Aviation & Transport

Aviation and transport facilities share a problem that makes detection harder than the gas itself suggests. The same building contains large volumes of fuel and running engines, so the thing you need to detect and the thing most likely to cause a false alarm are chemically similar.

Most of what follows comes from work our Technical Consultants have done on Australian hangars, helipads and loading facilities.

Aircraft Hangars: Where To Put The Gas Detectors

Inside a hangar, aircraft fuel is the major risk, and early detection of a spill through fuel vapour detection is the first tier of an effective fire and gas system rather than a supplement to it.

AVGAS and Jet A-1 vapour is kerosene based, which means it is heavier than air and it collects low. Hangars are designed for that, with drainage channels under floor grills and covered sump pits to collect liquid releases.

Which is where the detectors belong. Mounting sensors inside the covered drainage channels and sump pits gives the fastest possible response to fuel run-off, because that is where a spill actually goes. It also puts the sensors in protected positions, out of the way of aircraft and vehicle movements, which on a hangar floor matters.

Two calibration points follow from the fuel type. Catalytic flammable sensors on a 0 to 100 percent LEL range are the usual choice, but for best response to aircraft fuel vapour they should be calibrated on pentane or hexane rather than methane. Calibrating on methane and expecting an accurate reading on kerosene vapour is a common error.

Where large quantities of water run-off cause fuel and water to mix, a photoionisation sensor is worth considering instead. Fuel mixed with water has a lower vaporisation rate, so the LEL reading understates what is present, while a PID measuring in parts per million responds far more sensitively to the aromatic hydrocarbons. The Falco 2 provides that as a fixed installation.

There is one practical problem with putting sensors in sump pits, and a good answer to it. Servicing and calibration access is difficult under a drain grill. Where possible, install with extra cable length coiled at the sensor, so the detector can be lifted to the surface and calibrated while still powered and connected to the system. That single detail saves a great deal of time over the life of an installation.

AS 60079.29.2 covers the selection, installation, use and maintenance of flammable gas detectors, and the Australian Department of Defence Manual of Fire Protection Engineering addresses aircraft hangars specifically in its Chapter 13.

Aircraft Hangars: The Underwing Problem

An undetected fuel spill that ignites can engulf an aircraft and the surrounding area very quickly, and the place a spill is most likely to occur is the hardest place to watch.

The greatest risk of accidental leakage or spillage is the underwing area, meaning the shadowed space beneath the wings and fuselage. Ignition sources there include static discharge, electrical system malfunction and maintenance activity itself. Some aircraft carry fuel tank heaters, which raises the likelihood of flammable vapour being present. Plastics, electrical insulation and cleaning materials add to fire propagation once something starts.

IR3 optical flame detectors give the fastest detection of an underwing fuel fire at the early ignition stage. Fast response, adjustable field of view and programmability all matter where aircraft wings obscure the high risk area.

The capability worth understanding is that IR3 detects the heated carbon monoxide and carbon dioxide products of a fire rising through the infrared spectrum. It is not solely dependent on direct line of sight to the flame, which means it can detect hidden fires in most applications. For very large aircraft it is still often necessary to site at least one detector for each large underwing area.

Two mounting constraints. Detectors work best high mounted with a 45 degree downward angle. And they must not be mounted above overhead crane rails, because the rails obstruct the field of view.

Certification for this application involves the CSIRO ActivFire scheme, which certifies and lists active fire protection products in Australia including fire detection equipment, alongside EN 54-10. AS 1670.1 Section 7 covers flame detection, and NFPA 409 is the international standard for aircraft hangars.

The Exhaust Problem, And Why It Costs Money

This applies across aviation and transport, and it is the single most expensive failure mode in the sector.

Where exhaust gas is frequent, the heated carbon dioxide and carbon monoxide in it can trigger a flame detector, because those are exactly the combustion products a detector is tuned to find. Where the fire detection system is linked to automatic deluge or foam suppression, a false alarm is very costly in both equipment damage and operational downtime. A hangar full of foam is an expensive afternoon.

The areas where this happens are worth listing, because most of them are in this sector: aircraft hangars, hardened aircraft shelters, helipads whether onshore, offshore or at hospitals, areas of high vehicle activity, waste and recycling facilities, road and rail freight and tanker loading facilities, gas turbine enclosures, and power station engine halls.

The CO2L variant of the IR3 detector exists specifically to solve it. Additional sensor filters across the infrared spectrum, combined with fire frequency pattern analysis in the detector software, allow it to distinguish a genuine heavy hydrocarbon fire from the exhaust around it.

If your protected area contains running engines, specify CO2L. If it does not, the standard variant gives you the performance without paying for optimisation you will not use.

Helipads

Helipads have their own requirement, and it is a hard one rather than a preference.

Civil Aviation Authority publication CAP 437 requires automatic fire suppression covering the landing area, generally triggered by flame detectors around the perimeter aimed toward the centre, with three detectors at 120 degree spacing usually considered sufficient. Mounting is constrained from both directions: as low as possible so as not to interfere with landings, and still inclined downward toward the pad centre.

The problem is rotor downwash driving hot exhaust across the detectors. False activation of a deluge system during a landing would be catastrophic, so hot exhaust immunity is a requirement rather than a refinement. This is covered in more detail alongside offshore helidecks on our marine and maritime page.

Fuel Terminals, Loading Racks And Depots

Road and rail tanker loading is where the exhaust problem and the fuel problem occur together, with vehicles idling in the same space as the product being transferred.

Detection typically combines fixed gas detection at the loading position and in bunded areas, flame detection with exhaust immunity across the rack, and portable instruments for operators working around the transfer. Where the product carries a health exposure risk as well as a flammability one, particularly petrol containing benzene, PID instruments measure at the parts per million level that health exposure actually requires.

Electric Vehicle Fleets And Depots

As transport fleets electrify, depots and charging facilities bring a hazard most maintenance teams have not dealt with before.

Under thermal runaway, fire or physical damage, a lithium battery can release carbon dioxide, methane, ethylene, ethane, fluoroethane, hydrogen and hydrogen fluoride. Where fire is involved, hydrogen cyanide, carbon monoxide and oxygen deficiency are added to that.

The detail that matters for anyone responding is this. In thermal runaway, the vehicle and battery may visually appear to be safe while actively exhausting gas. There is no reliable visual indication, which means a responder standing next to an apparently undamaged vehicle can be in a hazardous atmosphere.

That calls for a wider gas set than a standard four gas instrument covers. Practical ranges are hydrogen fluoride to 10 ppm, carbon dioxide to 5 percent by volume, volatile organics to 2,000 ppm, methane to 100 percent LEL, hydrogen to 2,000 ppm and oxygen to 25 percent, which points at five plus gas instruments with a photoionisation channel.

The same technology has moved into heavy industry, with large battery electric vehicles now in trial at several Australian mine sites, typically using lithium iron phosphate chemistry at capacities around 350 kilowatt hours.

Confined Spaces

Fuel tanks, aircraft fuel cells, tanker barrels, rail wagons, pits and ducts are confined spaces, and entry brings pre-entry testing and continuous monitoring requirements. There is a specific problem with catalytic bead LEL sensors that anyone doing this work should know about, covered on our confined space page.

Standards And Who Regulates

Aviation and transport gas detection sits across several frameworks rather than one.

Workplace safety in a hangar, terminal or depot is general work health and safety law, so the regulator is WorkSafe WA, SafeWork NSW or Workplace Health and Safety Queensland depending on location.

Aviation safety itself is regulated by the Civil Aviation Safety Authority, though aerodrome fire protection requirements come through separate standards rather than through gas detection rules.

Rail operations sit under the Rail Safety National Law, administered nationally by the Office of the National Rail Safety Regulator across all Australian jurisdictions.

Fire detection and alarm systems follow AS 1670.1, with the 2024 edition referenced by the 2025 National Construction Code. Flame detectors are certified through the CSIRO ActivFire scheme and against EN 54-10. Gas detector selection, installation and maintenance follows AS/NZS 60079.29.2. Confined space entry follows AS 2865:2009. For hangars specifically, NFPA 409 and the Defence Manual of Fire Protection Engineering Chapter 13 are the reference documents.

What Gastech Supplies

Fixed gas detection for hangar drainage channels and sump pits, loading racks, bunded areas and fuel storage, with catalytic, infrared and photoionisation sensing depending on whether flammability or health exposure is the concern.

Flame detection including IR3 for underwing coverage and CO2L variants where engine exhaust would otherwise cause false alarms, with HD video options where responders need to see the area.

Portable multi-gas and PID instruments for maintenance, confined space entry, fuel handling and electric vehicle incident response.

Controllers with the relay capacity to drive suppression, ventilation and alarms rather than only reporting a reading.

Behind them sit project engineering, NATA calibration and service, field service, fleet management and hire, from WA, NSW and QLD.

If you are laying out detection for a hangar, or dealing with false alarms from engine exhaust, talk to our Technical Consultants.