Chandigarh: The grounding of two RAF F-35B “Lightning II” naval variant fighters for over two months at Lajes Airport in the Azores – a Portuguese archipelago in the North Atlantic about 1,500 kilometres west of mainland Portugal – awaiting technical support, has highlighted growing reliability and sustainment concerns around the US-origin platform, billed as the world’s most advanced stealth combat aircraft.The two Lockheed Martin-designed and series-built 5th generation short take-off and vertical landing (STOVL) F-35B fighters were stranded at Lajes on March 9 after developing technical faults during their delivery flight from Fort Worth, Texas, to Britain, and have remained there since, awaiting repair and re-certification.Reports regarding these disabled F-35Bs suggested possible issues involving their refuelling probes and their inability to successfully connect with the RAF’s Airbus A300 ‘Voyager’ multi-role tanker transport (MRTT), during mid-air refuelling.In operational terms, this refers to difficulties in the fighter establishing or maintaining a stable probe-and-drogue (mid-air refuelling) connection with the tanker – a critical requirement for extending range on long ferry flights. Such issues can arise from probe deployment or locking malfunctions, alignment problems in turbulent conditions or sensor and flight-control integration constraints, which can complicate highly precise aerial refuelling operations.As delivery of the two fighters had not yet been formally completed, the platforms technically remain the property of Lockheed Martin, pending acceptance by the UK. This also means that responsibility for their repair and re-certification was with the manufacturer, rather than the RAF, as aircraft delivery to it had not yet been completed.The Lajes incident follows an earlier episode in mid-2025, involving a similar RAF F-35B that was stranded at Thiruvananthapuram Airport for nearly six weeks during carrier operations, before returning to service. It had been grounded due to a combination of technical and maintenance-related issues, reportedly linked to key onboard systems.Industry sources at the time indicated that the fault required specialist diagnostics and external engineering support, highlighting the challenges of sustaining 5th-generation aircraft outside their primary logistics environment. These had reportedly included malfunctions in the fighters’ hydraulics and auxiliary power unit, which required dedicated support beyond what was immediately available on HMS Prince of Wales, the UK’s 65,000-tonne carrier that supported the F-35Bs as its embarked air wing. Initial fighter repairs by onboard carrier engineers had failed, forcing the RAF to fly in a specialist 14-member engineering team to fix the malfunction in early July 2025.The repaired F-35B finally departed India on July 22, 2025, but not without raising concerns in the US and other Western defence circles over the prolonged exposure of sensitive stealth technology outside tightly controlled North Atlantic Treaty Organisation (NATO) environments, especially as India was not an F-35 programme member.Launched around 1993-94, the F-35 programme is a multinational effort involving 19 countries, either as operators or industrial partners, reflecting its role as a core platform within NATO and allied air power structures. It is also widely regarded as the most expensive military programme in history, with an estimated total lifetime cost of around $1.5 trillion over its full-service life, covering development, procurement and long-term sustainment over 50-60 years.Initial development costs alone are estimated at over $200 billion, while fighter unit prices vary by variant: the F-35A, used primarily by air forces, is $80-100 million per aircraft, with the F-35B significantly more expensive due to its STOVL capability, and the advanced carrier-based F-35C also carries a higher cost because of its naval design requirements. However, operational use of the F-35B STOVL model is limited to only four countries – the US, UK, Italy and Japan – all of whom have incorporated the platform into carrier or expeditionary air operations.Meanwhile, at the time it was grounded in Kerala, images of the disabled fighter circulated widely on social media, where local commentators joked that one of the world’s most expensive stealth aircraft appeared less like a cutting-edge combat system and more like a luxury car awaiting imported spare parts. Beneath the wry humour, however, lay a serious strategic point: modern fifth-generation fighters have become so technologically complex and maintenance-intensive that even relatively minor technical faults can immobilise them for extended periods.But taken together, the two instances in India and the Azores have triggered attention to the F-35B’s persistent reliability concerns, increasingly being viewed not as isolated technical anomalies, but as part of a broader pattern of operational fragility associated with a highly complex, software-intensive combat system.Online research has revealed that F-35Bs, while offering advanced stealth, sensor fusion and networked combat capability, depend heavily on a tightly integrated global maintenance and logistics ecosystem that needs to function seamlessly for sustained operations. Any disruption in this chain – whether in diagnostics, spare parts availability, or specialist technical support – can rapidly translate into prolonged aircraft downtime.This, in turn, has raised questions over the practical resilience of the platform in dispersed or austere environments, where immediate access to manufacturer-level support may not always be available. The operational optics surrounding the F-35 are also difficult to ignore: aircraft designed to represent the cutting edge of NATO air power are instead seen immobilised at remote civilian airfields, awaiting specialist intervention and diagnostic support from manufacturer Lockheed Martin.Analysts note that at the heart of the issue lies the design philosophy of the F-35 itself. Unlike earlier generations of combat aircraft, which prioritised mechanical accessibility and field repairability, the F-35 is a deeply integrated digital weapons system, hopelessly dependent on highly specialised and advanced maintenance environments and tightly controlled global supply chains. Hence, even relatively minor faults can escalate into prolonged grounding if the required diagnostics, software updates or replacement components are not immediately available.This, in turn, creates a fundamental paradox.The F-35 is designed to operate in heavily contested airspace, where its stealth, sensors and networked systems provide a decisive combat advantage. Yet its ability to remain operational depends equally on a stable and secure support infrastructure on the ground. In routine peacetime deployments and ferry flights, this dependence is manageable, as maintenance networks, spare parts and specialist teams are readily accessible. In a crisis or wartime scenario, however, the same reliance becomes far more consequential: if logistics chains are disrupted or support infrastructure is degraded, the issue is no longer simply about survivability in combat, but about whether the aircraft can be sustained or more vitally fielded in service at all.These concerns were further reinforced by a 2025 assessment by the UK’s National Audit Office, supported by subsequent scrutiny from the Public Accounts Committee, which indicated that during 2024 the F-35 fleet achieved only around one-third of the Ministry of Defence’s (MOD’s) target for “fully mission-capable” availability.The report highlighted that the UK’s Lightning Force – a joint Royal Air Force and Royal Navy formation responsible for operating the F-35B Lightning II fleet – faced an engineering and ground crew deficit of roughly 170 personnel, a gap the MoD expects to take several years to close due to the specialised and highly technical nature of the role. In parallel, delays in spare parts delivery and broader logistical bottlenecks have resulted in extended maintenance cycles, with aircraft frequently grounded beyond planned targets.Operational F-35B deployment from UK carriers had also introduced additional strain, with prolonged exposure to maritime environments contributing to higher-than-expected corrosion and structural wear of platforms requiring lengthy repair periods. At the same time, limited aircrew depth – reflected in a near 1:1 pilot-to-aircraft ratio – had further constrained operational flexibility, particularly in scaling up training and sortie generation rates.Yet, despite such enduring reliability concerns, the UK and the rest of NATO remain committed to the F-35 because it delivers capabilities few platforms can match – rendering it less a traditional fighter and more a highly integrated information-processing platform central to modern air warfare.But this deep integration is also its weakness, as it depends on complex global supply chains and specialist support, raising doubts about how well it can be sustained in prolonged conflict if logistics are disrupted or maintenance access is limited. There is little doubt that the F-35 represents technological dominance, but in modern air power, the decisive factor is no longer just performance in flight – it is sustained operational availability under pressure that ultimately counts.