LONG DURATION FIGHTER OPERATIONS WITH AIR-TO-AIR REFUELLING AND ITS
AERO-MEDICAL ASPECTS

INTRODUCTION

1. Air-to-Air refuelling ops are those which involve the transfer of fuel from one ac to another in flight. This extends the range, enables fighters to carry increased payload, increases the time on station and affords far greater flexibility in employment of aircraft. Air-to-Air refuelling can be used to enhance the capabilities of virtually all types of aircraft. The IAF has recently acquired air-to-air refuelling capability with the induction of IL-78 Flight Refuelling Aircraft (FRA) in its inventory.

2. The induction of the FRA would result in a considerable increase in the duration of fighter flights. Flights of fighter aircraft, which were earlier restricted to approx. 2 ½ to 3 hours, could now increase to 7 to 8 hours or even longer. Such long duration flights pose certain physiological difficulties and problems for fighter pilots of the IAF, who have so far not been exposed to such operations. Certain human frailties and physiological factors involved in these long duration fighter operations need to be understood by our fighter aircrew and they need to train to address the peculiarities arising thereof.

AIM

3. The aim of this paper is to identify the aero-medical aspects involved in long duration fighter operations resulting from air-to-air refuelling and suggest remedies for the same. It would also attempt to suggest modifications on the M-2000 ac to facilitate long duration operations.

AERO-MEDICAL ASPECTS OF LONG DURATION
FIGHTER FLIGHTS

4. Before examining the various human physiological factors and aero-medical aspects involved in long duration fighter operations, it is important to understand briefly as to how air-to-air refuelling has affected fighter operations.

Air-to-Air Refuelling and its Effect on Fighter Operations

5. Force Multiplier. Air-to-Air refuelling is a potent force multiplier i.e. it enhances the capabilities of virtually all aircraft resulting in an exponential increase in the options available in employment air power. The advantages accruing out of in-flight refuelling are increased range, increased endurance, response time, and increased flexibility.

6. Enhanced Flight Durations. A major limitation of fighter aircraft thus far, has been their limited fuel-carrying capacity. With air-to-air refuelling, this limitation is overcome. Availability of more fuel entails fighter ac carrying out long duration flights, much longer than what they are designed for. This does not impose any problems for the aircraft, but it certainly does impose various physiological problems for the aircrew operating them.

Aero-medical Aspects of Long Duration Flights

7. All civil aviation aircraft are multi-crew aircraft and are designed for long distance/ long duration flights. The availability of space and two pilots affords them the much-needed flexibility and hence the peculiarities of long duration flights do not impinge on them as adversely as they do on the fighter aircrew. Fighter aircrew are neither used to nor trained for flights exceeding duration of 2-3 hours. Long duration flights in fighter aircraft are thus inherently different from civil aviation and pose certain additional problems of limited movement, non-availability of toilet facilities, single cockpit crew, etc.

8. In long duration fighter flights certain human physiological factors – comprising aero-medical aspects – come into play which may affect the performance of aircrew. These physiological factors also finally become error-predisposing factors if not studied and trained for. The main aero-medical aspects of long duration fighter flights are:-

(a) Fatigue. The only major studies on fatigue in long duration flights subsequent to the Second World War were those carried out during the Berlin and Tokyo flights. In these studies it was identified that flights extending beyond six hours are more fatiguing than flights of shorter duration. Some personal variables, such as experience level of the pilot and complexity of the mission also induce fatigue in the pilots. Fatigue, generated by prolonged work, may seriously impair the efficiency of aircrew performance. This also results in a state of under-arousal in the aircrew which can have several consequences like attention failure, loss of speed and accuracy and inability to react to emergency situations.

(b) Boredom and Isolation. Single-crew long duration operations are ideal for inducing boredom and a feeling of isolation in the pilot. This in turn is likely to result in early symptoms of fatigue and lower level of alertness in cockpit, with same consequences as those in a state of under-arousal mentioned above.

(c) Lack of Movement. Unlike civil aviation aircraft, the pilot in fighter aircraft is strapped to his seat and stays so for the entire duration of his flight. Long-duration operations in such a condition are likely to affect the blood circulation of the pilot result in numbness of his body parts.

(d) Less Fluid and Food Intake. To prepare to undertake long duration operations, fighter aircrew at times drastically reduce their fluid and food intake prior to, and during, such flights. However, in extreme cases this might cause:-

(i) Dehydration. The effects of dehydration on the human body are well known and well-documented. To avoid the need to urinate during flight, if a pilot stops his fluid intake much before and during the flight, there are chances that he might get dehydrated. 5-10% water loss as a percentage of body weight might show up as slowness of movement, dryness of mouth, dizziness, headaches and shortness of breath.

(ii) Hypoglycaemia. No food intake or reduced food intake much prior to long-duration flights is likely to result in hypoglycaemia or lowered blood glucose levels. The importance of adequate blood sugar level for flying operations is well known to all aircrew. It results in sweating, palpitations, disorientation and headache.

(e) Spatial Disorientation. Longer the duration of the flight, greater are the chances of pilot encountering various types of in-flight conditions. These in-flight conditions might vary from clear skies with good horizon to cloudy/ hazy skies with unclear horizon. Therefore, there are greater chances of pilot experiencing spatial disorientation if the pilot is not prepared or trained for. Also, the effects of fatigue, boredom, feeling of isolation and lowered level of alertness is likely to add to pilot getting disoriented during such flights.

(f) Inability to Defecate/ Urinate. Considering the extended duration of these flights, the possibility of pilots developing an urge to urinate, or even defecate, can not be ruled out. However, in fighter aircraft, unlike transport or passenger aircraft, facility to relieve such an urge does not exist. Continuing flight operations without relieving such an urge will cause distraction and/or lack of attention.

Suggested Remedies

9. With the knowledge of these aspects, it is imperative that fighter aircrew devise remedies to overcome them. A few remedies to overcome the adverse effects of these aero-medical aspects are discussed in the following paragraphs.

10. Systematic Training. In civil aviation operations, aircrew are trained to overcome the human factors involved in long duration flights. And after undertaking such flights on regular basis, they get accustomed and adapt to them. But such is not the case with fighter aircrew. They are neither trained nor used to long duration operations. Therefore, they lack the awareness of these human factors, which comprise aero-medical aspects of long duration flights. Since in-flight refuelling in fighter operations will gradually become an integral part of IAF operations, fighter aircrew need to be systematically trained for such operations and made aware of the peculiarities arising out of such operations.

11. Adequate Sleep. Adequate and uninterrupted sleep is necessary for performing all aviation related tasks and this is especially important prior to undertaking long-duration operations. It is also important to remember that adverse effects of sleep loss are cumulative. It should be emphasized to all fighter aircrew, likely to undertake long duration operations, that they should not undertake such operations without adequate and proper sleep.

12. Strict Adherence to Rules. All pilots must understand and strictly adhere to rules pertaining to duration of rest between two duty periods. Organisation must encourage pilots to follow such laid down rules and orders.

13. Rest and Relaxation. Since the best antidote to fatigue is rest and relaxation, the organization and pilots themselves must ensure availability of appropriate environment at work and home. Pilots must be fully rested and absolutely relaxed prior to such flights. Pilots must utilise the available rest periods properly.

14. Self Discipline. The importance of self discipline in any sphere of life cannot be overemphasized, particularly in aviation. Pilots must be self disciplined in getting adequate sleep and reducing alcoholic intake as these lead to early fatigue during flights. They must also make all efforts to stay physically fit.

15. Reduced Food and Fluid Intake. 2-3 hours prior to such flights, pilots should reduce food and fluid intake. This will reduce the chances of developing an urge to urinate during long duration flights. However, to prevent getting dehydrated small quantities of fluids should be consumed as and when required, during the sorties.

16. Provision of Water and Food in the Cockpit. Provision should be made to store water and food in the cockpit to be consumed by the pilot if required to counter the effects of dehydration or hunger.

17. Dual-Crew Fighter Aircraft. Boredom and feeling of isolation can be countered by undertaking such ops in fighter aircraft which can carry at least two pilots. Communication between the two pilots at regular intervals will keep them alert and attentive.

18. Provision of Facility to Urinate. All modern day fighter aircraft are being designed with this facility as a part of their design feature in view of the increased reliance on air-to-air refuelling for fighter operations in the days to come. However, for older generation aircraft which are being modified to undertake such operations without this facility, a provision should be made in the cockpit which will enable pilots to urinate if required.

Suggested Modifications in M –2000 for Long Duration Flights

19. A study of the M-2000 has been carried out at 40 Wg, AF to suggest modifications to the aircraft and the requirement of certain facilities for the aircrew to undertake long duration flights, keeping in mind the above mentioned aero-medical aspects. These are:-

(a) Urine Bags. Urine bags, similar to the ones used by French Air Force pilots, be provided for such flights since there is no possibility to extravasate wastes in M-2000 ac. This bag is made of water absorbing flexible material and is self sealing. It is used by the pilot to urinate into. After use it can be folded and kept in the G-suit pocket.

(b) Stowage Compartments for Eatables and Drinks. The space available on the starboard horizontal console, behind the CB panel in the cockpit, can be utilised for providing a stowage compartment for storing eatables and water bottles for such flights.

(c) R/T Frequency for Communication within Formation Members. The M-2000 has an additional UHF R/T set, an R/T frequency needs to be identified for general communication between the formation members. This will assist in overcoming boredom and keep the pilots alert.

CONCLUSION

20. Gradually, most of the fighter operations in IAF will become largely dependent on or get linked to air-to-air refuelling, entailing fighter fights of long durations. Therefore, there is an urgent need to disseminate the knowledge of aero-medical aspects involved in long duration fighter operations among the fighter aircrew. Various human physiological factors which comprise these aero-medical aspects like fatigue, lack of sleep, spatial disorientation can lead to errors and accidents. These cannot be wished away. The awareness of these factors and adequate training to overcome their adverse effects, coupled with caution and self discipline, can ensure that fighter aircrew undertake long duration mission safely and efficiently.

RECOMMENDATIONS

21. In view of the importance of understanding and overcoming the aero-medical aspects involved in conduct of long duration fighter flights for safe operations, the following are recommended:-

(a) Aircrew Training. All fighter aircrew involved in missions involving air-to-air refuelling need to be made fully aware of various aero-medical aspects involved and trained to overcome their adverse effects.

(b) Suggested Modifications on Mirage-2000 Aircraft. All efforts should be made to implement/provide the suggested modifications/ provisions on M-2000 aircraft at the earliest. They will go a long way in making these operations safer and more efficient.

(c) Involvement of Institute of Aerospace Medicine, IAF. This institute should be tasked to undertake a detailed study of aero-medical aspects of such operations, educate aircrew about the effects involved, and develop training programmes to overcome the adverse effects and facilitate safe operations.