Medical perils of extending the range of single-aisle aircrafts

Single Aisle

The past decade has witnessed the introduction of new age technology aircraft engines. These engines are 12-15% fuel efficient and the airframe is lighter.

This has resulted in fuel efficiency and thus increased range of the aircrafts. Some of these aircrafts belong to the single aisle families of Airbus and Boeing.

This will be a shot in the arm for the aircraft manufacturers and the airlines who are already planning to introduce the opening of farther destinations.

However, there is a need to empathise with the plight of the passengers and crew. The physical movement of the crew is restricted in a single-aisle aircraft and with passenger seating over 180 passengers, it will be quite claustrophobic for many.

There are a number of medical conditions associated with long haul travel but most have not been proven with enough data.

World Health Organisation released research on Global Hazards of Travel (WRIGHT), in order to establish whether the risk of venous thromboembolism is increased by air travel, to determine the magnitude of the risk and the effect of other factors on the risk, and to study the effect of preventive measures.

The findings of the epidemiological studies indicate that the risk of venous thromboembolism is increased 2- to 3-fold after long-haul flights (more than 4 h) and also with other forms of travel involving prolonged seated immobility. The risk increases with the duration of travel and with multiple flights within a short period. In absolute terms, an average of 1 passenger in 6000 will suffer from venous thromboembolism after a long-haul flight.

Image result for long haul flying deep vein thrombosis
Medical conditions

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Enforced mobility

Data from the passenger survey shown in indicates the degree of enforced immobility experienced by many long-haul passengers.

Passenger mobility
The number of times the 310 respondents got out of their seat
during the flight

Just over 1/3 of passengers reported that they did not get out of their seat as many times as they would have liked during their flight. The main reason given was that the trolleys restricted any ability to move around the plane (i.e. to get to the toilet) (9% of all respondents). In addition, 25% of those respondents who were sat in either window or centre seats were unable to get out of their seat as often as they would have liked. These respondents felt that the presence of passengers in the seats next to them made it difficult to get out and many felt uncomfortable disturbing other passengers, particularly those sleeping.

Deep vein thrombosis

Image result for deep vein thrombosis

During the second world war, Simpson (1940) made the observation of an excess of deaths (6 fold) due to pulmonary embolus (PE) in those people spending prolonged time (>12 hours) in underground shelters in the UK. It soon became evident that a recurring theme to these deaths was the enforced immobility endured during these periods which were often repeated over successive nights.

The victims had often been sitting in deck chairs or similar seats. The realisation of the connection between prolonged sitting, probably with additional pressure on the leg veins caused by the structure of the seat, and PE resulted in the advice that people exposed to such prolonged confinement should be provided with bunk beds so that they could lie flat. Having done so the incidence of this condition declined.

Since this early report repeated reference has been made to the harmful effects of prolonged sitting with regards the formation of deep vein thrombosis (DVT).

Homans (1954) in 1954 presented 4 cases of travel/sitting thrombosis. Symington and Slack (1977) used the phrase ‘economy class’ syndrome alluding to the cramped conditions experienced by passengers in the economy section of aircraft but pointed out this syndrome was not restricted to this mode of transport alone.

Cruickshank et al (1988) reported 6 cases emphasising the role of air travel and thrombotic disease.

Cushion seat height

cushion seat height

An evaluation of seat cushion height was undertaken, by assessing the ability of passengers to place their feet fully on the floor while maintaining contact between seat backrest and their pelvis and spine. Table 12 shows 1st and 5th female and 95th and 99th %ile male sitting knee (popliteal) heights for British, European and World populations.

1st and 5th female and 95th and 99th %ile male sitting knee height

Ideally, the seat height would allow the maximum number of passengers to sit with their feet on the floor. However, when the anthropometric data above is compared with RVAR (DETR, 1998), PSV Accessibility Regulations (DETR, 1999) and previous aircraft seat recommendations, it can be seen that all the minimum recommended seat heights are between 30mm and 150mm (1.2″ and 5.9″) higher than the 1st %ile European female requires, increasing to between 60mm and 170mm (2.4″ and 6.7″) for the world population.

If the cushion is too high, smaller passengers cannot rest their feet on the ground, and consequently will experience tissue compression on the back of the thigh at the front edge of the cushion.

mindFly human factor Conclusion

A single aisle aircraft used on a flight over 4 hours can pose discomfort for the passengers and crew. The number of passengers counting over 180 can be a challenge for the crew. Their medical condition and the impact on flight operations will have to be considered by the operators. A relook at long term impact on the passenger health is imperative for the game changing strategy of long haul flying especially on single aisle aircrafts.

About Capt. Amit Singh

I think therefore I am Airlines Operations and Safety balance expert. A former head of operations/training and safety of successful LCC's in India. An experienced member of the startup teams of these airlines has hands-on experience in establishing airlines systems and processes.

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