# Presentation: 497829

## A Simulation Evaluation of a Human Centered Approach to Flight Deck Procedures and Automation for En Route Free Maneuvering

- Walter W. Johnson and Vernol Battiste
- NASA Ames Research Center
- Stacey Granada, Quang Dao, and Nancy Johnson
- San Jose State University

## Outline of Presentation

- En Route Free Maneuvering Concept
- Approach
- Goals
- Simulation Environment
- Method
- Experimental Design and Task
- AFR Flight Rules
- Ames Pilot Participants
- Ames Flight Deck Results
- Separation Management
- Meter Fix Conformance
- Workload & Subjective Opinion
- Conclusions

## En Route Free Maneuvering Concept

- The En Route Free Maneuvering concept was designed to extend present airspace capacity by adding ‘extra’ “autonomous” aircraft into the present en route airspace.  Autonomous aircraft would
- Fly according to Autonomous Flight Rules (AFR)
- Have tools allowing them to maintain separation from AFR and traditionally managed IFR aircraft.
- Manage to meter fix constraints in the presence of traditionally managed IFR aircraft
- Have access to adequate surveillance information on the location and intent of all surrounding aircraft

## Approach

- In June 2004, research teams at the NASA Ames and NASA Langley Research Centers conducted a joint human-in-the-loop test of the feasibility of the* *En Route Free Maneuvering concept. The test
- Simulated flight decks at both centers and simulated ATC at Ames.
- Was flow in a modified portion of the airspace in and around ZFW and Dallas/Fort Worth TRACON.

**This presentation only deals with the results from the flight decks simulated at NASA Ames Research Center**

## Goals of The En Route Free Maneuvering Study

- Evaluate whether autonomous operations in a _*mixed*_ en route and transition airspace are _*feasible*_ and _*scalable*_
**Mixed** – Traditional managed aircraft and equipped  autonomous aircraft share the same airspace
***Feasible**** – Accommodates basic procedural, workload, and safety considerations*
***Scalable**** – The number of en route aircraft can be significantly increased beyond present day  limits*

## Ames Simulation Environment

**AFR Multi-aircraft Pseudopilot Stations**

## 3D Cockpit Situational Display
Ownship and traffic
State and 4D intent information
Fast-time predictors
Manipulable 3D views.
Strategic conflict detection and alerting
Automated conflict burdening symbology
FMS integrated 
Flight path re-planning tool w/ alerting
RTA management tool

- Ownship and traffic
- State and 4D intent information
- Fast-time predictors
- Manipulable 3D views.
- Strategic conflict detection and alerting
- Automated conflict burdening symbology
- FMS integrated
- Flight path re-planning tool w/ alerting
- RTA management tool

**MACS Aircraft Simulator**
- 757-like aircraft model
- 777-like interface
- FMS
- MCP with integrated alerting
- Primary flight display

**Ames AFR Aircraft Equipage**

**ADS-B**:
- AFR & IFR: Broadcast state and intent (full flight plans) at 0.5 Hz
- AFR:  Receive state and intent at 0.5 Hz

##  Experimental Design

**4 Conditions:**
**Baseline IFR: **L1 traffic, all managed
**Mixed 1: **L1 traffic, mixed operations
**Mixed 2: **L2 traffic, mixed operations
**Mixed 3: **L3 traffic, mixed operations
**T0: **Threshold approximating current day monitor alert parameter.
**T1: **Threshold above which managed-only operations may become unmanageable.

*Traffic counts to achieve these levels were established in simulation.*

- Traffic Level

## Task

**Center**

**TRACON**

**Center controllers are *****only***** alerted to imminent (<= 4 min.) autonomous-managed conflicts. **

- freeze horizon

**Task**

**If an autonomous aircraft cannot meet RTA, flight crew must alert controller ASAP. Workload permitting, the controller will accommodate by assigning new RTA, relaxing meter fix altitude or speed constraints, or sending aircraft across different fix.**

**Autonomous and managed aircraft merge at the meter fix. All aircraft are managed in the TRACON.**

**Transfer of communication uplink message is sent automatically to autonomous aircraft. Flight crew is instructed to “monitor” not “contact” next frequency..**

**Meter fix RTA is uplinked *****automatically***** to the autonomous aircraft at the freeze horizon. The RTA provides a merge slot for TRACON entry.**

**Autonomous aircraft are responsible for solving *****all***** conflicts.**

## Autonomous Flight Rules

- Autonomous Flight Rules were designed to ensure concept safety, and low impact on ATC operations. The AFR flight rules stated that AFR pilots
- May choose their own route and altitude.
- Must ensure separation of ownship from all other aircraft (5 NM lateral, 1000 ft vertical).
- Must give way to managed (IFR) aircraft.
- When burdened, must resolve a predicted conflict prior to 2 minutes to _l_oss _o_f _s_eparation (LOS). (AFR Rules of the Road, outlined in a separate presentation, determined which aircraft was burdened.)
- Must not create near-term conflicts (< 4 minutes) with any aircraft when maneuvering or changing flight modes.

## Autonomous Flight Rules (cont.)

- Must conform to arrival clearance at entry to TRACON
- RTA +/- 15 sec
- Altitude +/- 300 ft
- Speed +/- 10 kts
- Must notify ATSP if arrival clearance constraints cannot be met and request an amended clearance.

**Notes:**
Rules of the Road for maneuvering

## Ames Participants

- Ten air transport rated pilots with
-  experience in several previous DAG studies.
-  4,500 to 22,000 flight hours (mean ~ 11,000)
-  85 to 8,000 glass cockpit hours (mean ~ 4000)
- Eight pilots flew eight single pilot workstations.
- Two flew the full mission flight simulator, functioning as a two-pilot crew.

**Notes:**
All pilots were ATP rated and Instrument rated.
Pilots had an average of 12.5 hours per week of computer usage (not including email and web-browsing).
All of the pilots own their own computer.
Sixty percent of the pilots had previous military experience.
Two pilots had previous experience using a military display to monitor or maintain spacing from an aircraft.

## Ames Flight Deck Simulation Results

- Separation Management Metrics
- Meter Fix Conformance Metrics
- Subjective Ratings

## Separation Management Metrics

- The metrics used to evaluate separation management were based on
- AFR Flight Rules
- Losing Separation
- Creating Conflicts
- Resolving Conflicts
- Burdening (Rules of the Road)
- Good Practice
- Resolution Time Less than 2 min

## Separation Violations

**None**

## Conflict Detection and Resolution Times

**89% of all conflicts resolved within 2 minutes of detection**
**Almost all  near term conflicts (under 4 minutes) were arrivals.**
**4 due to AFR subject pilots**
**3 software malfunctions**
_***1 procedural error***_
**2 AFR failures to resolve by 2 minutes**
**1 software malfunction**
_***1 procedural error***_
**Note immediate resolutions on the main diagonal**

## Times Prior to Projected LOS When Conflict First Detected

**Creating Conflicts**

**AFR Flight Rules Prohibit Maneuvers which Create a Conflict with Less than 4 Minutes to LOS**
- Ames AFR participant aircraft violated this rule in 4 out of 139 conflicts. Of these
- Three violations were due to software errors
*** ******One violation was a procedural error***

## Time to LOS at Which Conflicts were Resolved

**Resolving Conflicts**

**AFR flight rules require that burdened aircraft resolve all conflicts prior to 2 minutes to LOS.**
- AFR participant aircraft violated this rule in 2 out of 123 conflicts where the participant aircraft was burdened.
- One violation was due to a conflict detection software flaw.
- The second violation was a procedural error associated with the aforementionned late maneuver into conflict incident

- Mixed L1

- Mixed L2

- Mixed L3

**Condition**

## Burdening

**Number of conflict resolutions as a function of burdening **

- While less than 7% of IFR aircraft resolved IFR-AFR  conflicts (IFR was never burdened), it is noteworthy that almost 1/3 of the non-burdened AFR aircraft resolved the AFR-AFR conflicts.

**AFR-AFR             AFR-AFR           AFR-IFR**
- Subject Pilot         Subject Pilot     AFR Always
- Not Burdened       Burdened         Burdened
-                            **Burdening**

**Burdening**

- Burdened Resolves

- Non-Burdened Resolves

## Meter Fix Conformance Metrics

**Speed Restriction**
**Altitude Restriction**
**RTA Restriction**

## Meter Fix Speed Compliance

- All but one Ames AFR participant aircraft met the speed restriction.
- The exception asked for and received a revised clearance.

- Airspeed (kts)

## Meter Fix Altitude Compliance

- All but one Ames AFR participant aircraft met the meter fix altitude restriction

- Altitude (ft)

## Meter Fix RTA Compliance

- All Ames AFR participant aircraft met the meter fix RTA restriction

## Subjective Ratings

## WorkloadModified Cooper Harper Ratings 

- Workload was higher for
- Mixed vs Managed conditions
- Arrivals vs Overflights
- But was well within the satisfactory range. There was also no evidence that workload increased with traffic density.

## AFR-IFR Operations Preference

**AFR-IFR Operations Preference**

- The majority of pilots preferred AFR over IFR operations for
- Safety
- Workload
- RTA
- Situational Awareness

## Conclusions

- From an airborne perspective this autonomous flight operation is
- Feasible
- Scaleable
- Safe
- Efficient
- The concept provided
- Complete intent
- Good situational awareness
- Low workload decision support tools
- However, future research is required to determine which of these is truly critical to the concept