Exhaust Fumes in Hangar 2
At 07:20, during pre-flight inspection in Hangar 2, you notice a faint exhaust smell. A ground run of a trainer engine finished 10 minutes earlier. The roller doors are open, but the wind is calm. Two cadets report headaches; one is drowsy and nauseated. There is no carbon-monoxide detector in the hangar. A portable gas detector in the next bay reads normal for fuel vapour but has no CO sensor. The squadron duty officer is 400 m away and not answering the radio. A visiting senior officer is due at 08:00. You have 14 cadets in the hangar, one first-aid kit, and a landline in the crew room. A corporal says, 'It is just exhaust; open the back door and carry on.' You must decide.
1. Set out your immediate actions and explain why you reject the corporal's advice.
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Treat it as a carbon-monoxide exposure until proved otherwise. Evacuate all 14 cadets to fresh air, upwind of the hangar, and take a name check. Call medical and the duty officer from the landline. Keep the drowsy cadet lying down, monitor breathing, and send for an ambulance; do not let anyone drive themselves. Ventilate only from outside with fans, and do not re-enter until a CO meter reads safe. Shut down any likely source if it can be done without entering. Reject the corporal's advice. Opening the back door does not clear CO quickly in a large hangar with calm wind, and the drowsy cadet is already a warning sign. The faint smell is not a reliable guide; CO itself is odourless. The immediate priority is people, not the 08:00 visit. Once the hangar is clear, secure it and tell the senior officer why.
2. Explain the science that justifies evacuation rather than simply opening the doors.
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Carbon monoxide is colourless and odourless, so the faint exhaust smell is not the indicator; it comes from other combustion products. CO binds haemoglobin far more readily than oxygen, forming carboxyhaemoglobin and reducing oxygen delivery. Early symptoms are headache, nausea and dizziness; confusion or drowsiness suggests significant exposure. A normal fuel-vapour reading on a detector with no CO sensor proves nothing. Evacuation is the right control because the source may still be present, the hangar is enclosed, and symptoms can worsen after exposure. 'Open the door' is an engineering control that depends on airflow and time; it does not protect the most exposed cadet. Fresh air and medical assessment are the primary controls, with atmospheric testing before re-entry. The science supports the judgement: remove people from the hazard first, then measure it.
3. How do you report the event and prevent recurrence?
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Report to the squadron duty officer and the safety officer as soon as the casualty is handed over. Give times, names, symptoms, actions, and the detector limitation. Log the event and preserve the hangar state for an investigation. Do not restart the engine or ground-run in that hangar until a calibrated CO check is satisfactory. Prevention: fit a CO detector or use a portable CO meter for ground runs; check exhaust extraction and door openings; brief the corporal and all cadets that 'just exhaust' can kill; add a ground-run checklist item; and rehearse the evacuation. The after-action review should ask why a fuel-vapour detector was accepted as a substitute for CO monitoring. The leadership point is that the junior cadet was right to challenge the corporal, and the organisation must make that challenge easy.