Decompression Sickness in HA Reconnaissance Aircraft

Pilots flying high altitude (HA) reconnaissance sorties are vulnerable to decompression sickness (DCS) due to, exposure to “pressure equivalent up to 29,500 ft (8992 m) of altitude for over 8 h” [1]. Cruise altitude of such HA reconnaissance aircraft viz. U-2 [2] and MiG 25 [3] is 70,000 ft and 74,000 ft, respectively. There are two life support measures practiced to prevent DCS due to sudden decompression during HA missions [1]: pilots preoxygenate with 100% oxygen for a minimum of an hour prior to take-off, and don a pressure suit (Full pressure suit and partial pressure suit in U-2 and MiG-25, respectively). Jersey et. al., found that operationally there may be cases of joint pain reported but the severe form of DCS – pulmonary or neurological symptoms, were not found. They stated that 途etrospective surveys of U-2 pilots revealed widespread under-reporting…60-80% of respondents experienced DCS symptoms at some point in their careers, with 16-18% of these neurologic” [1].  Continue reading

Are SD accidents not so Common in Aviation?

Accidents due to Spatial Disorientation (SD), in military and general aviation, reportedly vary between 2.1 to 31% [1 – 11]. Despite of physiological limitations of the ‘human’ operator, accident statistics do not correctly reflect SD as a cause, as commonly as expected, especially in the military aviation. In fact, in a review of accidents due to SD, Gibb et. al. asserted “that SD contributes to at least 25-33% of all aircraft mishaps and it results in the highest number of fatalities [12]. Continue reading

Loss of Control: Human Factors in Air France Flight 447

Investigating the crash of Air France Flight 447 [1], from Rio de Janeiro to Paris, into the Atlantic Ocean on 01 June 2009, the French Bureau of Enquiry and Analysis for Civil Aviation Safety (BEA = Bureau d’Enquêtes et d’Analyses pour la Sécurité de l’Aviation Civile) released an interim report on 29 Jul 11. This report pertains to the emerging safety issues found in the wake of the crash, which resulted in tragic loss of all 216 passengers and 12 aircrew [2]. Continue reading

It Hurts in Flight – Barotrauma




Aero-odantalgia refers to symptoms related to various dental ailments due to change in ambient pressure in flight. It commonly presents as pain in tooth due to trapped air in a dental cavity after a filling has been done. Other reasons for dental pain could be due to infection of the gums or the root canal or even referred pain from maxillary sinus (Sinus Barotrauma).

Aero-odantalgia can be prevented by regular dental care and periodic dental check up.

Symptoms Due to expanding Intestinal Gases

The stomach and the intestines normally contain variable amount of gas. The quantity of gas depends upon the type of food consumed, its fermentation and digestion. During constipation or diarrhoea, the quantity of gas in the intestines may be more than what is normally present.

Obeying the Boyle’s Law, as the ambient pressure continues falling during ascent, the intestinal gas expands and gets expelled spontaneously at regular intervals. However, if the quantity is more or does not escape from natural orifices, one may suffer from abdominal distention and painful cramps. The discomfort may be tolerable at low altitude but can become severe at higher altitude. It is advisable to initiate descent, if the pain and discomfort is not relieved.

Adherence to the following habits may help reduce abdominal symptoms due to expanding intestinal gases in flight:-

  • It is advisable to cultivate regular eating habits.
  • One must avoid eating in a hurry.
  • It is safer to avoid certain foods which are known to produce more gas e.g. cabbage, cucumber, radish or any other food that may not ‘agree with you’.
  • Avoid chewing gum, since one tends to swallow more air while chewing it.
  • Aerated or carbonated drinks must not be consumed before flying.

Read More


1. Ernsting’s Aviation Medicine. Rainford DJ, Gradwell DP (Editors). 4th Edition. Hodder Arnold, London 2006.

2. Fundamentals of Aerospace Medicine. DeHart RL, Davis JR (Editors). 3rd Edition. Lippincott, Williams & Wilkins, Philadelphia 2002.

3. Human Performance & Limitations – JAA ATPL Theoretical Knowledge Manual. 2nd Edition. Jeppesen GmbH, Frankfurt 2001.

Acknowledgement  Image courtesy and Wikimedia Commons

It Hurts in Flight – Sinus Barotruama

Sinuses are small air filled spaces in the bones of the skull. These sinuses drain into the nasal cavity through small openings, which allow easy ventilation of air during ascent and descent.  Continue reading