ASRS Directline

 Issue Number 5 : March 1993

One More Leg, The Commuter Pilot's Conumdrum

by Robert Matchette

"I had an 11.6 hour duty day with 8 legs. That night I had a reduced rest scheduled to exactly 8 hours. On the second day we were scheduled for 6.3 hours of duty with 5 legs. Both my F/O and myself awoke the next morning still feeling very fatigued and sleepy. On the last leg of the day, my F/O was flying as we were descending into the airport area for the approach. I fell asleep for about one minute and woke up so disoriented that for 500 feet I watched the altimeter unwind and wondered why we were climbing. This is not the first such incident. I have had altitude busts, missed checklist items, etc., following reduced rests." (ACN 203509)

ASRS receives many reports from pilots of commuter aircraft alleging that fatigue induced by long duty schedules, compounded by inadequate rest, is often a primary factor in aviation safety incidents.[Endnote 1]

Major Carrier or Commuter?

Major air carriers and commuter operators tend to serve different segments of the air transport market. Major carriers usually operate larger aircraft over greater distances, while commuter carriers operate smaller aircraft over short, regional route structures with greater frequency of service. Each are governed by different provisions of the Federal Aviation Regulations (FARs). Part 121 of the FARs applies to aircraft of more than 30 seats operated in scheduled commercial air service, while in this review we examine FAR Part 135 as it applies to aircraft of 30 seats or less operated in scheduled commercial air service with two pilots.

Duty Time Requirements

Many of the rules and flight duty requirements differ between major air carriers (Part 121) and commuters (Part 135). Table 1 summarizes differences in the duty time requirements of these respective carriers.

Table 1--FAR Major and Commuter Carrier Flight Time Limitations

Time Period FAR 121 Max FAR 135 Max The 135 Difference
1 Calendar Year 1,000 flight hours 1,200 flight hours 200 hours per year
1 Calendar Month 100 flight hours 120 flight hours 20 hours per month
7 Consecutive Days 30 flight hours 34 flight hours 4 hours in 7 days


Dr. R. Curtis Graeber [Endnote 2] summarized his findings on fatigue in air transport operations in the Proceedings of the Flight Safety Foundation 38th International Air Safety Seminar in 1985 as follows:

"An initial analysis of NASA's Aviation Safety Reporting System (ASRS) in 1980 revealed that 3.8 percent (77) of the 2006 air transport crew member error reports received since 1976 were directly associated with fatigue (Lyman and Orlady, 1980). This may seem like a rather small proportion, but as the authors emphasize, fatigue is frequently a personal experience. Thus, while one crew member may attribute an error to fatigue, another may attribute it to a more directly perceived cause such as inattention or a miscommunication. When all reports which mentioned factors directly or indirectly related to fatigue are included, the percentage increases to 21.1 percent (426). These incidents tended to occur more often between 00:00 and 06:00 [local time] and during the descent, approach or landing phases of flight. Furthermore, a large majority of the reports could be classified as substantive, potentially unsafe errors and not just minor events."

The Situation for Commuters

Why should there be any difference in the rules for major carriers and commuters? When Part 135 regulations were drafted, the equipment used in commuter operations was relatively slow and unsophisticated. Some of the equipment used in commuter operations is becoming more advanced, with commuters utilizing Electronic Flight Instrument Systems (EFIS), Traffic Alert and Collision Avoidance System (TCAS II) and autoflight equipment previously installed on larger turbojets. However, much of the equipment used by these commuter carriers is older-style technology, having primary navigation and instrumentation as compared to more advanced air carrier counterparts, and this often translates to a higher workload. In addition, aircraft having 19 or fewer passenger seats do not require flight attendants, further increasing the duties and workload of the crews operating them.

Commuter flight crews, unlike their Part 121 counterparts, often spend more of their flight time operating below 10,000 feet in busy terminal environments where there can be many changes to speed, altitude and heading assignments, such as New York, Los Angeles, San Francisco, Atlanta, Chicago, and Washington/Baltimore. To make matters more difficult, commuter aircraft may spend a greater percentage of flight time in instrument meteorological conditions (IMC) than turbojet equipment due to their lower cruising altitudes. These factors certainly aggravate the effects of acute and chronic fatigue. Consider the following pilot report:

A Sample Schedule

Below is a de-identified copy of an actual daily series of scheduled flights flown by a commuter carrier. To preserve anonymity, flight numbers and destinations have been removed (see Note 1). This trip was constructed in accordance with FAR 135.265. In this example, note that CITY B is one of the busy terminal environments discussed above, and the crew flies into AND out of this hub five times. (See Note 2.)

The crew flying this trip was to report for duty one hour prior to the first departure, and would remain on duty for fifteen minutes after arrival at CITY D at the completion of the last leg. It is important to note that delays during the day may become cumulative, so that completion of the trip may be much later than scheduled. The following graphic (Figure 1) summarizes the day's activities.

Figure 1 A Sample Commuter Carrier Schedule

Note 1: This schedule was reproduced from a House Sub-Committee hearing on Government Affiars in Washington, D.C., April 1, 1992, chaired by then representative Barbara Boxer.
Note 2: Times shown in the top bar are scheduled departure and arrival times, while times appearing below "City" and the right arrow in the bottom bar are scheduled ground and flight times, respectively.

If this trip is flown as scheduled, 8 hours and 45 minutes is available for: 1) traveling to and from lodging, 2) eating evening and morning meals, and, 3) preparing for and arising from sleep. If transportation to and from lodging takes 30 minutes, and evening and morning meals can be consumed in one hour, and one hour is devoted to preparing for and arising from sleep, then only 6 hours and 15 minutes remain for sleep (assuming one can immediately drop off to sleep). Any delays in ground transportation or eating of meals will of course reduce the time available for sleep.

Changing Schedules

Unlike most 9-to-5 jobs, commuter airline schedules can change monthly, and within a given month, report for duty and off-duty times change as well. Such changes can reduce the amount of useful rest regardless of the length of layover, as this reporter notes:


The rest time between scheduled duty segments is of paramount concern to many commuter pilots. Writes one tired Captain:

Standup Overnights

Another scheduling procedure used at regional carriers is known as the continuous duty or "stand-up" overnight. These schedules typically begin in the late evening hours and involve a one or two-leg flight from a hub city to an outlying destination where the crew remains on duty continuously throughout the night until returning to the hub city, sometimes at first light. While the crew is often supplied lodging, there is little time for sleep. As many as three of these stand-up overnights may be scheduled in consecutive days resulting in what some reporters describe as chronic fatigue. One reporter notes:

The Captain of the same flight adds:

Another reporter describing an incident while on a continuous duty overnight claims:

A reporter admitting to falling asleep at the controls, adds:

Quick Review

Let's review the problems many commuter pilot reported to the ASRS:

  1. Commuter flight crews may experience greater workload because their aircraft are often less sophisticated than their Part 121 counterparts.

  2. Flight schedules may have many legs, with pilots often returning again and again to high-density, high-workload airports.

  3. Due to shorter trip segments and aircraft of lower performance, commuter flights are often required to operate IN the weather, not above it.

  4. Commuter pilots often encounter duty schedules with minimum rest between duty periods.

  5. Standup overnights and oft-changed schedules can lead to chronic fatigue due to sleep disruption and deprivation.

In spite of these operating conditions, commuter (FAR Part 135) flight crews have less restrictive duty schedule regulations than pilots for major air carriers. One reporter states:

Looking for Solutions

One possible solution to the potential problems associated with fatigue in the commuter carriers could be to simply "cut and paste" the duty and rest requirements of part 121 into Part 135. Indeed, one senior FAA official has been quoted in Aviation Week & Space Technology [Endnote 3] as predicting "...a leveling, and it would be in an upward direction..." to improve duty schedule standards for FAR Part 135 carriers and pilots.


Notwithstanding possible changes to FAR Part 135 duty regulations, there are a few suggestions that can help reduce the impact of stress and fatigue-related problems faced by commuter pilots faced with demanding flight and duty schedules. In fact, these recommendations are good ones for all pilots.

Planning: For most of us, encountering the unexpected translates to increased stress, and increased stress results in increased fatigue. Many veteran pilots "mentally fly" their flights before showing up for duty, attempting to identify potential problems and possible solutions -- this can help reduce the stress of the unexpected.

CRM: Effective sharing of cockpit workload can also reduce stress and fatigue. Flight crews should review Crew Resource Management techniques before flight, and critique their performance afterwards to identify those areas where change or improvement is possible.

Rest: Getting adequate rest is difficult if a duty schedule calls for periods of reduced rest or stand-up overnights. It is recommended that pilots limit their activities and get adequate rest before reporting for difficult duty schedules. This can help reduce the impact of chronic (accumulated) fatigue.

Physical Fitness: Being physically fit will also reduce the impact of arduous duty schedules. It is recognized that moderate exercise reduces the effect of stress; taking a brisk walk (or some other form of exercise) after a long day, or between flight segments if time permits, means feeling better and sleeping better.

Nourishment: The benefits of proper and regular diet are well known, but many reporters to the ASRS note the difficulty in obtaining adequate nourishment during extended duty periods or following late arrivals. (Adequate nourishment doesn't mean a hamburger and coffee, either.) Millions of workers take lunch to work, so pilots with schedules that may preclude a good restaurant meal should do the same. Take a sandwich, and pack fruit and vegetables.

1. This is not to say that flight crews of large transport aircraft in major air carrier operations do not also face the fatigue and other related problems of difficult flight and duty schedules--they can and do. (See Last Leg Syndrome, by Capt. William Monan, ASRS Directline Issue #2.)
2. Dr. Graeber, now with the Boeing Company, is a former research scientist with the NASA-Ames Research Center.
3. Washington Outlook, Aviation Week and Space Technology, 23-Aug-93, page 21.

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