequent evaluation, a carrier flying more than 120,000 sectors a year has a clear incentive to move from single-flight trial to defined test programme.