Fatica da volo, tempi di impiego, memoria, sesso dei piloti.
Una panoramica su temi collegati

Fatigue in Transportation: Physiological, Performance, and Safety Issues
by Mark R. Rosekind April 1999
Alertness Solutions
Introduction
Maintaining safe transportation operations is a complex task. The undertaking must address a range of issues from the functioning of large systems to the individual human operator.
For the foreseeable future, the human operator (pilot, driver, maintenance person, etc.), remains central to safe, efficient, and reliable transportation activities.
Therefore, the importance of addressing human-related error, which accounts for at least 70% of transportation accidents, remains critical to maintaining and improving safety.
Fatigue, sleep loss, and circadian disruption created by transportation operations can degrade performance, alertness and safety.
An extensive scientific literature exists that provides important physiological information about the human operator, which can be used to guide operations and policy. For example, there are human physiological requirements for sleep, predictable effects of sleep loss on performance and alertness, and patterns for recovery from sleep loss. Additionally, the circadian clock is a powerful modulator of human performance and alertness, and in transportation operations, it can be disrupted by night work, time zone changes, and day/night duty shifts. Scientific examination of these physiological considerations has documented a direct relationship to errors, accidents, and safety. This scientific information can provide important input to policy and regulatory considerations.
Managing fatigue in the complex and diverse transportation environment requires an integrated and multi-component approach. The complexity and diversity of operational requirements preclude a simple solution, and managing fatigue will benefit from addressing education, hours of service, strategies, technology, design, and research. The transportation industry has established a strong safety record by identifying and proactively addressing both substantiated and potential risks. Effectively managing fatigue in transportation operations offers the opportunity to further reduce risks and improve safety. This overview provides an introduction to the scientific foundation that exists regarding the physiology of and performance related to fatigue in transportation. It also examines the human physiological requirement for sleep and the functioning of the circadian clock.

The Biological Imperative: Human Sleep Need and the Circadian Clock Human Sleep Requirements
Sleep is a vital physiological function. Historically, sleep has been viewed as a state when the human organism is turned off. However, scientific findings have clearly established that sleep is a complex, active physiological state that comprises different stages. On average, most people physiologically require about 8 hrs of sleep per night.
When provided adequate time to sleep, humans can average about 8.25 to 8.5 hrs of phys-iological sleep. Laboratory studies use physiological measures (i.e., brain, eye, and muscle activity) of sleep quantity and quality and daytime sleepiness to determine the number of hours of sleep that provide an optimal level of waking alertness. It is important to distinguish this physiologically determined sleep requirement from both habitual and reported sleep amounts. Some studies have examined the reported amount of habitual sleep over time and other studies have collected one-time surveys inquiring about average sleep amounts. Overall, most adults report an average of about 7–7.5 hrs sleep per night. However, data obtained in controlled laboratory settings challenge whether this "reported" amount of sleep is sufficient for optimal levels of waking alertness. Studies have demonstrated that extending sleep beyond the reported 7–7.5 hrs of "usual" sleep significantly increases daytime alertness. The National Sleep Foundation commissioned a Gallop survey examining the report of daytime sleepiness in a random sample of 1,001 individuals. The findings demonstrated that 75% reported daytime sleepiness, with 32% of these reporting severe levels. Thirty-two percent reported that their sleepiness interfered with activities and 82% of the respondents believe that daytime sleepiness has a negative effect on their productivity.
These amounts are averages and there are individuals at both extremes of short and long sleep requirements. These sleep requirements change significantly with age.
Younger individuals require more total sleep and this amount decreases to that needed by adults (although it is not the case that older people need less sleep than other adults). Sleep structure also changes with age (e.g., less deep sleep, more awakenings in older adults).
In summary, humans physiologically require about 8 hrs of sleep, though they report usual sleep amounts of about 7–7.5 hrs. A majority of the adult population report daytime sleep-iness, and when sleep is extended, there is a significant increase in alertness.

Effects of Sleep Loss
Sleep loss is common and can be acute or cumulative. In an acute situation, sleep loss can occur either totally or as a partial loss. Total sleep loss involves a completely missed sleep opportunity and continuous wakefulness for about 24 hrs or longer. Partial sleep loss occurs when sleep is obtained within a 24-hr period but in an amount that is reduced from the physiologically required amount or habitual total. Sleep loss also can accumulate over time into a "sleep debt." For example, an individual who requires 8 hours of sleep and obtains only 6 hours is essentially sleep deprived by 2 hours. If the individual sleeps only 6 hours over 4 consecutive nights, then the 2-hour-per-night sleep loss would accumulate into an 8 hour sleep debt. Sleep loss, whether total or partial acute or cumula-tive, results in significantly degraded performance, alertness, and mood.
The reduced human performance capability that results from total sleep loss is well documented. However, perhaps the most common occurrences in transportation operations are acute partial sleep loss and accumulation of a sleep debt. A review of the relevant scientific literature indicates that as little as two hours of sleep loss on just one occurrence can result in "impairment of performance and levels of alertness".
Therefore, an average individual with a physiological requirement of 8 hours sleep who obtains only 6 hrs of sleep may demonstrate significantly degraded waking performance and alertness. Cumulative sleep debt also significantly reduces alertness and performance. Studies have demonstrated that not only does the sleep loss accumulate but that the negative effects on waking performance and alertness also are cumulative and increase over time. Performance decrements due to sleep loss can occur across diverse functions. For example, studies have demonstrated slowed reaction time, reduced vigilance, cognitive slowing, memory problems, time-on-task decrements, and optimum response decrements. Performance variability also increases with sleep loss. Therefore, overall performance can be significantly reduced with an increased variability or unevenness in responding. Consider that these findings occur in some of the simplest performance challenges, such as reaction time to a single stimulus or minimal choice memory task. These basic psychomotor and cognitive functions are the foundation for any task requiring complex, higher-order performance.
An important phenomenon, highly relevant to operational environments, is that there is a discrepancy between the subjective report of sleepiness/alertness and physiological measures. In general, individuals will report higher levels of alertness than indicated by physiological measures. Data from an international study of flight crews had an example where the highest subjective rating of alertness occurred at a time when physiologically the individual was falling asleep within 6 minutes (an indicator of severe sleepiness).
Likewise, subjective and physiological self-assessment of perfor-mance can differ significantly. The operational relevance of this phenomenon is clear. For example, an individual might report a low level of sleepiness or fatigue but could be carrying an accumulated sleep debt with a high level of associated physiological sleepiness. This individual, in an environment stripped of factors that conceal the underlying physiological sleepiness, would be susceptible to the occurrence of spontaneous, uncontrolled sleep episodes and to the performance decrements associated with sleep loss.

Recovery from Sleep Loss
When determining requirements for providing a recovery opportunity from sleep loss, two factors should be considered. First, when does the internal sleep architecture return to usual levels? Second, when do waking performance and alertness levels return totheir baseline? After sleep loss, recovery is not accomplished through an hour-for-hour restitution. Even after extremely prolonged wakefulness, initial recovery sleep may last only 12–15 hrs. Rather, recovery is accomplished through an increase in deep sleep (Non-Rapid-Eye-Movement or NREM slow wave sleep) observed starting on the first night of regular sleep. Generally, two nights of recovery sleep (slightly longer than an average night’s sleep) are needed to resume a normal baseline sleep pattern, though this can be dependent on the duration of the continuous wakefulness.
Also, typically, two nights of recovery sleep are needed to return to a normal baseline of waking performance and alertness, though this too can be dependent on the length of prior wakefulness.

The Circadian Clock
Besides sleep, the other major physiologic determinant of waking performance and alertness is the internal circadian clock. Circadian (circa = around, dies = day) rhythms fluctuate on a 24-hr cycle with peaks and troughs occurring in a regular pat-tern. These patterns are controlled by a circadian pacemaker located in the suprachiasmatic nucleus (SCN) in the brain. The SCN is the circadian timekeeper for a wide range of human functions. One of the most prominent is the 24-hr sleep/wake cycle programmed for a daytime period of consolidated wakefulness and a nighttime period of consolidated sleep. There are circadian patterns for cognitive and psychomotor performance, physiological activity (e.g., digestion, immune function, thermoregulation, DNA synthesis), alertness, and mood. Even birth and death have circadian patterns that peak during the night.
Body temperature is often used as a marker of the internal circadian clock (some-times referred to as the "hands of the clock"). The trough or low point of the clock is around 3 am to 5 am, with many functions demonstrating reduced levels from 12 am to 6 am. The lowest level of function (e.g., alertness, performance, subjective mood, temperature) occur within the 3 am to 5 am trough. Sleepiness has bimodal distribution (i.e., two peaks and two troughs each day), being most severe at 3 am to 5 am with a less marked but significant expression between roughly 3 pm to 5 pm. This afternoon increase in sleepiness occurs whether or not a meal has been consumed, though the meal may exacerbate the underlying sleepiness.
Zeitgebers ("time givers") are cues that synchronize circadian rhythms to their 24-hr pattern. To date, light has been demonstrated to be among the most powerful zeitgebers to synchronize the circadian pacemaker. Bright light can dramatically shift the phase of the human circadian clock when applied at responsive times in the 24-hr cycle. Without cues, the intrinsic rhythm of the clock is longer than 24 hrs. Generally, data have demonstrated a free-running pattern approximating 24.9 hrs, though recent findings suggest this may be closer to 24.2 hrs. An intrinsic period longer than 24 hrs provides an inherent tendency to support circadian delays (e.g., staying awake longer) and to oppose advances (e.g., trying to go to sleep earlier).
Moving to a new light/dark schedule, such as a shift to nightwork or a time zone change, can create internal and external desynchronization. These involve an internaldesynchrony among circadian rhythms and a discrepancy between internal circadian timing and external/environmental cues, respectively. The internal clock can take from several days to weeks for adjustment or, in some circumstances, not fully resynchronize at all. Scientific studies have demonstrated these findings in the laboratory and in field studies conducted during actual transportation operations.

Pilots Welcome FAA Enforcement Of Pilot Fatigue Rules
May 20, 2001
The Coalition of Airline Pilots Associations described the Federal Aviation Administration (FAA) decision to enforce existing rules designed to avoid pilot fatigue as a "small step in the right direction."
The rule specifically requires that a pilot must have at least eight hours of rest within any 24-hour period and, therefore, cannot be forced to be on duty for more than 16 hours each day.
Captain Bob Miller, President of the Coalition of Airline Pilots Associations, said about enforcement of the 16-hour rule: "While we are pleased to see that the FAA at long last is heeding the calls of pilots to enforce a rule that has been on the books since 1985, their decision is only the first of many steps required to address the growing concerns of pilot fatigue.
"Furthermore, the fact that the industry is being given an additional six months to comply with a law that has been in existence for over 15 years is troubling.
"The FAA's treatment of this issue only underscores the imperative of the agency to deliver on its commitment of a broader, more comprehensive review of outdated flight and duty time standards. Aviation experts have continuously pointed to the growing problem of pilot fatigue, and there has been much discussion about the need to adopt more modern standards that fit the circumstances of air travel in the 21st century.
"Numerous scientific studies have quantified more precisely the effects of fatigue on performance, and identified particular dangers associated with night or "back side of the clock" flying. Furthermore, pilot fatigue has been a contributing cause to countless aircraft mishaps since the ruling.
"Clearly, deciding to enforce rules already in existence is a positive step, but falls considerably short of fully addressing the underlying concern voiced by thousands of pilots, as well as scientists, aviation experts, Members of Congress and others.
"It is critical to the safety of millions of passengers that the FAA's efforts to prevent pilot fatigue not stop with this statement. Otherwise, today's announcement will only have a small impact on the greater problem of pilot fatigue."
Enforcement of this rule has been part of a long-standing debate about the need to update rules and regulations that protect against pilot fatigue and better reflect the circumstances associated with modern air travel. It is also the source of a petition filed in federal court earlier this year by CAPA seeking to have the U.S. Court of Appeals for the District of Columbia intervene in this matter on behalf of pilots.
CAPA is a trade association that operates on a consensus basis to address issues of concern to professional airline pilots. Its members include the Allied Pilots Association (American Airlines), FedEx Pilots Association, Independent Pilots Association (UPS), Southwest Airlines Pilots Association, the International Brotherhood of Teamsters Airline Division, and International Brotherhood of Teamsters Local 1224, which represents Airborne Express pilots. CAPA member groups represent a total of 26,500 pilots.

Ritirata la circolare sui limiti di impiego dei piloti
(Air Press - Maggio 2001)
È stata "congelata" la circolare con la quale l’Enac, o meglio, il Dipartimento Sicurezza dell’ente, intendeva "riformare" i limiti di impiego degli equipaggi di condotta, «correttamente reinterpretando», ma sostanzialmente rivoluzionando la norma attuale imponendo ai vettori, nel termine di pochi giorni, di rafforzare con un pilota extra gli equipaggi degli aerei che svolgevano una attività fino 13 ore di volo giornaliere. La norma, come si può bene immaginare, aveva sollevato una decisa protesta da parte di gran parte degli operatori (cfr. AIR PRESS, Fasc. 20/01, pag.792) che si erano rivolti alla loro organizzazione di rappresentanza, la Assaero, che è riuscita ad ottenere dall’Enac la sospensione del provvedimento. Ora si attende il termine di fine luglio, stabilito dall’Enac, per attivare un processo condiviso ente-sindacati piloti-associazioni datoriali, per arrivare all’eventuale elaborazione di una nuova normativa. Come sia potuta uscire dall’Enac una norma così dirompente non è chiaro. Tra l’altro - hanno fatto notare gli operatori all’ente e molti anche all’interno dell’organismo ne erano coscienti - non è possibile modificare una circolare ministeriale pubblicata sulla Gazzetta Ufficiale con una semplice circolare inviata agli operatori. Ma più che l’aspetto puramente formale, resta il merito di un provvedimento che avrebbe avuto pesantissime conseguenze sia operative che economiche sull’attività di quasi tutte le compagnie aeree e che dunque sembrava strano che potesse essere di semplice competenza di un dipartimento che di sola sicurezza si occupa. Un provvedimento di seria riforma dei limiti di impiego del personale di volo - semmai si dovesse veramente rendere necessario - non può infatti prescindere da una seria ricerca scientifica di base, da una valutazione di tutte le implicazioni operative e giuridiche ed anche quelle economiche, cioè un provvedimento con una origine "multidisciplinare" frutto dello stretto coordinamento tra più funzioni dell’Enac, cosa che è mancata del tutto nel provvedimento citato, nato nell’ambito di un apposito gruppo di lavoro costituito dall’Enac con i soli rappresentanti dei sindacati dei piloti ed in particolare da una decisa sollecitazione di uno di essi, la UP, che lo ha visto come uno strumento di rivendicazione nei confronti di alcuni operatori nazionali ed era interessata - è stato detto dalla UP ad AIR PRESS - «ad evitare il dumping del mercato del lavoro dei piloti». In pratica l’obiettivo è quello di imporre i limiti aziendali Alitalia, e dunque i costi Alitalia, a tutte le altre compagnie aeree nazionali. Probabilmente a fine anno la questione sarà più chiara. Infatti per quella data dovrebbe essere completato lo studio in corso da tempo da parte della FAA negli Stati Uniti, che ha annunciato che vuole rivedere i limiti di impiego a seguito di nuove evidenze sugli studi sulla fatica dei piloti, e quello europeo, condotto in ambito JAA, che oltre ad una raccomandazione di tipo tecnico, nel 2002 potrebbe anche portare ad una direttiva o ad un regolamento comunitario.

Il periodo in grassetto lo abbiamo evidenziato perché riteniamo allarmante l'approccio di chi ha scritto l'articolo e quindi di Air Press. Appare sbilanciato in una difesa d'ufficio di certi interessi ed è una critica sarcastica a certe supposte o evidenti ingenuità procedurali del Dipartimento Sicurezza dell'ente.
Chi si occupa di sicurezza all'interno dell'ENAC dovrebbe essere istituzionalmente il riferimento filosofico e di policy di tutto l'Ente.
Dal momento che si è ritenuto necessario inserire nell'Ente un professionista con esperienza di Comandante di B747, di istruttore e controllore, di vicecapopilota di tre tipi di aeromobili e capopilota di B747, che ha avuto l'incarico di Direttore Operazioni Volo della Compagnia di Bandiera e che ha fatto parte di Commissioni di inchiesta di incidente, oltre ad essere stato membro della pattuglia acrobatica nazionale [ma questo può essere marginale come il fatto che, lui sì, è nato Imparato], è evidente che quanto possa scaturire da cotanta fonte in materia di sicurezza debba essere preso almeno in considerazione.
Condividiamo che sulle norme sui limiti di impiego, nessuno deve avere "volpi sotto al braccio" e che la norma deve esprimere un criterio più che dei numeri, una filosofia che, riconoscendo l'autonomia finale del comandante in ordine a valutazioni di sicurezza deve essere guida e garanzia per tutti.
Le negoziazioni contrattuali devono avvenire su altri tavoli e tra altri interlocutori.
In ogni caso si consideri che gli utenti non pensano certo di risparmiare sul biglietto per volare con piloti utilizzati in modo più intenso o provatamente suscettibili a fatica a causa dei tempi di impiego.

Jet Lag Shrinks The Brain And Leads To Memory Loss
May 21, 2001

Researchers in the United Kingdom say that a study of airline cabin crews has revealed that frequent jet lag can shrink the brain.
The research team at the University of Bristol found that temporal lobe regions of the brain critical to memory became smaller after five years of regular jet lag exposure.
The effect was accompanied by memory impairment and high levels of the stress hormone cortisol.
Crew members with similar amounts of flight time, but who had longer intervals between long haul trips, did not suffer the same way.
The findings were said to have broad implications not just for airline staff, but also for shift workers and parents of young children whose body clocks are disturbed during the night.
It was not known how long the brain changes persisted, or whether they were reversible.
Evidence of impaired thinking ability in cabin crews subjected to repeated jet lag had already emerged in a previous study by the same research team from the University of Bristol.
For the new study, Kwangwook Cho's team at the university medical school, used magnetic resonance imaging to measure brain volumes.
The scientists, who tested 20 women employed by international airlines, wrote in the journal Nature Neuroscience: "Salivary cortisol levels in cabin crew after repeated exposure to jet lag were significantly higher than after short distance flights, and the higher cortisol levels were associated with cognitive deficits. "The present study demonstrates that significant prolonged cortisol elevations produced reduced temporal lobe volume and deficits in spatial learning and memory."

Dal notiziario di Le Scienze
22.05.2001

Il cervello si ritira
Tra i problemi connessi al jet lag cronico, anche perdita della memoria e disordini mentali
Secondo uno studio pubblicato su «Nature Neuroscience», il jet lag cronico può causare un vero e proprio restringimento del cervello, che porta a disordini mentali, tra cui la perdita della memoria. Nello studio, i ricercatori dell'Università di Bristol hanno confrontato le dimensioni dei lobi temporali del cervello di due gruppi di assistenti di volo, a cui erano stati concessi tempi diversi per recuperare dal jet lag. Il jet lag è una condizione tipica di cui soffrono alcune persone quando viaggiano attraverso molti fusi orari, ed è caratterizzato da fatica, disorientamento e disordini del sonno.
Il gruppo di soggetti in esame comprendeva 20 donne, di età compresa fra i 22 e i 28 anni, che avevano tutte almeno cinque anni di carriera alle spalle e attraversavano normalmente per lavoro almeno sette fusi orari. Nello studio non sono stati inclusi uomini per il semplice motivo che essi sembrano soffrire meno del jet lag.
In particolare, lo studio ha verificato gravi deficit nelle attività svolte dal lobo temporale destro, che si occupa, tra le altre cose, del riconoscimento visivo e della memoria spaziale. I ricercatori hanno verificato, usando tecniche di risonanza magnetica, che le assistenti di volo che avevano a disposizione meno tempo per riprendersi avevano lobi temporali destri in media leggermente più piccoli. A questo «restringimento» corrisponde anche un deterioramento della memoria a breve termine, che è stata misurata chiedendo ai soggetti di ricordare la disposizione di alcuni punti su uno schermo a distanza di qualche decina di minuti. Gli scienziati non hanno trovato deficit nel linguaggio, che è controllato invece dal lobo sinistro.
Lo studio potrebbe avere implicazioni importanti non solo per gli assistenti di volo, ma anche, per esempio, per i genitori di bambini molto piccoli, che spesso hanno i ritmi circadiani sconvolti. Il risultato pratico dello studio è infatti che i rapidi cambiamenti dei ritmi circadiani hanno un effetto dannoso sul cervello, indipendentemente dalla loro causa.

Dal notiziario di Le Scienze
22.05.2001
Il sesso dei piloti
Gli uomini, in generale, sono sembrati più portati a prendere decisioni sbagliate o correre rischi inutili
Uno studio pubblicato sul numero di maggio di «Aviation, Space, and Environmental Medicine» rivela che negli Stati Uniti gli incidenti che avvengono nell'aviazione da diporto vengono causati da uomini e donne in modo diverso. I piloti uomini tendono infatti ad avere incidenti per colpa della disattenzione, o per decisioni sbagliate, mentre le donne sono più propense a compiere errori di pilotaggio veri e propri. Gli incidenti nell'aviazione da diporto rappresentano circa l'85 per cento di tutte le morti che avvengono in incidenti aerei negli Stati Uniti. Poiché l'inesperienza e la giovane età sono fattori che contribuiscono agli incidenti, Susan P. Baker, della Johns Hopkins University, autrice del lavoro, spiega che lo studio si è concentrato sui piloti maturi.
I ricercatori hanno estratto i loro dati da un progetto di ricerca più vasto sull'invecchiamento dei piloti e la sicurezza. I dati sono stati raccolti da incidenti di aerei ed elicotteri avvenuti fra il 1983 e il 1997, che hanno coinvolto 144 uomini e 287 donne di età compresa fra i 40 e i 60 anni.
I ricercatori hanno così scoperto che la perdita di controllo in decollo o in atterraggio sono gli incidenti più comuni, che rappresentano il 59 per cento degli incidenti delle donne e il 36 per cento di quelli degli uomini. Per gli uomini, seguono i guasti meccanici, rimanere senza carburante e atterrare con il carrello alzato erano tra le cause più frequenti per gli uomini, mentre per le donne sono gli stalli a rappresentare un problema.
La maggior parte degli incidenti, il 95 per cento per gli uomini e l'88 per cento per le donne, hanno coinvolto almeno un errore del pilota. Un uso scorretto del timone, una risposta lenta a un rimbalzo o l'incapacità di recuperare da uno stallo erano le cause più comuni per entrambi i sessi, ma prevalenti fra le donne. Gli uomini, tuttavia, sono sembrati più portati a prendere decisioni sbagliate o correre rischi inutili, come volare con il brutto tempo o su un aereo con problemi noti.
In pratica, le donne, anche se più portate a perdere il controllo, sono risultate in genere più prudenti.

Air Quality In Aircraft Cabins Can Spread Diseases
Sep 4, 2001 (Airwise - news)
Poor air quality in passenger aircraft is leading to the spread of diseases and particularly TB, a leading academic claims.
Professor Martin Hocking told a London conference that some aircraft are operating with oxygen concentrations below the legal working environment requirement.
He said he had evidence that the oxygen concentration in aircraft is only 79% of the American legal requirement for working environments.
"The risk of exposure to airborne diseases during air travel is often underestimated," said Professor Hocking, of the University of Victoria, Canada.
"Viral infections such as the common cold, influenza, measles, mumps and chicken pox are easily spread.
"More worryingly, there have been well documented cases of TB transmission, a significant risk to air travelers when it is realised that this disease is endemic in many parts of the world, and that single or multi-drug resistant varieties have shown up in increasing frequency in recent years."
It is known that oxygen deficiency can lead to fainting episodes in adults and can contribute to the risk of death in very young infants.