# Presentation: 033967

## Enabling Strategic Flight Deck Route Re-Planning Within A Modified ATC Environment: The Display of 4/D Intent Information on a CSD 

- Vernol Battiste & Walter W. Johnson
*NASA Ames Research Center*
- Sheila Holland Bochow
*San Jose State University*

## Outline

- Air ground concept
- Airspace
- Roles and responsibilities
- CDTI design goals
- Full mission simulation
- Objectives
- Procedures
- ATC displays
- Results
- Conclusions

## An Air-Ground Strategic Self-Separation Concept

- Free flight airspace in which current intent is shared between ATC and all aircraft
- 3-D flight plans including waypoints for
- start & top of climb
- top & bottom of descent
- changes to speed (*Not included in Present Study)*
- State information (position, velocity, etc.)** **

## An Air-Ground Strategic Self-Separation Concept (cont.)

- Roles and responsibilities
- The flight deck may identify and resolve strategic conflicts by submitting flight plan changes to ATC for approval (via data link), approved changes  are broadcast
- Under nominal conditions ATC allows flight deck to handle strategic self-separation
- The controller has ultimate authority and responsibility for separation assurance** **

## Goals of CDTI Design

- Maintain at-a-glance viewing (low workload)
- Provide 4-D situational awareness
- Provide conflict alerting
- Provide a path replanning tool (conflict probe & graphical front end to FMS)
- Provide means to datalink revised flight plans to ATC for review

## Basic CDTI Cockpit Display

- 3D Flight Plans
- Individual aircraft ID blocks
- Static and dynamic predictors
- Three levels of relative altitude color coding (co-altitude, above, and below)
**Situational awareness information**
- Multistage strategic conflict alerts
- Traffic relevance coding  (i.e. temporal proximity, “free flight” status) using intensity levels and symbol shape (nose)
**Anti-clutter features:**
- Full and partial data blocks (Tail tags)
- Individually controllable data blocks
- Smart Tags
- Global ID and Route Declutter
**Captain/First Officer display sharing**
**Touchpad and panel-mounted controls**

**Basic CDTI Cockpit Display**

## CDTI Flight Path Replanning

- Insert altitude change pair
- Bottom of climb, LAS 140
- Top of climb, LAS 161
- Tests new path for conflicts
**Datalink New Flight Plan to ATC for approval through FMS FANS links**
**New Flight Plan entered into FMS**

**CDTI Flight Path Replanning**

## Controller Approves Flight Plan Change

- ATC receives proposed de-conflicted flight path – graphic overlay on display
- Evaluates proposed routing and traffic
- Approves change

## Simulation Study Objectives

**Simulation Study Objectives**

- To assess the value of 4/D intent information (flight plans) for flight crews performing  strategic self separation  during en route free flight operations.
- To obtain display usage measures for the various display tools.
- To obtain flight crew feedback on utility (effectiveness and workload) of specific display features and overall display design.
- *** To obtain measures of flight crew / ATC coordination
- *** To obtain measures of effectiveness of procedures emphasizing low and high ATC responsibility

## Tools & Procedures

**Tools & Procedures**

- Eight 747-400 flight crews managed separation utilizing CDTI
- Basic Display
- Alerting System
- Advanced Route Analysis Tool
- Flight crew procedures
- Develop resolutions
- Data-link proposed resolutions to ATC
- Implement upon agreement from ATC
- ATC Procedures - full authority and responsibility
- Normal Operations – intervene at any time
- Delay intervention – without adversely impacting sector operations, allow flight crews to self-separate

## Approach

- 10 Boeing 747 flight crew flew 8 en route scenarios
- The flights were conducted in a ATC super sector (FL350 and above) manned by FPL
- The flight crew’s task was to maintain vertical (1000ft) and lateral separation, by re-planning their trajectory and and submitting changes to ATC for approval

## Time in Alert By Intent And Conflict  Type

- Apparent conflicts – alert duration was significantly reduced  with 4-D routes information
- Real conflicts – alert duration was significantly increased with 4-D route information
- With 4-D flight plans crews were not subject to the false alarms that occurred when ballistic (non-flight plan based) alerting logic was used

**Notes:**
During the simulation flight crews were exposed to two types of intent information; shared and unshared flight plan information. In the shared condition flight plan data for all traffic in range was updated once a second and was complete, in the unshared condition only ballistic flight trajectories were available to assess future conflicts. During apparent conflicts alert duration was significantly reduced with 4-D flight plan information. Additionally, during real conflicts, alert duration was significantly increased with 4-D flight plan information. This data suggest that the alerting logic would be much more efficient when complete flight plan information is used. Additionally, crews who had access to 4-D flight plan information were exposed to fewer false alarms, which may translate into improved crew confidence in the onboard CSD system. 

## Crew Use of Static VS Pulse Predictors

- Crews used the pulse predictor significantly more than the static predictor
- Comment: Crews reported a preference for the pulse predictor and suggested that it should be selectable for individual aircraft

**Notes:**
Crews utilized the pulse predictor significantly more often than the static predictor. Utilizing the pulse predictor crews were able to determine if traffic on crossing paths were real conflicts. Thus, when set for long extended time intervals, (for example 10 seconds) flight crews could detect traffic conflicts prior to a CSD traffic alert. Some crews utilized this additional time by making smaller modifications to their flight plan. During the post flight questionnaire and verbal debriefings crews reported a preference for the pulse predictor and suggested that individual aircraft selection should be possible. 

## Maneuvers Selection

- Flight Crews utilized both vertical and horizontal maneuvers during flight path re-planning
- Note: During the simulation the B-747 was normally below its flight economy ceiling.

**Notes:**
Recent research has suggested that when presented with a maneuver choice to resolve a traffic conflict, flight crews prefer horizontal over vertical maneuvers. No maneuver preference was found for flight crews who participated in this study. Flight crews utilized both vertical and horizontal maneuvers during flight path re-planning. The distribution of horizontal and vertical maneuvers was about the same even though the B-747 simulator was normally below its flight economy ceiling.   

## Lateral Maneuver Distances by Route Condition

- Maneuvers made during alerts resulted in significantly smaller route deviations (distance) when crews had  4-D route information
- Maneuvers made during non-alert events resulted in significant reductions in trip length (distance) when crews had  4-D route information

**Notes:**
Flight crews that had access to 4-D flight plan information on traffic made significantly smaller route deviations during flight path re-planning for traffic. Additionally, during non-alert flight path re-planning crews with 4-D flight plan information significantly reduced their trip length. These data suggest a significant operational benefit of the CSD system on the flight deck. When maneuvering for traffic user preferences could be taken into account, and that during non-alert events that other factors which effect trip cost could be taken into account.

## Number of ARAT Events by Routes Conditions

- During both alerts and non-alerts – crews performed significantly fewer ARAT activities when  4-D route information was available

**Notes:**
Crews that had access to 4-D flight plan information performed significantly fewer ARAT activities, during both alert and non-alert time periods. This finding suggest that crew workload would be lower with access to 4-D flight plan information. As suggested previously, complete flight plan information could also increase crew confidence in the system.

## Results - Questionnaire

- Post simulation, crews responded to a Likert scale format (1-7 scale) - generally 1 negative, and 7 positive, or preferences with either choice anchoring the scale (e.g.,1- static and 7 - pulse predictors)
- A neutral position of 4 was used as an anchor to evaluate ratings that were significantly (p<0.05) above or below the anchor, on a two tailed t-test.

## Results: Display Clutter with and Without ARAT

**Neutral** responses for clutter with both ARAT -M=4.13, and without ARAT -M=4.5
- Flight crews reported that # of aircraft were the main cause of display clutter
- They suggested that the ability to remove aircraft that were flying away at a different altitude (assumed no longer a threat) could help solve this problem

## Results: Text Size and Readability

**Positive** response
- Tail tags, M=5.69
- Aircraft ID blocks, M=6.0
- Flight plan waypoint names, M=5.78
**Neutral** response
- ARAT waypoint names, M=4.44

**Notes:**
Dimming of waypoint names was a problem when discussing the change with ATC
Waypoint names overlapped with standard waypoint names

## Results: Aircraft Symbols

- Ownship and traffic (size, shape, altitude format, 1 minute predictor, & brightness), **positive** M=5.97
- Color coding of relative  altitudes (blue -above, green - below, and white -same altitude), **Positive** M=6.37
- Comment:
- The color coding allowed an instant recognition of the traffic situation.
- Brightness levels were not as effective.

## Results: Flight Plans

**Positive** response to flight plans (symbol size, shape, waypoints, & altitude segment), M=5.75
**Positive** response to the use of color in the flight plan, M=5.84
**Comment: Broken (dotted ) line was very effective** **for showing altitude change segments**

## Results: Input Controls

- Predictor  panel mounted controls
- Ease of use, **positive**, M=5.61
- Desirability, **positive**, M=5.47
- ARAT panel mounted controls
- Ease of use, **neutral**, M=4.94
- Desirability, **neutral**, M=5.33
- Touch Pad predictor and ARAT
- Ease of use, **neutral**, M=4.69, & M=4.5
- Desirability, **neutral**, M=4.47, & M=4.18

**Notes:**
Precision on the touch pad was lower than  for the control panel

## Results: Aircraft ID Blocks

- 15 of 16 flight crew members reported that information in the flight ID block was necessary
- Comment: One addition to the current information set was suggested - final altitude for climbing and descending aircraft

## Results: Predictors

- Static, **neutral** M=4.44
- Pulse, **very positive** M=6.66
- Preference (1-static or 7-pulse), **positive** M=6.03
- Input devices - controlling predictors
- Control panel, **positive** M=5.56
- Touch Pad, **neutral** M=4.22
- Preference (1 - control panel to 7 - touch pad), M=3.28

## Result: Alerts

- Alert Symbology
- Overall (shape, sound and function), **positive** M=5.63
- Effectiveness when ARAT engaged, **positive** M=5.82
- ARAT symbology (size, shape, waypoints, altitude segment, and waypoint table), **positive** M=5.50
- Alert Resolution
- Preference for vertical or lateral maneuver, **neutral** M=4.47
- Location of initial maneuver (1 - near or 7 - away from ownship), **neutral** M=4.38
- Value of flight plan, **positive** M=5.47
- Alert timing
- Minimum desired time before loss of separation for alert level 3, M=5.63
- Minimum amount of time needed to design, submit, approve and load flight plan changes, M=2.43 minutes ahead of ownship (current design is 1.50)

**Notes:**
All crews wanted to have flight plans for other traffic on the display

## Conclusions

- Flight crew efficiency and workload was reduced with 4-D flight plan information
- Smaller deviations for traffic
- Reduced trip length associated with non traffic related maneuvers
- Fewer ARAT events (less workload)
- Crew responses to 3-D and 4-D traffic information, display clutter, and flight re-planning tools.
- Positive response to 3-D flight plans
- Positive response to pulse predictor
- Positive response to altitude color coding (both flight plan & traffic)
- Neutral response to clutter management tools
- Ratings showed that crews had difficulty with the ARAT controls.
- Neutral ratings for both input devices, panel and touch pad