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Managing Arrival Congestion
“Rushing to WaitVs.
Slowing to Save (Fuel)”
•Dave Knorr – FAA
• Liaison to DFS and Eurocontrol PRU
• CANSO Benchmarking and Environmental WG‘s
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Outline
• Part 1: Background and Motivation
• Part 2: Calculated Baseline Inefficiency
• Part 3: Estimating Terminal time and fuel savings from Speed reduction in Cruise
Many Thanks to Co-authors: Philippe Enaud, Xing Chen, Marc Rose, Holger Hegendorfer and
John Gulding
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Motivation
• Examples of Controlled Times of Arrival (CTA’s) to manage terminal area congestion:– ALOFT and MAESTRO Programs at Airservices Australia– Collaborative Flow Management – Airways NZ– NATS/United Trials into Heathrow – ATTILA with Delta into Atlanta– Morning Rush into Zurich– FAA ATTILA Trials at Charlotte– Tailored Arrivals into LAX and SFO– UPS use of ADS-B at Memphis– XMAN for FABEC…. And Lufthansa ASCAPE trials– Others??
• All cases motivated by fuel savings associated with incorporating FMS capabilities
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Improvement Pools for Time and Fuel Savings
Estimated Benefit Pool Actionable by ANSPs
Estimated Average Time (per flight)
Estimated Fuel Burn
Taxi ~5 min ~80 Kg*
Cruise ~3 min ~150 Kg
Approach
(100nm and in) ~3 min ~120 Kg
Averages for Busiest 34 airports in the US and Europe
GATE-to-GATEDEPARTURE
ANS-relatedHolding at theGate (ATFM/
EDCT)
Taxi-outefficiency
En-routeFlight
efficiency
IFR flightsTo/fromMain 34 airports
Efficiency In last
100NM
Taxi-inefficiency
IFR flightsTo/fromMain 34 airports
*Under Review
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Consider….
• In the US and Europe congestion management is applied based on projected arrival times
…… but mainly implemented through ground holds
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Consider….
Most flights receiving a ground delay will speed up (fly faster than cost index 0) after receiving a
ground delay
Premise for discussion:
Once an arrival time constraint is established - FUEL is the only variable left for an airline to optimize
(after safety)
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Additional time within the last 100NMGATE-to-GATEDEPARTURE
ANS-relatedHolding at theGate (ATFM/
EDCT)
Taxi-outefficiency
En-routeFlight
efficiency
Efficiency In last
100NM
0
2
4
6
8
10London
(LH
R)
Fra
nkf
urt
(FR
A)
Ath
ens
(AT
H)
Vie
nna
(VIE
)
Madrid
(MA
D)
Munic
h(M
UC
)
London
(LG
W)
Zurich
(ZR
H)
Geneva
(GV
A)
Nic
e (
NC
E)
Rom
e(F
CO
)
Duss
eld
orf
(DU
S)
Dublin
(DU
B)
Ham
burg
(HA
M)
Barc
elo
na
(BC
N)
Manch
est
er
(MA
N)
Mila
n(M
XP
)
Paris
(OR
Y)
London
(ST
N)
Osl
o (
OS
L)
min
ute
s p
er
arr
iva
lAverage additional time within the last 100NM miles
(only the first 20 airports in 2008 are shown)
Europe main 34 average (2.8 min.)
0
2
4
6
8
10
Phila
delp
hia
(PH
L)
New
York
(JF
K)
New
York
(LG
A)
New
ark
(EW
R)
Charlotte
(CLT
)
Atla
nta
(AT
L)
Mem
phis
(ME
M)
Bost
on
(BO
S)
Chic
ago
(OR
D)
Wash
ingto
n(I
AD
)
Balti
more
(BW
I)
Min
neapolis
(MS
P)
Chic
ago
(MD
W)
San
Fra
nci
sco
Tam
pa
(TP
A)
Orlando
(MC
O)
Wash
ingto
n(D
CA
)
Denve
r(D
EN
)
Seattle
(SE
A)
Phoenix
(PH
X)
min
ute
s p
er
arr
iva
l
US OEP 34 average (2.9 min.)
Source: FAA/ PRC analysis
•Top 68 Busiest Airports average 3 min of delay and 120Kg additional fuel on approach
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Congestion versus Flight Time
0 2 4 6 8 10 13 16 19 22 25 28 31 34
010
2030
4050
EGLL Jet
Arrival congestion
0 2 4 6 8 10 13 16 19 22 25 28 31 34
010
2030
4050
EGLL Jet
Arrival congestionNumber of aircraft in the arrival queue
Ave
rage
tran
sit t
ime
(100
nm to
land
ing)
Impact of congestion on the descent phase at London Heathrow airport (LHR)
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US and Europe - Establishing a Baseline
• How much time and fuel is currently spent absorbing delay on approach?
• Methodologies– Sample Airline data– Statistically based excess time using radar data, ac type and
crossing times– Converting excess distance and level segments to time and
fuel• Reduces impact of wind on estimates…
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•En-route•Flight
•efficiency
•Taxi-Out•efficiency
•Efficiency
•40 NM
•Taxi-In Efficiency
•Gate-to-Gate
•Efficiency •100NM
•Efficiency
•100NM
Inefficiency: Excess time in the last 100NM
•100 nmi
•40 nmi
•x
•Arrival
•Airport
•Arrival Fix
•Actual Route
•Notional Optimal
•Route•2.5%
•Direction of
•Flight
Originally Based on TAER Methodology – ATM2009
Updated to Better Account for Vertical Level-Offs – ATM2011
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50 Flights Active within 15 Minutes
A100 Measure Jan 15, 2009 12:30-12:45pm8 Arrivals in 15 Minutes
8.4 Minutes Average Inefficiency
40 nm
100 nm
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Inefficiency Detected from RADAR Data
Level SegmentsVertical Inefficiency
Direct FlightHorizontal Inefficiency
= ATC Constraints
Fuel (Act(x) – Fuel (Opt(x)
Fuel (Opt(x) – Fuel (Opt(x0)
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AAL 1612 763
0
5000
10000
15000
20000
25000
30000
35000
40000
-350 -300 -250 -200 -150 -100 -50 0
Distance from Touchdown (nm)
AL
titu
de
(ft)
TZ Trajectory Benchmark Trajectory
Vertical Component
di – distance of level seg.
hi – altitude of level seg.
hc – new altitude of level segment
N
ii
cii hvhvdT
1
))(/1)(/1(
))(/)()(/)((1
N
iii
ci
cii hvhfhvhfdF
T Change in Time
F Change in Fuel
v(h) – Speed at Alt h
f(h) – Fuelburn at Alt h
From BADA
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Horizontal Component
100nm circle
Unimpededtrajectory
Actualtrajectory
)( chv
ch - Cruise Altitude- Actual Distancex x0 - Minimum Distance
0DxDxD
*/ vDT ))()(/( cc hvhfDF
Nominal Speed at Cruise )( chf Nominal Fuel at Cruise
From BADA
v* benchmark speed from 100 nm to 40 nm for the group
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Example Calculation
NWA 1176 SWA 1132
SWA 186
“Un-Impeded”
•- 14 Min. “Delay”
- 6 Min. “Delay”
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Potential Benefit Pool Calculation
A100 VERTICAL HORIZONTAL excess distance
Carrier Flt. # AC Type Time (min) Fuel (kg) Time (min) Fuel (kg) Time (min) 100-40 (nm) 40-0 (nm)
NWA 1176 DC95 0.0 75.6 1.9 18.9 0.5 0.0 3.2
SWA 1132 B737 5.9 68.5 2.5 75.7 2.1 0.2 14.5
SWA 186 B733 14.0 90.4 4.9 241.0 5.8 0.0 39.9
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20091016 UAL870
Horizontal Calculation
100 to 40 excess distance: 0
40 to 0 excess distance: 0
Time improvement pool: 0
Fuel improvement pool: 0
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•20091016 UAL870 Vertical Calculation
Level distance: 0
Time saving pool: 0
Fuel saving pool: 0
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20090703 UAL870
Horizontal Calculation
100 to 40 excess distance: 0.42 nm
40 to 0 excess distance: 6.11 nm
Time saving pool: 0.93 minute
Fuel saving pool: 122.9 kg
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20090620 UAL870Vertical Calculation
Level distance: 19.1 nm
Time pool saving: 1.7 minute
Fuel saving pool: 160.7 kg
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Additional Fuel on Descent at Top 34 US Airports
0
50
100
150
200
250
EW
R
PH
L
LG
A
JFK
MD
W
ME
M
OR
D
AT
L
MS
P
BO
S
CL
T
DT
W
IAD
CV
G
IAH
DF
W
FL
L
BW
I
SF
O
DC
A
LA
S
PIT
ST
L
CL
E
MIA
DE
N
SE
A
PD
X
LA
X
SL
C
PH
X
TP
A
MC
O
SA
N
kg fuel
Horizontal Excess Fuel Vertical Excess Fuel
2009
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0
1
2
3
4
5
6
7
8
EW
RP
HL
LG
AJF
KM
DW
ME
MO
RD
AT
LM
SP
BO
SC
LT
DT
WIA
DC
VG
IAH
DF
WF
LL
BW
IS
FO
DC
AL
AS
PIT
ST
LC
LE
MIA
DE
NS
EA
PD
XL
AX
SL
CP
HX
TP
AM
CO
SA
N
Min
ute
s/A
rriv
al
0
10
20
30
40
50
60
Kilo
gram
s of F
uel (M
illion
s)
Total Excess Fuel Average Excess Time
Average Excess Time and Total Fuel by Facility
3.1 Minute Avg.
Total Fuel a Product of Time, Fleet Mix and Total Volume of Operations
JFKORD
ATL
DFW
2009
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The CASE for Speed Control in Cruise
• How much of the terminal area inefficiency can be recovered without changing throughput rates??
• Assumptions:– No speed adjustments for aircraft at the beginning of a “rush”– Used 1.5 to 5 minutes of absorbed delay as necessary for
keeping pressure on the runways aircraft/ANSP flow control based speed
– No fuel change estimated for slowing down in the cruise segment
– Assumed 30, 60, 90 and 120 minute windows for absorbing time in cruise
– If aircraft reaches cruise inside of 30 minutes left in cruise it is not considered in the pool
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SAMPLE Impact of Mach Speed on Fuel Burn
• Maximum Range (MR) is “Cost Index 0” and minimizes fuel burn
• Long range cruise (LRC) is a compromise between speed and fuel
• Going slower in cruise burns less fuel
….up to a point!
No fuel savings estimated for cruise speed reduction
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Methodology for Minutes of Cruise Delay Absorption
1. Calculate time in cruise for each flight• Remove Climb (15min) and last 100nm
• Establish variable for time available for speed reduction
2. Estimate potential time that can be absorbed for varying speed reductions
• Example…5% reduction on a 90 minute cruise time implies up to 4.7 minutes can be absorbed (90/0.95-90)
3. Time absorbed in cruise is the difference between Potential time above and the Excess (previous slide)
• Fuel Saved = Excess Fuel x time_saved/excess time
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Potential Time savings (US airports 2009)
0
1
2
3
4
5
6EW
RPH
LLG
AJF
KM
DW
MEM ORD ATL
MSP
BOS
CLT
DTW IA
DCV
GIA
HD
FW BWI
FLL
SFO
DCA LA
SPI
TST
LCL
ED
EN MIA
SEA
PDX
LAX
SLC
PHX
TPA
MCO
SAN
Exce
ss T
erm
inal
Tim
e (m
in/fl
ight
)
Total Excess Time
Speed Reduction: 8%Delay Threshold: 2.5 minMaximum Cruise: 90 min
0
1
2
3
4
5
6EW
RPH
LLG
AJF
KM
DW
MEM ORD ATL
MSP
BOS
CLT
DTW IA
DCV
GIA
HD
FW BWI
FLL
SFO
DCA LA
SPI
TST
LCL
ED
EN MIA
SEA
PDX
LAX
SLC
PHX
TPA
MCO
SAN
Exce
ss T
erm
inal
Tim
e (m
in/fl
ight
) Excess Time Shifted to CruiseNon-Recovered Excess Time
Speed Reduction: 8%Delay Threshold: 2.5 minMaximum Cruise: 90 min
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Potential Fuel savings (US airports 2009)
0
50
100
150
200
250EW
RPH
LLG
AJF
KM
DW
MEM ORD ATL
MSP
BOS
CLT
DTW IA
DCV
GIA
HD
FW BWI
FLL
SFO
DCA LA
SPI
TST
LCL
ED
EN MIA
SEA
PDX
LAX
SLC
PHX
TPA
MCO
SAN
Exce
ss T
erm
inal
Fue
l (kg
/flig
ht)
Total Excess Fuel
Speed Reduction: 8%Delay Threshold: 2.5 minMaximum Cruise: 90 min
0
50
100
150
200
250EW
RPH
LLG
AJF
KM
DW
MEM ORD ATL
MSP
BOS
CLT
DTW IA
DCV
GIA
HD
FW BWI
FLL
SFO
DCA LA
SPI
TST
LCL
ED
EN MIA
SEA
PDX
LAX
SLC
PHX
TPA
MCO
SAN
Exce
ss T
erm
inal
Fue
l (kg
/flig
ht)
Excess Fuel RecoveredRemaining Excess Fuel
Speed Reduction: 8%Delay Threshold: 2.5 minMaximum Cruise: 90 min
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Potential Savings vs Allowable Speed Reduction
0%
5%
10%
15%
20%
25%
30%
4% 5% 6% 7% 8% 9% 10% 11% 12%
Maximum Speed Reduction (%)
Po
rtio
n o
f E
xc
es
s T
erm
ina
l Sa
ve
d (
%)
Fuel
Time
Delay Threshold: 2.5 minMaximum Cruise: 90 min
32Federal AviationAdministration
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0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
40 50 60 70 80 90 100 110 120Maximum Cruise Time Available to Absorb Terminal Delay (minutes)
Perc
ent T
ime
and
Fuel
Fuel (1.5)
Time (1.5)
Fuel (2.5)
Time (2.5)
Fuel (5)
Time (5)
US - 5% max speed reduction
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
40 50 60 70 80 90 100 110 120Maximum Cruise Time Available to Absorb Terminal Delay (minutes)
Perc
ent T
ime
and
Fuel
Fuel (1.5)
Time (1.5)
Fuel (2.5)
Time (2.5)
Fuel (5)
Time (5)
33Federal AviationAdministration
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0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
40 50 60 70 80 90 100 110 120Maximum Cruise Time Available to Absorb Terminal Delay (minutes)
Perc
ent T
ime
and
Fuel
Fuel (1.5)
Time (1.5)
Fuel (2.5)
Time (2.5)
Fuel (5)
Time (5)
US - 8% max speed reduction
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
40 50 60 70 80 90 100 110 120Maximum Cruise Time Available to Absorb Terminal Delay (minutes)
Perc
ent T
ime
and
Fuel
Fuel (1.5)
Time (1.5)
Fuel (2.5)
Time (2.5)
Fuel (5)
Time (5)
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Potential time savings (Europe 2009)
0
1
2
3
4
5
6
7
8L
HR
FRA
VIE
MA
DZ
RH
MU
CA
TH
LG
WO
RY
HA
MFC
OG
VA
DU
SB
CN
CD
G LIS
MX
PPR
AM
AN
OL
SD
UB
STN
PMI
AM
SB
RU
CPH TX
LA
RN
potential time savings
additional time less potential savings
Source : CFMU, Year 2009
Add
ition
al ti
me
[min
utes
/arr
ival
]
Speed reduction: 5%Delay threshold: 1.5 minutesMaximum cruise: 90 minutes
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Potential fuel savings (Europe 2009)
050
100150200250300350400450
LH
RFR
AV
IEM
AD
ZR
HM
UC
AT
HL
GW
OR
YH
AM
FCO
GV
AD
US
BC
NC
DG LIS
MX
PPR
AM
AN
OL
SD
UB
STN
PMI
AM
SB
RU
CPH TX
LA
RN
potential fuel savings
additional fuel less potential savings
Source : CFMU, Year 2009
Add
ition
al fu
el [k
ilogr
am/a
rriv
al]
Speed reduction: 5%Delay threshold: 1.5 minutesMaximum cruise: 90 minutes
36Federal AviationAdministration
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Europe 2009 - 5% speed reduction
0%
10%
20%
30%
40%
50%
30 50 70 90
Fuel (1.5)
Time (1.5)
Fuel (2.5)
Time (2.5)
Terminal time absorbed in cruise with fuel saving (%)- 5% speed reduction -
Maximum Cruise Time Available To Absorb Terminal Delay (min)
Perc
ent t
ime
& fu
el
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Europe 2009 - 8% speed reduction
0%
10%
20%
30%
40%
50%
30 50 70 90
Fuel (1.5)
Time (1.5)
Fuel (2.5)
Time (2.5)
Terminal time absorbed in cruise with fuel saving (%)- 8% speed reduction -
Maximum Cruise Time Available To Absorb Terminal Delay (min)
Perc
ent t
ime
& fu
el
38Federal AviationAdministration
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Challenges
• Need better data on fuel saved by slowing in cruise• Implementation Issues remain with:
– moving outside an Individual ANSP or Center’s sphere of influence
– how to get times to pilots– how to enforce time windows (CTAs)– combining speed control with ground holds for shorter flights – how to handle equity and airline preferences for individual
flights– conflict resolutions in cruise impact on achieving CTAs– controller roles and acceptance
• Role of Simulations?• Additional Trials?
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Conclusions
• Potential pools for saving fuel thru speed changes can be estimated with basic ANSP data
• Fuel savings can be achieved through speed control in cruise– Fuel can be saved both through slowing down and reducing
excess time in the terminal area– Fuel Savings from speed control is achieved without increasing
capacity or throughput
• Worldwide implementation of CTA’s is growing and proving that fuel can be saved with speed adjustments today (without the benefit of full 4D trajectory management)
41Federal AviationAdministration
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Fuel savings from speed control versus flight length (Europe 2009)
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
<200 200-300 300-400 400-500Flight distance
Time (0.08)
Fuel (0.08)
Time (0.05)
Fuel (0.05)
% ti
me
and
fuel
Terminal Time Absorbed in Cruise with Fuel Saving (%)
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Example Calculation
NWA 1176 SWA 1132
SWA 186
“Un-Impeded”
- 14 Min. “Delay”
- 6 Min. “Delay”
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Benefit Calculation
A100 VERTICAL HORIZONTAL excess distance
Carrier Flt. # AC Type Time (min) Fuel (kg) Time (min) Fuel (kg) Time (min) 100-40 (nm) 40-0 (nm)
NWA 1176 DC95 0.0 75.6 1.9 18.9 0.5 0.0 3.2
SWA 1132 B737 5.9 68.5 2.5 75.7 2.1 0.2 14.5
SWA 186 B733 14.0 90.4 4.9 241.0 5.8 0.0 39.9
47Federal AviationAdministration
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ANSP Quality of Service has 4 primary focus areas
1. Availability of Direct or Wind Optimal Routes
2. Maximizing Capacity and Throughput (Terminal and En Route)
3. Resilience of Capacity (IMC like VMC, time based separation for wind reduced capacity on final)
4. Managing necessary delay in the most fuel efficient manner (Measuring delay by phase of flight)
48Federal AviationAdministration
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Calculating Potential Benefits from Reduced Speed in Cruise
Methodology
• Start with total excess terminal time on a per flight basis– Remove additional
terminal time to keep pressure on runways
(1.5, 2.5, & 5min)
• Establish estimate for potential time absorption in cruise
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Excess Minutes
Per
cen
tag
e
Additional Terminal Time into SFO
Example
Excess Minutes