The Paris Airshow in 2023 has been dominated by hydrogen talk. From retrofit demonstrations to large OEM concepts, the industry is showing tangible steps toward hydrogen propulsion. That is exciting, but as a line pilot and safety consultant I want to focus on the operational realities that are not solved by concept art alone. Hydrogen changes some of the basic assumptions pilots and ground crews have relied on for decades. If we do not address these now we risk creating new hazards while trying to remove old ones.

What the show made real

Several demonstrators and programs on display are worth noting because they move hydrogen from whiteboard to operational test. Universal Hydrogen and partners flew a Dash 8 configured to run principally on a hydrogen fuel cell powertrain earlier in 2023, proving megawatt-class fuel cells can be integrated into regional types. ZeroAvia was on-site to brief customers about its hydrogen-electric powertrains for 9- to 19-seat aircraft and commercial timelines aimed at regional operations. And major suppliers are working the cryogenic and supply side: MTU Aero Engines and MT Aerospace announced a joint project to develop a liquid hydrogen fuel system for commercial aviation at the show. Finally, the regulatory ecosystem is starting to respond. The Alliance for Zero Emission Aviation and EASA have published mappings of standards and regulatory tasks to prepare the European system for hydrogen and electric entrants. Airbus first unveiled ZEROe concepts back in 2020 and continues to push architectures that will inform certification and operational practices as the technology matures.

Those developments are important because they move hydrogen into the parts of aviation that matter to safety: weight and balance, fuel system architecture, ground handling, emergency response, and human factors. Below I outline the concrete safety challenges operators and pilots need to be planning for now.

Core safety challenges

1) Fuel state and packaging

Hydrogen can be carried as compressed gas or as cryogenic liquid. Liquid hydrogen packs greater energy per volume but requires cryogenic tanks, insulation, management of boil-off and different refuelling interfaces compared with Jet A. Those tanks are large, need special placement to preserve CG limits, and introduce thermal and pressure hazards that crews have not had to treat before. The handling protocols for cryogens are different from hydrocarbon fuels and will require new procedures and training.

2) Leak modes and detectability

Hydrogen is odorless, colorless and has a wide flammability range with a very low ignition energy. It also has a high diffusivity which helps it disperse but also means small leaks can travel into crevices. Unlike Jet A, hydrogen flames are nearly invisible in daylight. That undermines intuitive visual cues for ground crews and flight crews responding to a fuel leak or an overheat. Robust leak detection and gas monitoring at tanks, pumps, vents and inside compartments will be mandatory. Fuel system designers and airports must assume human senses are unreliable and equip facilities and aircraft with automatic detection and isolation.

3) Tank placement and crashworthiness

Airframe integration choices matter. Some early concepts store liquid hydrogen behind the rear pressure bulkhead; others put tanks in the wing area or in blended wing bodies. Each option changes crash and post-crash fire dynamics, evacuation paths, and structural load paths. Certification and operational procedures must address the unique damage and post-impact behaviours of cryogenic tanks and lines. That means new damage-tolerance margins and emergency evacuation guidance for passengers and crew.

4) High voltage and thermal management

Hydrogen fuel cell architectures add high-voltage electrical systems and large battery or buffer systems for transient power. That creates concurrent hazards: electrical shock, thermal runaway of batteries, and interaction between electrical faults and hydrogen leaks. Maintenance practices must treat hydrogen systems and high-voltage systems as an integrated hazard, not isolated disciplines. That has direct consequences for de-icing, towing, refuelling, and rescue operations.

5) Ground operations and airport infrastructure

Bringing hydrogen to airport ramp level is not just a fuel truck change. Airports will need certified storage, vapour management, designated fan and venting zones, trained firefighting teams, and harmonized checklists for ground personnel. Airports and ground handlers must be treated as safety-critical partners in a carrier’s operational approval. Early aircraft demonstrations show the technology can work, but scaling requires airports to be hydrogen-ready or the whole concept fails at the operational level.

6) Regulatory and standards gaps

Industry alliances and EASA mapping work are underway, but the regulatory framework for licensing, maintenance, dangerous goods classification and airport operations will need harmonization across states. The aviation system is global and airline networks will not tolerate fragmented rules. That regulatory lag is one of the biggest operational risks because pilots and operators depend on clear, harmonized requirements to build safe procedures.

Operational mitigations pilots and operators should demand now

  • Treat hydrogen readiness like any other airworthiness modification: rigorous failure mode and effects analysis, clear maintenance manuals, and formal training syllabi for flight crews and maintainers.

  • Require certified hydrogen leak detection and automatic isolation in fuel lines, tanks, and ground couplings. No manual-only mitigations.

  • Develop and drill emergency procedures that account for invisible flames, rapid dispersion, and cryogen Burns. Communicate those procedures to airport rescue and firefighting services and include hydrogen scenarios in full-scale exercises.

  • Integrate hydrogen fuelling into flight dispatch and ground time planning. Refuelling will likely take different timelines and may impose new turnaround constraints that affect fuel planning and dispatch margins.

  • Update maintenance human factors training. Technicians must be qualified to work around cryogenic systems and high-voltage interfaces. Cross-disciplinary training that covers hydrogen, electrical systems and thermal management is essential.

  • Push regulators for harmonized ground handling standards and for clear guidance on tank damage tolerances, safe refuelling envelopes, and refuelling interlocks.

A pilots perspective on timelines and risk

Flight demonstrations in 2023 show feasibility at the regional scale. That is where hydrogen will most likely appear first because aircraft are smaller, flight profiles are more predictable, and airport distances are short. But pilots should not mistake demonstrator success for operational maturity. The safety envelope includes hardware, procedures, airport readiness and emergency services training. Each of those is a potential single point of failure if not addressed with depth.

The industry needs to move beyond PR milestones and into disciplined risk management: get the standards drafted, field the detection equipment, train and certify personnel, then expand operations. If we sequence technical milestones and operational approvals correctly hydrogen offers a way to cut lifecycle CO2 from certain mission profiles. If we rush that sequence we may trade one safety problem for another.

What regulators and operators must do next

Regulators should accelerate harmonized certification criteria and publish interim guidance for hydrogen retrofits and new types. Operators should demand clear compliance roadmaps from OEMs, engine and fuel system suppliers that include human factors, maintenance, and airport-interface requirements. Airports must be part of the operational concept from day one. The work EASA and industry alliances have started is essential. It must lead rapidly to concrete, harmonized standards and practical ground rules so that pilots, maintainers and airport crews can operate hydrogen aircraft without guesswork.

Bottom line

Hydrogen aircraft concepts at Paris will be a thread in the future of aviation, not an immediate replacement for Jet A across the network. That makes the near-term safety work crucial because the first operational hydrogen flights will set the norms. Pilots and operators need to be blunt about the gaps and insist on the detailed, tested procedures that keep our people and passengers safe. We have the technical momentum. The next step is to pair that momentum with rigorous operational discipline.