Decompression Sickness in Pilots

What Causes Decompression Sickness in Aviation?

Decompression sickness (DCS) in aviation occurs when a pilot is exposed to a rapid drop in cabin pressure at high altitude. Under normal pressure, nitrogen is dissolved harmlessly in body tissues. If pressure drops quickly, nitrogen forms bubbles in tissues and blood, leading to symptoms. This risk increases with altitude, duration of exposure, age, body mass, and especially after recent scuba diving.

Typical Symptoms in Pilots

DCS presents with a range of symptoms, which may appear during or even hours after flight:

• The bends: Severe joint and muscle pain
• The creeps: Skin itching or rash
• The chokes: Chest pain and breathing difficulty
• The staggers: Dizziness, unsteadiness, collapse, or even unconsciousness Other signs include numbness, weakness, visual disturbances, and fatigue.

Prevention Strategies

• Maintain cabin altitudes below 18,000 ft; most commercial aircraft keep cabin altitude between 6,000–8,000 ft.
• Strictly avoid flying within 24 hours of scuba diving (or 12 hours for shallow dives).
• Stay physically fit and avoid risk factors like smoking and obesity.

Immediate Actions for Crew

If DCS symptoms develop in flight:

• Don oxygen masks immediately
• Initiate an emergency descent to the lowest safe altitude
• Land as soon as possible
• Do not fly again for at least 24 hours
• Seek urgent medical evaluation; recompression therapy may be required

Special Considerations

Symptoms can be delayed—sometimes appearing up to 24 hours after exposure. Even if no symptoms are present after a decompression event, medical clearance is required before returning to flying duties. Note that otic (ear) barotrauma can worsen during descent due to trapped air expanding in the middle ear, causing pain or hearing issues.