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 the ability of a combat aircrew to withstand high sustained G during air combat maneuvers [1]. Continue reading

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 the combat ready aircrew must remember those factors that lower one’s G tolerance, and must take precautions against the same. Continue reading

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 an aircrew whose G tolerance has been lowered due to prolonged break from combat flying, physiological factors or inadequate protection from conventional anti-G systems. However, no one is immune to G-LOC, irrespective of his flying experience. Continue reading

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”. Continue reading

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 flow, are the most important in turn determining the human tolerance to +Gz exposure. Continue reading

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, that the modern day combat aircraft are capable of, is G forces of 7G or more sustained for 15 seconds or more. Continue reading

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 to the magnitude and rapidity of changes in the position and attitude of the aircraft, in turn, compromising the human performance capability in the unnatural environment of military or aerobatic flying. Continue reading

G-LOC – Then and Now…

16 September 2011. Reno, Nevada saw the tragic crash of a P-51Mustang [1] during the Reno Air Races. The findings of the National Transportation Safety Board suggests that the pilot had lost consciousness due to ‘overwhelming’ G forces [2]. This occurrence in a modified 1940’s vintage aircraft is no surprise, considering its high thrust to weight ratios amongst its contemporaries, with a structural strength of -2G to +9G, making it likely that G induced loss of consciousness (G-LOC) could have been the cause of this tragedy, where besides the pilot, 10 spectators also perished [2, 3]. Continue reading

There is LASER in my eye!

There is a spurt in the incidence of Laser devices aimed at aircraft during low level flying or while making an approach to land [1, 2]. Despite punitive actions against culprits, including sentence up to 10 years in Germany or 20 years in US, it shows no signs of abating [2, 3, 4]. Those shining the handheld laser pointers into the aircraft cockpits are unaware that transient visual effects of laser are “a threat to safe aircraft operations”. This may also have a potential for permanent damage to the retina of aircrew [5].

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Pilot Incapacitation: Extent of the Problem.

The study by Evans et.al. highlighted a linear trend in incapacitation rates from the pilots in 20s to those in their 60s, with those in 60s accounting for 15% of incapacitation [4]. Both cardio- and cerebro-vascular conditions being responsible for 50% (18/36) of incapacitation events, including 2 of the 4 sudden deaths, endorse the present practice of screening for underlying coronary artery disease by aviation medical regulators the world over. However an interesting fact that emerged is the number of psychiatric episodes of incapacitation and impairment. Though not life threatening to the individual suffering from, say, panic attacks it is definitely a hazard for flight safety! Does it warrant that the regulators must pay increased attention to such maladies of the mind in the future? Continue reading