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Human Factors Considerations for the Design and Evaluation of Electronic Flight Bags

Divya C. Chandra, U.S. DOT Volpe Center, Cambridge, Massachusetts
Susan J. Mangold, Battelle Memorial Institute, Columbus, Ohio

Return to Volpe EFB Publications and Projects


There is currently great interest in developing stand-alone electronic devices to support flight deck tasks. These devices, called "Electronic Flight Bags" (EFBs), were originally seen as a repository for electronic documents. Today, some airlines envision EFBs as multi-function devices supporting an array of applications, while others envision a simple low-end device used only for viewing documents, or perhaps for performing flight performance calculations.

The Federal Aviation Administration (FAA) is charged with approval of EFBs for installation and use in aircraft. The approval process will be a multi-dimensional effort requiring an understanding of how the device functions and is used by crews, how the device interacts with other cockpit equipment, and training and operating procedures. Volpe Center has been tasked with writing a document on the human factors issues related to EFBs.

Our goal is for the document to be of value to both system evaluators in the FAA and system designers in industry. Our challenge was to create a document that addresses the wide range of proposed EFB implementations, suits the needs of the various readers, and provides useful information for designers and evaluators. In this paper we review the design of the document and how it addresses each of these requirements. We also give an overview of the content of the document and provide illustrative extracts from the text.


In a world where small portable computers are increasingly common for personal and business use, it is not surprising to find that aircraft operators would also like to have small, portable electronic information-management devices to help pilots conduct flight operations more efficiently and safely. The original concept for this device was as a repository for electronic documents. That is, it would be an "Electronic Flight Bag" storing electronic copies of documents, such as operating manuals and checklists, that are usually required in hard copy during a flight.

As the concept of an EFB was explored it became clear that the device’s potential was much greater than first envisioned [1, 2]. As evidenced by the development of the Integrated Crew Information System (ICIS) by Avionitek, Inc., an EFB could support a wide array of functions beyond that of an electronic library. For example, ICIS supports sophisticated electronic checklists, computation of flight performance variables, and in the near future, real-time displays of weather.

Even though the operational concept of an EFB is relatively immature there is significant interest in developing EFBs from airlines and avionics manufacturers. Industry groups have asked the Federal Aviation Administration (FAA) to develop a plan for operational approval of EFBs. This plan will be distributed in a public document, an Advisory Circular, to be released for public comment in October 2000 [3].

Because EFBs could strongly affect how the pilot performs his/her job, their impact must be carefully evaluated from a human factors perspective. Volpe Center was tasked with assisting the FAA in developing advisory materials for the human factors evaluation of EFBs. Our product is a document in which evaluation topics are identified, and requirements and recommendations for EFBs are specified. Our goal is for the document to be of value to both system evaluators in the FAA and system designers in industry.

In this paper, we begin by exploring the EFB concept in more detail. Next, we present a more specific statement of our project challenges. The bulk of this paper addresses the EFB human factors guidance document in more detail. We discuss the document scope, content, and format, all in the context of how the document was crafted to meet its goals. Two illustrative extracts from the document are also included.

Background—What Is an EFB?

Earlier, we mentioned that the operational concept for an EFB is still immature. While this is true, there are some core characteristics of an EFB that define the basic concept. An EFB is an electronic information management device for use by pilots in performing flight management tasks. It typically consists of a screen and controls in a self-contained unit that is relatively small, weighing only a few pounds at most. EFBs can store and display large amounts of data. Some existing EFBs run proprietary operating systems, but most are compatible with the Microsoft Windows® operating system. For example, the Northstar Technologies CT-1000 (see Figure 1) runs Windows 98®. The Northstar hardware is custom-built for aircraft use, but some manufacturers host EFB software on more standard laptop computers.

Beyond these characteristics, EFB concepts begin to vary significantly. Some are relatively simple units in that they support only one or perhaps two functions (e.g., electronic documents and flight calculations). Other EFBs support a wide array of functions that the pilot can select from at any time. Of course, it may be easy to upgrade EFBs by installing new software applications, just like any other computer, so a single-purpose EFB could evolve into a multi-function unit.

Some EFBs may be mounted within the aircraft cockpit, and even draw power from the aircraft. Other EFBs will be hand-held, operating on batteries. More sophisticated EFBs could communicate with cockpit systems and/or each other. For example, ICIS units communicate with one another via infra-red signals. (This is useful when, for example, the co-pilot completes an electronic checklist item; that information is immediately displayed on the captain’s ICIS unit.) EFBs could also display real-time weather and/or traffic information obtained via data link.

While the initial customers for EFBs are primarily airlines, the EFB is also expected to penetrate the corporate and general aviation markets. Each market has a slightly different operational concept for the EFB. Even among various airlines, there are multiple concepts for use of an EFB. Some airlines want the low-end devices that support one or two functions. Others want high-end EFBs that either provide new information services (e.g., real-time pilot messaging) or support functions that are traditionally implemented on standard cockpit avionics (e.g., the Enhanced Ground Proximity Warning System).

Some airlines would also like the EFB to be integrated into their training programs, so that pilots could take the devices home and complete part of their training off-site. For example, pilots could review operating manuals on a stand-alone portable device at any location.

Finally, it is conceivable that some EFBs could eventually be certified as the sole source of some types of flight-critical information. For example, the electronic checklists on an EFB could replace (not just supplement) paper checklists.

Project Challenges

Volpe Center was tasked with assisting the FAA in developing advisory materials for the human factors evaluation of EFBs. We faced three main challenges. First, the guidance has to address the wide range of proposed EFB functionality, discussed above. To accomplish this, we needed to be aware of the many EFB concepts proposed by industry. We also had to be aware of airline requests for EFB functionality. We met this challenge through our participation in the Air Transport Association's Digital Data Working Group (ATA DDWG). The group consists of airlines and manufacturers, many of whom are pursuing the EFB concept. This group also provides valuable feedback on our draft guidance document.

Our second challenge was to package the guidance in a format that was useful for the audience. Our audience includes (a) members of the FAA who are involved in the approval of EFBs, including field inspectors, Aircraft Certification, and Flight Standards, (b) industry designers of EFBs and (c) EFB customers. Our readers within the FAA will approach the document with different interests in mind because the approval process will be a multi-dimensional effort. The approval process will require an evaluation of how the device functions and is used by crews (i.e., "equipment issues"), how the device interacts with other cockpit equipment (i.e., "installation issues"), and training and operating procedures. FAA field inspectors will be interested in very practical, operational issues. Manufacturers of different EFBs will also approach the document from their own points of view; they will want to see the guidance related to only the functions performed by their EFB. Therefore it was important to organize the document by both EFB function and approval aspect.

Our final, and on-going, challenge is to provide information that is useful to both system designers and system evaluators. Each piece of guidance in the document must be relevant, specific, and to the point. If the guidance is well written, the jobs of both the system designers and evaluators will proceed more smoothly. In the next section, we go into more detail about how the guidance document is organized and written to meet this challenge.

Document Overview

In this section, we discuss the scope of the EFB human factors document, its content, and structure. At the end of the section, two extracts from the document are presented. The extracts illustrate the structure and type of guidance provided in the full document.


Creating guidance for all possible EFB functions is a long-term effort. We chose to split up the task into yearly efforts. Our first year’s effort will be distributed as "Version 1" of the document. This allows us to distribute guidance on an initial, basic level of EFB functionality as soon as possible. The document is modular, so adding information on newer or more complex EFB functions will be straightforward.

Version 1 of the EFB human factors document contains both general human factors considerations and specific considerations for an initial set of functions that includes electronic documentation, electronic checklists, and flight performance calculations. These functions were chosen because they are the most mature applications to date. Several airlines are in the process of converting manuals into electronic form, the first step towards placing the documents on a portable flight deck device. Electronic checklists are already available on some newer aircraft models. The algorithms for computing flight performance are well understood, and have been implemented for use on standard personal computers. These functions have even been implemented in industry prototypes of multi-function EFBs.

Version 2 of the EFB human factors document, to be completed in 2001, will address more complex functions, such as electronic charts, and functions that involve display of real-time data, such as weather or traffic information.


We cover four key types of human factors issues in the guidance document:

  • Usability of hardware
  • Usability of software user interface
  • Integration of hardware and software with existing cockpit systems
  • Design of training/procedures for EFBs

Note that there is no single "best design" solution for these issues. We are not telling manufacturers what design choices to make. We are providing them with information on the human factors issues that arise given different EFB design choices.


The structure of the document has evolved to meet the needs of the various readers. The final structure is a combination of techniques and suggestions that we culled from other guidance documents [4–6] and feedback from our FAA and industry reviewers.

There are four main content sections in the document. The first section covers general topics, under the title of System Considerations. Each of the other sections pertains to a particular EFB function: electronic documentation, electronic checklists, or flight performance calculations.

Within each main content section, guidance is organized into one-page "considerations." (An example of a complete one-page consideration is given in the next section.) The title of the consideration states the function or general issue that is being addressed; if a particular EFB does not support that function or that issue is not relevant, then that guidance statement does not apply. So, the title of the consideration helps the reader determine whether that information applies to a given product.

Each consideration contains one or more summary guidance statements at the top of the page, followed by detail information in three subsections:

  • Problem Statement
  • Example(s)
  • Evaluation Questions

In the Problem Statement, we clearly identify why the topic is important, and what risks are taken if the problem is not addressed. Below that, we give examples of the problem and possible solutions. In the Evaluation Questions, we give guidance on what a field inspector should look for during the evaluation. These questions are open-ended. They prompt the evaluator for areas to examine instead of giving him/her a formal set of criteria that must be met by the EFB to pass some minimum approval standard. The open-ended questions allow inspectors to use their own judgment in each specific situation.

Each formal guidance statement is labeled. The label reflects the FAA approval aspect and the level of guidance. Labeling guidance statements helps different readers, especially those from the FAA, find topics of interest quickly.

There are three types of FAA approval aspects.

  • Equipment
  • Installation
  • Training/Procedures

These approval aspects were discussed earlier, in the section on Project Challenges. The first aspect, Equipment, is concerned with how the EFB is used in and of itself. These are issues that can be tested in a laboratory setting. Most software design issues will be Equipment issues. The second approval aspect, Installation, concerns EFB evaluations that must be performed in the context of a cockpit. For example, when the EFB is mounted in a structural cradle, it should not obstruct access to other critical flight controls and displays. Some considerations contain more than one guidance statement that address multiple approval aspects. For example, in the sample consideration on stowage requirements (see Figure 2) there are two guidance statements, one related to installation and the other related to training/procedures.

Our guidance statements are classified as Requirements, Recommendations, Good Practices, or Issues. These categories reflect the fact that we do not always know in advance what the "right" design is. The guidance statements should identify unacceptable design solutions without requiring that manufacturers implement the "best" designs. For installation and equipment issues, the different levels of guidance leave room for innovation in the design of EFBs. For training/procedures issues, the different levels of guidance allow room for different operators to develop training/procedures that are consistent within their company.

The guidance statements are written to (a) allow flexibility (rather than requiring design solutions) (b) be specific to EFB functions, which the EFB may or may not support, and (c) be specific to operational environments such as the type of operations (e.g., general aviation versus airline) and phase of flight.

Sample Considerations

Two extracts from the EFB human factors document are presented below in Figures 2 and 3. Figure 2 shows an excerpt on the stowage area for portable units. Each guidance statement is labeled by the FAA approval aspect and the level of guidance. Also, notice how the installation requirement is written to apply to a specific situation. Exceptions are noted. The exception regarding EFBs that are not used for flight critical information is designed to allow less expensive implementations for general aviation users who may want less capable units. The problem statement below is short and to the point, as are the examples. Notice also how the Evaluation Questions are open-ended, leaving some room for adjustment to individual situations.

Stowage Area for Portable Units

Installation Requirement(s)

A stowage area with a securing mechanism for the EFB is required for storage of portable units when they are not in use.

Note: If the EFB is designed to be held in a structural cradle, the cradle may satisfy the requirement for a stowage area.

Note: For EFBs that are not used as the only means of performing any flight critical tasks, this requirement may be downgraded to a strong recommendation.

Read the full report (PDF): Human Factors Considerations in the Design and Evaluation of Electronic Flight Bags (EFBs) Version 2.

 Northstar Technologies CT-1000 EFB software running on Windows 98.
Figure 1: The Northstar CT-1000 weighs 3.25 lbs. and has a 6.4" diagonal color display. (Photo courtesy of Northstar Technologies)