A TWO-PART VOYAGE DESIGNED TO PROVE A 23-HOUR BLOCK TIME

On 23 July the first A350-1000ULR flight test aircraft, MSN707, departed Toulouse on a direct flight to Melbourne. Days later it flew the entire distance back, landing in Toulouse on the morning of 28 July after 24 hours and 24 minutes airborne, covering 12,460 nautical miles — the longest flight the aircraft has yet undertaken. Airbus Test Pilot Xavier Pepin captained the return leg. MSN707, which first flew on 2 June, is equipped with specialised instrumentation, and the two-part voyage is classified technically as a development flight test rather than a certification flight test.

The purpose was specific. Airbus needed to demonstrate that the aircraft, powered by two Rolls-Royce Trent XWB-97 engines, can perform a 23-hour block time flight — the duration from releasing the parking brake at departure to setting it at the arrival stand. That figure provides coverage for the customer’s intended flight time of 21 hours and 40 minutes, plus allowances for holding, diversion and taxi at both ends, on the forthcoming Project Sunrise routes. Establishing block time rather than airborne time is the operationally meaningful test, because it is block time that determines whether a route is flyable under real-world conditions with reserves intact.

WHAT THE FLIGHTS WERE ACTUALLY MEASURING

Two systems were the primary focus. The first was cabin comfort, assessed through air conditioning measurements under ATA Chapter 21. The second was fuel management under ATA Chapter 28, and in particular the additional rear centre tank, which carries 20,900 litres and is the modification enabling ultra-long-range operations covering almost 10,000 nautical miles. Pepin explained that much of the rear centre tank’s functionality had already been demonstrated earlier in the flight test campaign, and that these long-range flights finalised the remaining test points — the tank was filled in order to validate all necessary parameters during the mission, making fuel management and cabin comfort the primary focus of the testing.

He added that during the first leg, which lasted approximately 20 hours, the crew also used the time to stabilise various air temperature settings to ensure accurate measurement. Because much of the testing was completed outbound, the return leg was available to address backup test points not covered on the way out. The crew additionally evaluated the ULR’s new twin Flight Crew Rest Compartment, which was extensively instrumented to measure air conditioning performance. The module is designed specifically for the -1000ULR’s ultra-long missions and features two separate dedicated sections with individual entrances, ensuring that in airline service pilots can enter or leave their respective rest areas without disturbing one another.

CREW COMPOSITION AND THE QANTAS PARTICIPATION

The outward leg carried four Airbus pilots, with Test Pilot Vincent Sibelle as captain and responsible for overall mission organisation, joined by Xavier Pepin, Josef Bayoud and Chetan Takalkar. Two Test-Flight Engineers, Laurent Rossignol and Nicolas Granier, were seated in the cockpit monitoring aircraft systems, while three Flight-Test Engineers — Tuan Do, Alexia Plumet and Jaime Angoloti — worked at flight test stations in the main cabin coordinating the cabin comfort and fuel monitoring tests.

For the return leg, Pepin took the captaincy and two Qantas pilots, Captain Andrew Coull and Captain David Summergreene, joined the crew as one Airbus pilot disembarked — producing a flight deck complement of five pilots, three from Airbus and two from Qantas. Both Qantas captains are already qualified on the A350 but were new to the ULR variant, and the flight provided their first experience of it. The engineering crew was unchanged from the outbound sector.

ROUTING AND FATIGUE MANAGEMENT ACROSS 24 HOURS

The return routing took the aircraft out of Melbourne across the Pacific towards Los Angeles, over the United States and Canada, across the Atlantic south of Greenland, over the United Kingdom and into southern France. Pepin explained that a northerly Atlantic path was selected deliberately to avoid the published organised track structure in use by scheduled airlines, which might not have been updated by the time of departure — thereby avoiding potential air traffic control complications such as mismatched flight plans.

Fatigue management across flights of 20 to 23 hours was handled through a structured rotation. Pepin described four-hour shifts for each pilot with the crew rotated every two hours, a staggered approach ensuring that an incoming pilot overlaps for two hours with the outgoing one, facilitating a thorough handover and maintaining full situational awareness throughout. For the second leg, at least one Airbus test pilot was always occupying a pilot seat whenever a Qantas pilot was in the other, since Airbus retained responsibility for the operation. A particular irony of the mission was that the crew could not use the new twin flight crew rest compartments they were there to test — those were occupied by ventilation measurement equipment — so the pilots instead slept in the eight-berth cabin crew rest compartment at the rear of the aircraft. As Pepin noted, with no passengers or cabin crew aboard, the location allowed a rapid return to the cockpit or flight test station at any time. He said the crew had enjoyed exchanging knowledge and addressing the Qantas pilots’ questions during the ultra-long-range voyage.