# Presentation: 693708

## Effects of 18-Hour Flights on Crew Alertness and Performance

- Fatigue Countermeasures Group
- Human Factors Research and Technology Division
- NASA Ames Research Center

## Aircrew Fatigue is a Significant Problem

- Long-haul flights across multiple time zones induce fatigue as a result of circadian and sleep disturbances.
- An aviation study of 747-200 pilots flying an 8-leg schedule in 12 days with 25-hour layovers between each 9-hour flight revealed decreased performance and increased sleepiness associated with night flying and cumulative fatigue (Rosekind et al., 1995).
- In industry, cumulative fatigue also affects job performance.
- The accident/injury rate in 9-hour shifts remains fairly constant, but the rate progressively increases 3 fold after extended duty of 16 hours (Rosa, 1995).
- Some significant aviation incidents have been partially attributed to fatigue
- Korean Air Flight 801 (controlled descent into terrain on approach)
- China Air Flight 006 (significant and rapid loss of altitude in flight)

## Restrictions on Flight Duration May Not Be Enough

- Federal Aviation Regulations, Subpart R, Section 121.480-121.485 requires:
- the presence of 3 or more pilots and an additional crewmember for flights longer than 12 hours in any given 24-hour period
- the availability of sleeping facilities on board the aircraft used for such flights (the duration of on-board rest is not mandated)
- limiting pilots to no more than 350 hours during 90 consecutive days or 1000 hours during 12 months
- giving pilots, upon returning to home base, a rest period at least twice the number of hours flown since the last rest period at his base
- These provisions have worked fairly well, but aircrew fatigue (and pilot duty time) remains an issue.
- Additional restrictions on pilot duty time may be forthcoming.

## Fatigue Has Not Been Eliminated by the Existing Rules

- Examples of errors reported through the ASRS that were potentially fatigue-related include:
- altitude deviations
- improper fuel calculations
- track deviations
- landings without clearance
- landing on the wrong runway
- Many fatigue-related events may be due to uncontrolled, spontaneous sleep episodes on the flight deck (as reported by members of long-haul crews).

## Technological Advances May Make Matters Worse

- Pilot fatigue may become more critical with the advent of newer, longer-range aircraft:
- Airbus 340-500 and Boeing 777-200X will be capable of flying in excess of 18-20 hours
- This represents a 4-6 hour increase in the duration of the longest flights currently flown.
- This will extend the longest flight-duty day from 14-16 hours upwards to 20+ hours.

## Continuous Wakefulness Alone Affects Pilots Even in Short Flights

**Flight Simulator Performance**

**Psychological Mood**

**Baseline**

**Deprivation Day 1**

**Deprivation Day 2**

**Control Accuracy**

**Time of Day**

**We already know that aviators who remain awake for 20 or more continuous hours show significant decrements in flight performance and marked elevations in mood disturbances *****(and this is when the flights are only 1 hour long)***

**Baseline**

**Deprivation Day 1**

**Deprivation Day 2**

**Time of Day**

**Disturbance Score**

- 22 hours awake

## Long Periods in the Seat Likely Will Compound the Problem

**Controlled-activity periods reduce sleepiness in 6-8 hour flights, but fatigue continues to be noticeable towards the end *****even in pilots who receive frequent breaks*****.  What will be the effects of even longer flights? **

## Will Extending Long-hauls an Extra 4-6 Hours Create New Problems?

- Will currently accepted long-haul fatigue countermeasures be sufficient to avoid problems in longer flights?
- Or will additional crewmembers, modified on-board rest procedures, different types of on-board rest facilities, automated alertness monitoring, or other strategies be needed?
- If on-board rest is the key to maintaining performance, what is the best time for crews to rest?
- Answers to these questions will require systematic research in a controlled aviation environment.

## Proposed Research

- To research this problem, several controlled simulation studies will be conducted to:
- Document the extent of alertness/performance decrements associated with 18-hour flights (with no countermeasures)
- Establish whether the currently-accepted fatigue remedy (rostered on-board crew rest) manages these decrements
- Determine the best times for moderate-duration on-board crew rest (early vs. late in the flight)
- Determine whether a modified on-board rest schedule (shorter rest periods at wider intervals) is more effective than a long break
- If the modified approach (i.e., short naps) appears viable, evaluate the influence of nap timing (early, middle, or late in the flight) on performance maintenance
- Explore the effectiveness of countermeasures other than bunk sleep and napping
- Examine the impact of various individual factors (circadian, sleep need, etc.) on susceptibility to decrements and efficacy of countermeasures

## The Initial Project

- To begin research into these areas, a simulation study will:
- Characterize the alertness/performance decrements associated with 18-hour flights
- Establish the impact of a strategy used currently by a representative airline (rostered on-board crew rest) on these decrements
- Determine the impact of time of rest (early vs. late in the flight) on subsequent alertness and performance
- Determine the impact of a modified rest schedule (shorter rest periods at wider intervals) on subsequent alertness and performance
- To accomplish these objectives, separate groups of aviators will be tested under:
- 18-hour 4-person augmented flights with consolidated bunk sleep
- 18-hour 4-person augmented flights with fragmented bunk sleep
- 18-hour 2-person flights without bunk sleep

## Methods (1)On-board Rest Schedule

- A double augmentation scenario (as implemented operationally) will be used:
- single/double augmentation affects the maximum duration of onboard rest
- In single, maximum rest length = (flight period - 1.5 h) / 3
- In double, maximum rest length= (flight period - 1.5 h) / 2
- In this study, crew augmentation will be:
- Single consolidated rest period either early in the flight or late in the flight
- Two shorter rest periods at wider intervals
- A total of 7 hours of bunk sleep will be permitted in two groups
- One group will be given a single consolidated sleep opportunity either at 0015-0715 or at 1015-1715
- One group will be given 2 shorter sleep opportunities either at 0015-0345 and 1015-1345 or 0345-0715 and 1345-1715
- One group will be given no sleep opportunities

## Methods (2)Research Participants

- A total of 30 aviators will be recruited:
- Participants will have experience with long-haul flights
- They will possess current Class I physicals
- They will be current and qualified in the B747
- To the extent possible, they will be recruited from the same airline
- Participants will be divided into 3 groups:
- Three 4-person augmented flights with consolidated bunk sleep
- Three 4-person augmented flights with fragmented bunk sleep
- Three 2-person flights without bunk sleep

## Methods (3)Materials and Apparatus

- Testing will be conducted in the NASA Ames B747-400 simulator.
- Data will be collected on:
- Psychomotor/cognitive vigilance (PVT)
- Psychological mood/alertness (VAS)
- Operational variables
- Physiological alertness (EEG)
- Activity levels (WAMs)
- In the conditions permitting on-board sleep, the following will be measured:
- Sleep onset and duration (determined via polysomnography)
- Sleep quality

## Methods (4)Example Flight/Training/Testing Schedule

- A double-augmented, transpacific, 18-hour night flight scenario from Los Angeles, CA to Perth, Western Australia will be simulated.
- Departure time will be approximately 2315 PST and arrival time will be approximately 1915 PST.
- Crewmembers will simulate a day of commuting into LAX prior to the flight by reporting to Ames at 0900.
- Four days prior to arrival, subjects will begin wearing wrist-activity-monitors (WAMs).
- Upon arrival, physiological sensors will be attached.
- Pre-flight training will be conducted every 2 hours from 1100 to 2100.
- In-flight testing will occur every waking hour from 15 minutes prior to departure to 45 minutes after arrival in all 3 groups.

## Methods (5) Schematic of In-Flight Schedule

- Methods (5) Schematic of In-Flight Schedule

**Consolidated rest**

**Fragmented rest**

**2300**

**0700**

**1500**

**1900**

**15-minute test sessions will be conducted hourly during wakefulness**

**0300**

**1100**

**No rest**

**7 h Bunk Rest**

**7 h Bunk Rest**

**3.5 h Rest**

**3.5 h Rest**

**3.5 h Rest**

**3.5 h Rest**

## Data Analysis (1)

- The pattern of alertness/performance decrements in the no-rest condition throughout the entire 18-hour flight will be examined
- Changes across all testing times in the no-rest group will be assessed on
**PVT reaction times and lapses**
**VAS sleepiness/fatigue ratings**
**Operational variables**
**EEG power spectral data (delta, theta, alpha, and beta activity)**

## Data Analysis (1) Schematic

- Data Analysis (1) Schematic

**Consolidated rest**

**Fragmented rest**

**2300**

**0700**

**1500**

**1900**

**All sessions throughout the no-rest condition will be compared**

**0300**

**1100**

**No rest**

**7 h Bunk Rest**

**7 h Bunk Rest**

**3.5 h Rest**

**3.5 h Rest**

**3.5 h Rest**

**3.5 h Rest**

## Data Analysis (2)

**The overall influence of testing conditions (groups) will be examined**
- Test sessions common to all groups will be compared (first, middle, and end of flight)
- PVT, VAS, operational variables, and EEG data will be examined at these times

## Data Analysis (2) Schematic

- Data Analysis (2) Schematic

**Consolidated rest**

**Fragmented rest**

**2300**

**0700**

**1500**

**1900**

**Common waking sessions across all groups will be compared**

**0300**

**1100**

**No rest**

**7 h Bunk Rest**

**7 h Bunk Rest**

**3.5 h Rest**

**3.5 h Rest**

**3.5 h Rest**

**3.5 h Rest**

## Data Analysis (3)

**The pattern of decrements between each rest condition and the no-rest condition will be assessed**
- The waking sessions in the consolidated-rest groups will be compared to the corresponding sessions in the no-rest group
- The waking sessions in the fragmented-rest groups will be compared to the corresponding sessions in the no-rest group
- PVT, VAS, operational variables, and EEG data will be examined

## Data Analysis (3a) Schematic (Early Consolidated)

- Data Analysis (3a) Schematic (Early Consolidated)

**Consolidated rest**

**Fragmented rest**

**2300**

**0700**

**1500**

**1900**

**All common waking sessions (early-consolidated-rest versus no-rest) will be compared**

**0300**

**1100**

**No rest**

**7 h Bunk Rest**

**7 h Bunk Rest**

**3.5 h Rest**

**3.5 h Rest**

**3.5 h Rest**

**3.5 h Rest**

## Data Analysis (3b) Schematic (Late Consolidated)

- Data Analysis (3b) Schematic (Late Consolidated)

**Consolidated rest**

**Fragmented rest**

**2300**

**0700**

**1500**

**1900**

**All common waking sessions *****(late-consolidated-rest versus no-rest)***** will be compared**

**0300**

**1100**

**No rest**

**7 h Bunk Rest**

**7 h Bunk Rest**

**3.5 h Rest**

**3.5 h Rest**

**3.5 h Rest**

**3.5 h Rest**

## Data Analysis (3c) Schematic (First-Cycle Fragmented)

- Data Analysis (3c) Schematic (First-Cycle Fragmented)

**Consolidated rest**

**Fragmented rest**

**2300**

**0700**

**1500**

**1900**

**All common waking sessions *****(1st-cycle-fragmented versus no-rest)***** will be compared**

**0300**

**1100**

**No rest**

**7 h Bunk Rest**

**7 h Bunk Rest**

**3.5 h Rest**

**3.5 h Rest**

**3.5 h Rest**

**3.5 h Rest**

## Data Analysis (3d) Schematic (Second-cycle fragmented)

- Data Analysis (3d) Schematic (Second-cycle fragmented)

**Consolidated rest**

**Fragmented rest**

**2300**

**0700**

**1500**

**1900**

**All common waking sessions *****(2nd-cycle-fragmented versus no-rest)***** will be compared**

**0300**

**1100**

**No rest**

**7 h Bunk Rest**

**7 h Bunk Rest**

**3.5 h Rest**

**3.5 h Rest**

**3.5 h Rest**

**3.5 h Rest**

## Data Analysis (4)

- The waking sessions in the consolidated-rest group will be compared to the corresponding sessions in the fragmented-rest group

## Data Analysis (4a) Schematic

- Data Analysis (4a) Schematic

**Consolidated rest**

**Fragmented rest**

**2300**

**0700**

**1500**

**1900**

**Waking sessions from the beginning, middle, and end of the flight will be compared**

**0300**

**1100**

**No rest**

**7 h Bunk Rest**

**7 h Bunk Rest**

**3.5 h Rest**

**3.5 h Rest**

**3.5 h Rest**

**3.5 h Rest**

## Data Analysis (4b) Schematic

- Data Analysis (4b) Schematic

**Consolidated rest**

**Fragmented rest**

**2300**

**0700**

**1500**

**1900**

**Waking sessions from the beginning, middle, and end of the flight will be compared**

**0300**

**1100**

**No rest**

**7 h Bunk Rest**

**7 h Bunk Rest**

**3.5 h Rest**

**3.5 h Rest**

**3.5 h Rest**

**3.5 h Rest**

## Data Analysis (5)

- Average performance across all groups (regardless of testing time) will be compared
- Averaged PVT, VAS, Operational performance, and EEG data from an equivalent number of sessions will be examined

## Data Analysis (6)Amount and Quality of Sleep

- The amount and quality of sleep in both the consolidated and fragmented rest periods will be evaluated
- EEG, EMG, and EOG data will be examined using standard criteria
- An estimate of sleep quality/duration both pre-study and post-study will be determined via WAM data

## Estimated CostsInitial Study

- Simulator time 					250K
- Research assistants (4 full-time for 1 year) 	200K
- Principal investigator (full-time for 1 year) 	105K
- Testing materials/equipment 			110K
- Participants (travel, per diem, pay, etc.)	  55K
- Other (briefings, coordination mtgs, etc.)	  18K
- 						TOTAL	738K

## Proposed Follow-On Research

- Following this initial study, subsequent investigations will be conducted to:
- Explore the impact of different flight schedules (morning vs. evening departures) on in-flight sleep and performance
- Evaluate the effects of single vs. double augmentation on the efficacy of on-board sleep
- Explore the effectiveness of countermeasures other than bunk sleep and napping
- Examine the impact of various individual factors (circadian, sleep need, etc.) on susceptibility to decrements and efficacy of countermeasures