Category Archive: Human Physiology

Who failed in Crash of Flight IX-812?

The report on accident of Air India Express Flight IX-812 highlighted several factors which resulted in the tragic loss of 158 lives [1]. Limiting to the human factors alone, there were both physiological limitations of the crew and failure of crew resource management (CRM), besides organisational shortcomings.

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Fatigued Pilots! What Happened to Flight IX-812

Air India’s low cost airline, Air India Express, operates a scheduled Quick Turn Around flight IX-811/812 on Mangalore-Dubai-Managlore sector. The onward flight from Mangalore is at 21:35 H (IST) while the return from Dubai is scheduled at 02:45 H (IST, local time 01:15 H), to arrive at Managlore at 06:30 H (IST). On 22 May …

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Tired eh! Physical Cost of AGSM

Fatigue is the cost of correctly performed Anti-G straining manoeuvre (AGSM) to fight against the +Gz forces during air combat. Being an isometric exercise, akin to a 50 or 100 m race or weight lifting, the muscles maintain sustained contraction during AGSM to generate energy anaerobically. Thus time “to fatigue” and of “fatigue recovery” determine …

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Protection against the ‘G’

Average relaxed ‘G’ tolerance of combat aircrew varies between 4 to 5G, although the range may be 3 to 8G. Yet, one must note there are large individual variations in G tolerance and even in the same individual, the tolerance may vary on different days or different times of the day. It is here that …

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G-LOC Demystified

G-LOC has been implicated in various combat aircraft mishaps. Incidence of in-flight G-LOC in India is 11%, while it is 12 and 19% in USAF and RAF, respectively. Interestingly, G-LOC is more likely to occur in a trainee pilot, co-pilot or weapon system operator, who is caught unaware by the sudden onset of G or …

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G-LOC – The Enemy within!

G-LOC is G-induced loss of consciousness, defined as a “state of altered perception wherein one’s awareness of reality is absent as a result of sudden, critical reduction of cerebral circulation caused by increased G force”.

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Air Combat Manoeuvres and +Gz Forces

During air combat manoeuvres* or while practicing basic fighter manoeuvres**, the pilots are exposed to the commonest type of acceleration encountered in aviation – +Gz. Interestingly, the aircraft are capable of pulling higher Gs and sustain it longer than an unprotected human being can tolerate. The effects of +Gz on the circulatory system, and in turn the blood …

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G Force – What is?

‘G’ is the ratio between a given acceleration and the acceleration due to gravity. The term ‘G force’ is used sometimes to describe a force, which produced acceleration, which is a multiple of the acceleration due to gravity (9.81 m/sq sec). Thus, an acceleration of 98.1 m/sq sec would be 10 G. High sustained G, …

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Exhilarating when Accelerating in Air!

A fast jet can move rapidly on ground, taking off into the medium of air where it can be manoeuvered in flight by the aerodynamic forces generated by the thrust of its engine and manoeuvrability by swift-responding control surfaces. Such movements of the aircraft affect its occupants, the aircrew (pilots and weapons system operators) due …

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Hypoxia Training – Essentially Useful.

Most military aircrew undergo hypoxia training, including experience in decompression chamber, to understand the ill-effects of the silent but deadly hazard of in-flight hypoxia [1]. Symptoms experienced during the classic mask-off hypoxia indoctrination in altitude/decompression chamber correlates well with reported in-flight symptoms [2]. The objectives of hypoxia indoctrination, an effects-based training, is to make aircrew …

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