Stabilized Landings - Charbonneau CASS 2010
Stabilized Landing
Concept
A Runway Excursion Prevention Tool
NBAA 2010
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Stabilized Landings - Charbonneau CASS 2010
Steve Charbonneau
Altria Client Services Inc
Sr. Manager Aviation Safety and Security
Steve.Charbonneau@Altria.com
804-218-9165
Located in Richmond, Virginia
Operate:
1 G550
2 G450
2
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Stabilized Landings - Charbonneau CASS 2010
Introduction
ƒ Stabilized Approach Criteria has successfully
elevated the in-cockpit awareness of risky
approaches
ƒ Programs such as FOQA monitor stabilized approach
rates – and go around rates
ƒ Go-around rates following un-stabilized approaches
are low
ƒ This presentation investigates and proposes the
concept of Stabilized Landing criteria.
3
This presentation investigates and proposes the concept of Stabilized Landing criteria.
Conceptually, stabilized landing criteria establish the performance requirements for
landings from the threshold to the end of the landing roll out. The stabilized landing
concept serves to reinforce the requirement for pilots to perform landings in
accordance with aircraft performance certification, FAA guidelines and industry
standard best practices, similarly as with the stabilized approach criteria. The purpose
of this presentation is to define and present the elements of a stabilized landing.
Additionally, to propose that pilots seek to achieve successful landings by combining
the elements of stabilized approach and stabilized landing criteria.
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Stabilized Landings - Charbonneau CASS 2010
Major References
ƒ Flight Safety Foundation. (2010) Approach and Landing
Accident Reduction Toolkit Update
ƒ Flight Safety Foundation. (2009). Reducing the Risk of
Runway Excursions. Runway Safety Initiative Report
ƒ US DOT. Federal Aviation Administration. (11/06/07).
Advisory Circular 91-79. Runway Overrun Prevention
ƒ US DOT. Federal Aviation Administration.
(6/3/99).Advisory Circular 25-7A Change 1. Flight Test
Guide for the Certification of Transport Category
Airplanes
4
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Stabilized Landings - Charbonneau CASS 2010
Outline
ƒ Consider the Flight Safety Foundation data
for Runway Excursions
ƒ Understand landing certification concepts
ƒ Look into threats to safe landings
ƒ Define Stabilized Landing Concept and identify Criteria
ƒ Demonstrate how C-FOQA can reveal opportunities to
improve
5
Stabilized landing criteria are derived from guidelines established by the FAA,
manufacturer’s performance certification data, safety research, and empirical data
gathered from review of Corporate Flight Operations Quality Assurance (hereafter CFOQA) reports. It considers the effects of excessive height, airspeed, groundspeed,
landing beyond the touchdown zone, and insufficient or ineffective braking. Each of
the criteria will need to be met, within reasonable tolerances, in order for a landing to
be considered as stabilized. Once the concept of stabilized landings is defined, this
presentation serves to reinforce the benefits of monitoring both stabilized approaches
and landings using a flight operations quality assurance program, such as C-FOQA.
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Stabilized Landings - Charbonneau CASS 2010
Approach and Landing Accidents, by Year
6
The trend line, calculated using least squares linear regression, indicates that the
absolute number of approach and landing accidents gradually decreased during the
study period.
6
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Stabilized Landings - Charbonneau CASS 2010
FSF Data: All Approach and Landing Accidents
1995-2007
Approach
Final approach
Landing
Other
Unknown
Flight phase
Figure 1: FSF ALAR Update - Killers in Aviation Update Pg. 5
7
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Stabilized Landings - Charbonneau CASS 2010
Most Common Types of
Approach and Landing Accidents
1995–2007
• Landing veer‐off
• Landing overrun
• Unstabilized approach
• Controlled flight into terrain (CFIT)
• Collision with terrain, non‐CFIT
• Runway undershoot
These comprise 77 percent of the total approach and landing accidents.
8
These were the most common types of approach and landing accidents (ALAs)
found in the 2009 study. Runway excursions, comprising veer-offs and overruns,
account for approximately 45 percent of all ALAs. Some accidents can be
categorized as more than one type.
8
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Stabilized Landings - Charbonneau CASS 2010
Runway Excursion
ƒ According to the Flight Safety Foundation, a runway
excursion occurs when an aircraft on a runway surface
departs the end or the side of that runway surface.
ƒ Runway excursions can occur on takeoff or landing
– Veer Off – Depart the side of the runway
– Overrun – Depart the end of the runway
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(FSF.ALAR Briefing Note 8.1, p.159).
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Stabilized Landings - Charbonneau CASS 2010
Runway Excursion Accidents
Figure 2: Proportion of Fatal and Non Fatal Accidents (FSF, 2009, RSI Report, p. 5)
10
The FSF Report of the Runway Safety Initiative (RSI) published May, 2009
documented alarming evidence that from 1995-2008, runway related accidents
accounted for a full 30% of all commercial transport category aircraft; furthermore,
runway excursion accidents represented 97% of those accidents.
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Stabilized Landings - Charbonneau CASS 2010
Runway Excursion Accidents
Runway Excursions 1995-2008
20
07
20
05
20
03
20
01
19
99
Number of
Accidents
Trend
19
97
19
95
45
40
35
30
25
20
15
10
5
0
Figure 3: Runway Excursions 1995-2008 (FSF, 2009, RSI Report, p. 6)
11
Considering the last 14 years, it appears that the trend has bottomed overall;
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Stabilized Landings - Charbonneau CASS 2010
Runway Excursion Accidents
Runway Excursions 2004-2008
50
40
Number of
Accidents
Trend
30
20
10
0
2004
2005
2006
2007
2008
Figure 4: Runway Excursions 2004-2008 (FSF, 2009, RSI Report, p. 6)
12
However, a closer look at the last 5 years, 2004-2008, reveals that the trend is
climbing (FSF, 2009, RSI Report, p. 6). In 2009, the year over year results show an
18% reduction in the number of accidents; although, the overall percentage of runway
excursion accidents still accounted for some 26% of all accidents, repeating the 2008
results. (IATA.ORG, Feb. 2010, Press Release No. 5).
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Stabilized Landings - Charbonneau CASS 2010
Runway Excursion Accidents
Runway Excursions - 1995-2008
500
400
300
200
21%
79%
100
0
Takeoff
Landing
Figure 5: Runway Excursion by Type (FSF, 2009, RSI Brief)
13
According to the FSF the majority (79%) of runway excursion accidents occur in the
landing phase with a near balance of overruns and veer offs.
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Stabilized Landings - Charbonneau CASS 2010
Runway Excursion Factors
ƒ The FSF cites the major risk factors in landing excursions
were:
– go-around not conducted,
– long landings,
– ineffective braking (contaminated runways),
– gear malfunctions, and
– fast approaches and landings.
14
The FSF cites the major risk factors in landing excursions were: go-around not
conducted, long landings, ineffective braking (contaminated runways), gear
malfunctions and fast approaches and landings. IATA has determined that unstabilized approaches, failure to conduct a go-around, abnormal touchdowns, and
contaminated runways were the major contributors to landing excursions (IATA.ORG
– Fact Sheet). Clearly, the risk factors have been well documented and published by
the ALAR and RERR Toolkits.
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Stabilized Landings - Charbonneau CASS 2010
Outline
ƒ Consider the Flight Safety Foundation data for Runway
Excursions
ƒ Understand landing certification concepts
ƒ Look into threats to safe landings
ƒ Define Stabilized Landing Concept and identify Criteria
ƒ Demonstrate how C-FOQA can reveal opportunities to
improve
15
Stabilized landing criteria are derived from guidelines established by the FAA,
manufacturer’s performance certification data, safety research, and empirical data
gathered from review of Corporate Flight Operations Quality Assurance (hereafter CFOQA) reports. It considers the effects of excessive height, airspeed, groundspeed,
landing beyond the touchdown zone, and insufficient or ineffective braking. Each of
the criteria will need to be met, within reasonable tolerances, in order for a landing to
be considered as stabilized. Once the concept of stabilized landings is defined, this
presentation serves to reinforce the benefits of monitoring both stabilized approaches
and landings using a flight operations quality assurance program, such as C-FOQA.
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Stabilized Landings - Charbonneau CASS 2010
Landing Certification
ƒ FAR Section 25.125 specifies the requirement to provide landing
distances, defined as the horizontal distance necessary to land
from a point 50 feet above a dry hard surface and come to a
complete stop.
ƒ The aircraft must be in the landing configuration, having flown a
stabilized approach at a speed of not less than VREF down to
the 50 foot height, amongst other requirements.
ƒ The Flight Test Guide for the Certification of Transport Category
Airplanes, Advisory Circular 25-7A, provides manufacturers with
guidance to ensure compliance with the regulations.
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It states that the landing must be made without excessive vertical acceleration and the
pressures on the wheel braking systems may not exceed those specified by the brake
manufacturer. The landing distance data must also include correction factors for not
more than 50 percent of head wind components and not less than 150 percent of the
tail wind component.
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Stabilized Landings - Charbonneau CASS 2010
Landing Certification
ƒ Distances are treated in two parts:
– the airborne distance from 50 feet to touchdown, and
– the ground distance from touchdown to stop
Airborne
Ground
17
The guide details the test and demonstration requirements for manufacturers during
certification. It is interesting to note that for landing performance, distances are treated
in two parts: the airborne distance from 50 feet to touchdown, and the ground distance
from touchdown to stop (AC 25-7A, Chap. 2, p. 98).
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Stabilized Landings - Charbonneau CASS 2010
Landing Certification
ƒ Airborne Distance
– 3 or 3½ degree approach path
– Sink rates as much as 8 feet per second at touchdown
(480 fpm)
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The test guide allows for airborne distances to be calculated at 3 or 3½ degrees, given
appropriate requirements are met, with sink rates at touchdown as much as 8 feet per
second. For example, the Gulfstream G-550 aircraft has been certified with a 3½º and
8 feet per second descent giving the shortest possible airborne distance (G-550, AFM
Rev 29, Chap. 5, p. 05-120).
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Stabilized Landings - Charbonneau CASS 2010
Landing Certification
ƒ Ground Distance
ƒ Transition within 2 secs
ƒ Based on FULL Braking
Figure 6 Landing Time Delays (AC 25-7a, p. 103)
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In the ground distance calculation, the test guide allows for the use of transition
distances, which is the distance from the point of touchdown to the full braking
configuration, and stopping distances; or, a combination of the two, whichever is
preferred by the applicant (AC 25-7a, p. 101). In either case, it is critical to note that
the ground distance is based upon the aircraft decelerating with maximum allowable
brake pressure and other aerodynamic devices deployed within two seconds or less
after touchdown, as the test guide permits for manufacturers to reduce the two second
delay by expanding the AFM data when seeking credit for automatic deceleration
devices.
Figure 4 Landing Time Delays (AC 25-7a, p. 103)
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Stabilized Landings - Charbonneau CASS 2010
“Landing distances determined
during certification are aimed at
demonstrating the shortest landing
distances… Therefore, the landing
distances determined under FAR
23.75 and 25.125 are much shorter
than the landing distances achieved
in normal operations”.
(AC 91-79, App. 1, p. 8)
They further amplify that “The importance of adhering to the landing procedures
outlined in the AFM cannot be overemphasized… The AFM assumes that the
deceleration devices will be fully deployed by 2 seconds after touchdown… The
maximum braking condition is assumed to be maintained until the airplane reaches a
full stop (AC 91-79, 11/06/07, App. 3, p. 3)”.
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Stabilized Landings - Charbonneau CASS 2010
Outline
ƒ Consider the Flight Safety Foundation data for Runway
Excursions
ƒ Understand landing certification concepts
ƒ Look into threats to safe landings
ƒ Define Stabilized Landing Concept and identify Criteria
ƒ Demonstrate how C-FOQA can reveal opportunities to
improve
21
Stabilized landing criteria are derived from guidelines established by the FAA,
manufacturer’s performance certification data, safety research, and empirical data
gathered from review of Corporate Flight Operations Quality Assurance (hereafter CFOQA) reports. It considers the effects of excessive height, airspeed, groundspeed,
landing beyond the touchdown zone, and insufficient or ineffective braking. Each of
the criteria will need to be met, within reasonable tolerances, in order for a landing to
be considered as stabilized. Once the concept of stabilized landings is defined, this
presentation serves to reinforce the benefits of monitoring both stabilized approaches
and landings using a flight operations quality assurance program, such as C-FOQA.
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Stabilized Landings - Charbonneau CASS 2010
Threats to Safe Landings
According to AC 91-79:
ƒ Un-stabilized Approach
ƒ Excess Airspeed
ƒ Excess Threshold Crossing Height
ƒ Landing Long (Beyond the touchdown zone)
ƒ Adverse wind conditions
ƒ Failure to assess required landing distance
RERR provides an excellent Threat Analysis presentation
22
FAA AC 91-79 identified the major risks to runway excursions. Specifically it
highlighted: a non-stabilized approach, excess airspeed, landing beyond the intended
touchdown point, and failure to assess the required landing distance to account for
contamination or the landing environment (AC 91-79, p. 3). The advisory circular went
further to provide specific risk mitigation recommendations as well as comprehensive
additional information including guidance on regulatory interpretation and technique.
The Runway Excursion Risk Reduction Toolkit offers an excellent presentation
on Managing the Risks During Approach and Landing: How to Avoid a Runway
Overrun
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Stabilized Landings - Charbonneau CASS 2010
Un-stabilized Approach
ƒ Un-stabilized approaches typically co-exist with other risk
factors
– According to the RSI unstable approaches were a factor in:
ƒ 88% of long/fast overrun accidents, and
ƒ 51% of hard landing veer off accidents
ƒ There are strong associations with unstable approaches and
long/hard/fast landings
ƒ Failure to Go-Around contributed to one-third of all landing
excursion accidents.
ƒ Could be avoided by a go-around as required with stabilized
approach criteria
23
The FSF RSI report indicated that the failure to go-around following an un-stabilized
approach contributed to one-third of all landing excursion accidents. Furthermore, the
resulting landing attempt contributed to long landings, fast approaches, and fast and
hard touchdowns. Complicating the issue with un-stabilized approaches is the fact that
they typically co-exist with other risk factors; for example, unstabilized approach was
cited in 77 of 87 long/fast overrun landing events (88%), and 20 of 39 hard landing
veer off events (51%).
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Stabilized Landings - Charbonneau CASS 2010
Un-stabilized Approach
ƒ Why do pilots continue to attempt to salvage unstabilized
approaches?
ƒ Four possible behaviors:
– excessive confidence in a quick recovery;
– excessive confidence because of runway or environmental
conditions;
– inadequate preparation or lack of commitment to conduct a goaround; or,
– absence of decision because of fatigue or workload
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The question remains, why do pilots continue to attempt to salvage unstabilized
approaches? The ALAR Toolkit indicated four possible behaviors: excessive
confidence in a quick recovery; excessive confidence because of runway or
environmental conditions; inadequate preparation or lack of commitment to conduct a
go-around; or, absence of decision because of fatigue or workload (ALAR, Briefing
Note 7.1, p. 136).
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Stabilized Landings - Charbonneau CASS 2010
Excess Airspeed
ƒ Excess airspeed has been a cause factor in nearly 15% of
landing excursion accidents
ƒ The performance data is normally based upon Vref not
Vapp at a height of 50 feet above the threshold
– Corrections to Vref are meant to be bled off to arrive at
threshold on speed
ƒ Excess Speed affects either airborne or ground landing
distances – or both
25
Typically, the Vref speed is used to determine an approach speed which is maintained
while on final approach in the landing configuration. Normally five or ten knots is
added to the Vref speed, and perhaps also corrected for strong or gusty winds, or
other conditions. The approach speed; however, must be reduced to Vref to cross the
threshold at the 50 foot crossing height, as the performance data is based upon that
speed.
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Stabilized Landings - Charbonneau CASS 2010
Excess Airspeed
ƒ Airborne Landing Distance Effects:
– 230 feet per knot of increased landing flare distance
ƒ Ground Landing Distance Effects (Dry):
– 20-30 feet per knot of increased landing distance
ƒ Ground Landing Distance Effects (Wet):
– 40-50 feet per knot of increased landing distance
26
AC 91-79 provides a breakdown of the increased landing distances as follows:
Airborne Distance – 230 feet per knot of increased landing flare distance; or
Ground distance – Dry – 20-30 feet per knot of increased landing distance; or
Ground distance – Wet – 40-50 feet per knot of increased landing distance;
Note: Ground distance – Contaminated – not indicated in the circular.
For example, an approach with 10 knots of excess airspeed at the 50 threshold
crossing height may result in a 2300 foot extended flare or a 200-300 foot increased
landing roll.
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Stabilized Landings - Charbonneau CASS 2010
Excess Airspeed
ƒ A 10 knot excess airspeed has the potential of extending
the landing distance by
– 2300 feet with an extended float/flare; or
– 200-300 feet (dry) with a fly on landing in the touchdown zone
ƒ Floating the landing has a 10X effect on landing distances
27
For example, an approach with 10 knots of excess airspeed at the 50 threshold
crossing height may result in a 2300 foot extended flare or a 200-300 foot increased
landing roll. It is important to note that the effects of excess airspeed at the
threshold are ten times greater if the pilot elects to bleed the energy off in the
flare, rater than flying the airplane onto the runway and promptly transitioning
to the braking configuration. If the operator had a hypothetical 3000 foot dry landing
distance; then the 10 knot excess airspeed would have resulted in an actual landing
distance of up to 5300 feet. Even if the operator is in the habit of factoring landing
distances, or adding safety margins, this seemingly innocuous airspeed error would
have greatly reduced those expected margins.
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Stabilized Landings - Charbonneau CASS 2010
Excess Threshold Crossing Height
ƒ Represents a high energy situation which logically will
result in an extended airborne landing distance or ground
roll out
ƒ AC 91-79 estimates that this distance is equivalent to 200
feet for each 10 feet of excess TCH
50’ TCH = 1000’
100’ TCH = 2000’
150’ TCH = 3000’
28
A TCH of 100 feet would extend the landing distance by 1000 feet (AC 91-79, p. 10).
Excess TCH normally leads to long landings, beyond the desired touchdown point, as
the pilot seeks to maintain a continuous stabile approach angle to a revised aim point,
increasing the airborne distance; or, noses over the aircraft to achieve the desired
touchdown point thus increasing the airspeed and the ground roll distance.
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Stabilized Landings - Charbonneau CASS 2010
Landing Long
ƒ Shallow approaches will also increase the airborne
distance, as will a negative slope on the runway;
approximately adding a 10% penalty to landing distances
ƒ Pilots should seek to accomplish firm landings in the
landing zone; which is defined as the first third, or 3000
feet of the runway whichever is less.
29
While excess airspeed and high TCH may contribute to landing beyond the touchdown
point, other potential contributors are negative runway slope, shallow approach,
tailwind conditions and landing technique. While most airplanes are certified to
touchdown following a 3 or 3½ degrees approach slope with as much as an 8 foot per
second sink rate, it is rare that pilots will operationally use this same technique. As
AFM landing distance calculations are based upon this technique, pilots must make
efforts to achieve touchdowns close to the intended touchdown point; otherwise,
landing distances will not be accurate.
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Stabilized Landings - Charbonneau CASS 2010
Landing Long
The Touchdown Zone
ƒ Most airplanes are certified to touchdown following a
3 or 3½ degrees approach slope with as much as an 8
foot per second sink rate (480 FPM), giving
ƒ Touchdown points approximately 1000 feet from the
threshold
ƒ Painted Runway Marking aim points are depicted at
approximately 1000 feet from the threshold, which
corresponds to most type certifications
ƒ Touchdown Zones – 1000-1500 from threshold –
allows for cushioned landings
30
While excess airspeed and high TCH may contribute to landing beyond the touchdown
point, other potential contributors are negative runway slope, shallow approach,
tailwind conditions and landing technique.
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Stabilized Landings - Charbonneau CASS 2010
Landing Long - The Common Culprit
ƒ The RSI determined that long landings were strongly
associated with each of the other risk factors during
overrun excursions, including:
– Unstabilized approaches – 77 of 87 events (88%)
– Hard Landing/Bounce – 15 of 17 events (88%)
– Go-Around not conducted – 91 of 107 events (85%)
– Tailwind conditions – 20 of 30 events (67%)
– Gusty or wind-shear conditions – 14 of 22 events (64%)
– Contaminated Runways conditions – 53 of 101 events (52%)
– Crosswind events – 9 of 18 events (50%)
31
The RSI determined that long landings were strongly associated with each of the other
risk factors during overrun excursions, including:
Unstabilized approaches – 77 of 87 events (88%)
Hard Landing/Bounce – 15 of 17 events (88%)
Go-Around not conducted – 91 of 107 events (85%)
Tailwind conditions – 20 of 30 events (67%)
Gusty or wind-shear conditions – 14 of 22 events (64%)
Contaminated Runways conditions – 53 of 101 events (52%)
Crosswind events – 9 of 18 events (50%)
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Stabilized Landings - Charbonneau CASS 2010
Adverse wind conditions
Tailwinds on Landing
ƒ Most aircraft are certified with 10 or 15 knots maximum
tailwind
ƒ Tailwind conditions serve to increase the groundspeed
which extends the airborne distance during the flare
ƒ Any tailwind on contaminated runways is not encouraged
due to the inherent hazards
32
Tailwind conditions can also complicate landings when they co-exist with other risk
factors, such as contaminated runway conditions. Indeed, manufacturers will often
have specific limitations prohibiting tailwind conditions when contaminated runway
conditions are present. Gulfstream specifically cautions operators, “Operations with
any tailwind on contaminated runways is not encouraged due to the inherent hazards
of operating on such runways”
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Stabilized Landings - Charbonneau CASS 2010
Adverse wind conditions
Crosswinds and Gusts on Landing
ƒ According to the RSI report, crosswinds, wind gusts and
turbulence are also associated with runway excursion
accidents. They contributed to:
– 16 of 18 (89%) of overrun excursions, and
– 22 of 47 (47%) of veer off landing excursions
ƒ Adverse wind conditions were involved in 33% of
accidents between 1984-1997, and
ƒ When wet runways co-existed, adverse winds were
involved in the majority of the runway excursions
33
Pilots must consider that when adverse wind conditions are combined with adverse
runway surface conditions they should seek alternative runways with preferable
conditions.
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Stabilized Landings - Charbonneau CASS 2010
Adverse wind conditions
Crosswinds and Wet/Contaminated Runway
ƒ Assess the runway condition
ƒ Apply correction factors
using chart
ƒ ALAR Toolkit provided
detailed guidance concerning
landings in crosswind
conditions (ALAR, 8.7)
Figure 7 GIV - QRH - PA-3
34
If landings must be conducted, pilots are strongly encouraged to consult tools such as
the Gulfstream Crosswind Limits Based on the Canadian Runway Friction Index or
Braking Coefficient Chart and have a plan to go around should the landing prove to be
hazardous.
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Stabilized Landings - Charbonneau CASS 2010
Failure to assess required landing distance
ƒ 50 percent of the operators surveyed did not have
adequate policies in place for assessing whether
sufficient landing distance exists at the time of arrival at
the destination airport (AC 91-79)
ƒ Two fundamental elements;
– Correctly assessing the environmental conditions of the
runway, and
– Properly assessing the correct aircraft performance given the
actual runway conditions
35
“A survey of numerous operators’ Flight Operations or General Operating Manuals by
the FAA’s Landing Performance Team indicated that approximately 50 percent of the
operators surveyed did not have adequate policies in place for assessing whether
sufficient landing distance exists at the time of arrival at the destination airport” (AC
91-79, App. 1, p. 7).
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Stabilized Landings - Charbonneau CASS 2010
Failure to assess required landing distance
ƒ Operators need to develop policies to compel flight crew
to verify the runway condition prior to landing and apply
sufficient safety margins to certified landing distances
ƒ The use of factored landing distances can assist with the
ease of in-cockpit calculations (ALAR 8.3)
ƒ It is critical that pilots understand that AFM landing
distances are based upon landings which are not normally
operationally achievable and represent the starting point
for determining accurate landing distances
36
As most certified landing performance does not include wet or contaminated data, unapproved data offered by the manufacturer should be used to determine landing
distance requirements. Often, those data are not easily accessible in the cockpit as
the data cannot be programmed into flight management system computers. Operators
need to ensure that methodology is developed to allow crews to quickly refer to data
and apply it to landing distance calculations.
The ALAR Toolkit Briefing Note 8.3 provides a quick reference for pilots when
considering landing distance factors. Pilots should be cautioned that simply factoring
dry landing distances will only account for the known and planned performance
deviations; unplanned deviations may quickly squander any/all safety margins and
pilots should always strive to achieve planned performance distances.
AC 91-79 Appendix 1 is an excellent reference to understand the complexities of
landing distance calculations.
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Stabilized Landings - Charbonneau CASS 2010
Top Five Causal Factors of Approach and Landing
Accidents
Slow/
delayed
reaction
Aircraft
handling
Failure in CRM
Poor
professional
judgment/
airmanship
Omission
of action/
inappropriate
action
Causal factor
CRM = crew resource management
37
This slide shows the top five causal factors of approach and landing accidents from
1995 through 2007.
37
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Stabilized Landings - Charbonneau CASS 2010
Top Five Circumstantial Factors in Approach and
Landing Accidents
Training
inadequate
Runway
contamination
Poor
visibility
Other
weather
factors
CRM failure
Circumstantial factor
CRM = crew resource management
38
This slide shows the five most frequent circumstantial factors in approach and
landing accidents.
38
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Stabilized Landings - Charbonneau CASS 2010
Consequences of Approach and Landing Accidents
Loss of
control
in flight
Post‐impact Undershoot
Ground
fire
collision
with object
Collision
(non‐CFIT)
CFIT
Overrun
Veer‐off
Accident consequence
CFIT = controlled flight into terrain
39
Not shown on this slide is the most frequent — and obvious — consequence of
ALAs: significant damage to the airplane, which was the result of 466, or 46
percent, of the 1,007 approach and landing accidents in 1995–2007.
39
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Stabilized Landings - Charbonneau CASS 2010
Outline
ƒ Consider the Flight Safety Foundation data for Runway
Excursions
ƒ Understand landing certification concepts
ƒ Look into threats to safe landings
ƒ Define Stabilized Landing Concept and identify Criteria
ƒ Demonstrate how C-FOQA can reveal opportunities to
improve
40
Stabilized landing criteria are derived from guidelines established by the FAA,
manufacturer’s performance certification data, safety research, and empirical data
gathered from review of Corporate Flight Operations Quality Assurance (hereafter CFOQA) reports. It considers the effects of excessive height, airspeed, groundspeed,
landing beyond the touchdown zone, and insufficient or ineffective braking. Each of
the criteria will need to be met, within reasonable tolerances, in order for a landing to
be considered as stabilized. Once the concept of stabilized landings is defined, this
presentation serves to reinforce the benefits of monitoring both stabilized approaches
and landings using a flight operations quality assurance program, such as C-FOQA.
40
Stabilized Landings - Charbonneau CASS 2010
Stabilized Landing
ƒ A landing conducted where the aircraft is positively
controlled from a point 50 feet above the threshold to
a full stop on the landing surface, without any
unintended or adverse aircraft deviations from the
planned and briefed maneuver.
41
Arriving at the threshold, following a stabilized approach, represents the
transition point from the approach to the landing phase of flight. It is
also the last opportunity for the pilot to assess the performance conditions
and determine if it is safe to continue the landing; or, should the flight
parameters be not as briefed or desired, conduct an immediate goaround.
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Stabilized Landings - Charbonneau CASS 2010
Stabilized Landing Criteria
ƒ A landing is stabilized when all of the following criteria are met:
– The runway conditions are properly assessed and a realistic
landing distance calculation, with appropriate safety margin,
is planned and briefed (landing strategy);
– The aircraft achieves a threshold crossing height of 50 feet;
– The aircraft speed at the threshold is not more than Vref + 5
knots;
– Tailwind conditions not more than 10 knots for a dry runway,
and nil for a wet or contaminated runway;
– The aircraft touches down firmly in the landing zone and is
promptly transitioned to the desired braking condition; and
– The aircraft is slowed to a speed of not more than 80 knots
with not less than 2000 feet runway remaining.
42
The fundamental principle of strategy planning is: plan for the worst – hope for the
best. This principle allows for the maximum margin for error.
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Stabilized Landings - Charbonneau CASS 2010
Stabilized Landing Criteria
ƒ A landing that is not stabilized at the threshold; or,
ƒ has not touched down in the landing zone; or,
ƒ has an adverse or an unintended hazardous touchdown
event shall
ƒ Execute an immediate go-around.
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Stabilized Landings - Charbonneau CASS 2010
Bracketing and Tolerances
ƒ It should be anticipated that variations may be present due to
environmental conditions, pilot performance or other
unexpected conditions
ƒ Pilots must consider the effects of deviations as they relate to
the increase in landing distance
ƒ Prior to touchdown, pilots should never continue the landing
should they assess that they will not have sufficient runway
available, including reasonable safety margins to account for
unexpected conditions – immediately go-around
ƒ If a pilot experiences an adverse or unintended hazardous
touchdown – immediately go-around
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While pilots should seek to achieve precise stabilized landing parameters when
transitioning to the landing phase at the 50 TCH, it should be anticipated that
variations may be present due to environmental conditions, pilot performance or other
unexpected conditions. When considering acceptable deviation tolerances, pilots must
consider the effects of deviations as they relate to the increase in landing distance as
previously described. Pilots should never continue the landing should they assess that
they will not have sufficient runway available, including reasonable safety margins to
account for unexpected conditions.
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Stabilized Landings - Charbonneau CASS 2010
Examples of
Bracketing and Tolerances
ƒ Target Airspeed = Vref to Vref + 5 knots
– At Vref + 5 to Vref + 10 knots – CAUTION –
increased speed condition exists – pilots should
touchdown in the landing zone without delay and
aggressively transition to the full braking
configuration (commensurate with the available
runway and runway conditions); and
– At Vref + 10 knots or greater – WARNING Excess
speed condition exists – requires immediate goaround
45
Note: The full braking configuration is meant to be commensurate with the
available runway and runway conditions and should be in accordance with the
planned and briefed braking performance. This planned and briefed braking
performance forms part of the braking strategy which also includes “what if”
conditional plans. In some cases, when runway distances are limited, this may
mean maximum braking effort.
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Stabilized Landings - Charbonneau CASS 2010
Examples of
Bracketing and Tolerances
ƒ Target Threshold Crossing Height = 50 – 80 feet
– At TCH 80 - 100 feet – CAUTION – increased
landing distance condition exists – pilots should
touchdown in the landing zone without delay and
aggressively transition to the full braking
configuration (commensurate with the available
runway and runway conditions); and
– At Threshold Crossing Height 100 feet or greater WARNING Excess altitude condition exists –
46
requires immediate go-around
Note: The full braking configuration is meant to be commensurate with the
available runway and runway conditions and should be in accordance with the
planned and briefed braking performance. This planned and briefed braking
performance forms part of the braking strategy which also includes “what if”
conditional plans. In some cases, when runway distances are limited, this may
mean maximum braking effort.
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Stabilized Landings - Charbonneau CASS 2010
Examples of
Bracketing and Tolerances
ƒ Target Landing Zone – 1000 – 1500 feet from the
threshold
– At 1500 – 2500 feet from threshold, or approaching
the end of the first third of the runway - CAUTION –
increased landing distance condition exists – pilots
shall touchdown immediately and aggressively
transition to the full braking configuration
(commensurate with the available runway and
runway conditions); and
– At 2500 feet or greater from the threshold, or at the
end of the first third of the runway - WARNING
Excess landing distance condition exists –
requires immediate go-around
47
Note: The full braking configuration is meant to be commensurate with the
available runway and runway conditions and should be in accordance with the
planned and briefed braking performance. This planned and briefed braking
performance forms part of the braking strategy which also includes “what if”
conditional plans. In some cases, when runway distances are limited, this may
mean maximum braking effort.
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Stabilized Landings - Charbonneau CASS 2010
Outline
ƒ Consider the Flight Safety Foundation data for Runway
Excursions
ƒ Understand landing certification concepts
ƒ Look into threats to safe landings
ƒ Define Stabilized Landing Concept and identify Criteria
ƒ Demonstrate how C-FOQA can reveal
opportunities to improve
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Stabilized landing criteria are derived from guidelines established by the FAA,
manufacturer’s performance certification data, safety research, and empirical data
gathered from review of Corporate Flight Operations Quality Assurance (hereafter CFOQA) reports. It considers the effects of excessive height, airspeed, groundspeed,
landing beyond the touchdown zone, and insufficient or ineffective braking. Each of
the criteria will need to be met, within reasonable tolerances, in order for a landing to
be considered as stabilized. Once the concept of stabilized landings is defined, this
presentation serves to reinforce the benefits of monitoring both stabilized approaches
and landings using a flight operations quality assurance program, such as C-FOQA.
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Stabilized Landings - Charbonneau CASS 2010
Stabilized Landing Monitoring
ƒ The C-FOQA program has been in effect since early
2006 and has monitored in excess of twelve thousand
flights
ƒ The following slides have been published by Austin
Digital, and may contain proprietary information
protected by patent.
ƒ FSF has approved the use of these slides to
demonstrate the capabilities of the C-FOQA program
when considering the stabilized landing criteria
ƒ The distributions depicted represent the best
estimate for accuracy
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The program capabilities have been widely publicized and include monitoring of
approach conditions, aircraft limitations and flight operations
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Stabilized Landings - Charbonneau CASS 2010
C‐FOQA Annual Unstable Approach Event Rates
*Error Bars Calculated with 90% confidence interval
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
50
The unstable approach event rate decline has been remarkable and demonstrates
the potential for the C-FOQA program to bring awareness to the landing
environment as well. Given the awareness, pilots seek to achieve more precise
flight parameters.
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Stabilized Landings - Charbonneau CASS 2010
Percent of Unstable Approaches that end in a
Go-Around
*Error Bars Calculated with 90% confidence interval
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
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Stabilized Landings - Charbonneau CASS 2010
Unstabilized Approaches
and Initiation of Go-Arounds
19%
20%
Unstabilized
approaches
Go‐around not
conducted when
warranted
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The coding scheme developed for data analysis in the original (1999) approach and
landing accident (ALA) study — and adapted for the 2009 study — did not provide
for explicitly counting accidents that involved unstabilized approaches. Similarly,
there was no causal factor citation for failure to initiate a go-around. The data shown
in this slide are lower-bound estimates (i.e., these are the minimums) for the 1,007
accidents that occurred in 1995 through 2007. These data were compiled by
evaluating two subsets of ALAs: runway excursions and undershoots. It is likely that
the values for the entire ALA data set are somewhat higher.
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Stabilized Landings - Charbonneau CASS 2010
C‐FOQA Seasonal Unstable Approach Event Rates (All Years)
*Error Bars Calculated with 90% confidence interval
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
53
Q3 event rates are higher.
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Stabilized Landings - Charbonneau CASS 2010
Stabilized Landing Distribution Examples
ƒ Speed at Threshold
ƒ Height at Threshold
ƒ Tailwind on Landing
ƒ Landing in the Touchdown Zone
ƒ Runway remaining with 80 knots
ƒ Comparison of events following unstabilized approaches
versus stabilized approaches
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The development of stabilized landing criteria and monitoring of event rates will serve
to bring awareness to aircraft performance of the landing phase; including, both the
airborne and ground landing distance.
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Stabilized Landings - Charbonneau CASS 2010
Speed at Threshold
Vref – Vref + 5
Caution Limit
Warning Limit
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
55
Vref + 5-10 is the highest distribution.
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Stabilized Landings - Charbonneau CASS 2010
Threshold Crossing Heights
TCH 50 ft
Caution Limit
Warning Limit
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
56
While runway excursion does not include short landings – this slide indicates that the
hazard is real.
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Stabilized Landings - Charbonneau CASS 2010
Threshold Crossing Heights
TCH 50 ft
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
57
Another depiction using different bin sizes – presented to demonstrate that C-FOQA is
versatile.
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Stabilized Landings - Charbonneau CASS 2010
Tailwind on Landing
Tailwinds - Headwinds
Caution Limit
Warning Limit
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
58
Indicates a low incidence of high tailwind landings
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Stabilized Landings - Charbonneau CASS 2010
Tailwind on Landing
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
59
Scatter chart showing a clear depiction of incidence of tailwinds.
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Stabilized Landings - Charbonneau CASS 2010
Landing in the Touchdown Zone
1000-1500 feet
Caution Limit
2500 +
Warning Limit
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
60
Clearly depicts the average is 1500-2000 – there is a high incidence of long landings
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Stabilized Landings - Charbonneau CASS 2010
Landing in the Touchdown Zone
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
61
Above is a depiction of the best estimate of the distance from threshold of the first
touchdown, grouped by landings on various runway lengths. It is interesting to note
that when faced with runways of 6000 feet or less, pilots can consistently achieve
touchdowns in the 1500 foot range; however, as the runway length increases as do
the touchdown distances.
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Stabilized Landings - Charbonneau CASS 2010
Runway Remaining at 80 Knots
2000 feet
Caution Limit
Warning Limit
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
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Stabilized Landings - Charbonneau CASS 2010
Runway Remaining at 80 Knots
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
63
The chart above is the best estimate of runway remaining when slowed to 80 knots,
grouped by landings on various runway lengths.
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Stabilized Landings - Charbonneau CASS 2010
Unstabilized vs. Stabilized
The Common Culprit
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
This slide is published by Austin Digital, Inc and may contain proprietary information protected by patent.
64
When stabilized landing criteria are used in conjunction with stabilized approach
criteria, it will be possible to assess if the decision to continue an unstabilized
approach resulted in an unstabilized landing. This should serve to be a strong
indicator of the overall risk of the approach and landing.
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Stabilized Landings - Charbonneau CASS 2010
Recommendations - Operators
ƒ Operators should develop, publish, train and monitor
stabilized landing criteria
ƒ Operators should provide pilots with quick and easy
cockpit access to aircraft performance data pertinent for
both anticipated and unanticipated landing and runway
conditions
ƒ Operators should manage the risks associated with
runway excursions in their operations by implementing a
FOQA program. This program should include performance
measurements for: height, airspeed and tailwind at
threshold crossing, touchdown point, and landing roll
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Stabilized Landings - Charbonneau CASS 2010
Recommendations - Pilots
ƒ Pilots should reaffirm their commitment to adhere to
stabilized approach criteria and go-around should
approaches become unstabilized below 1000 feet IMC or
500 feet VMC
ƒ Pilots should plan and brief a stabilized landing strategy
and go-around should landings be assessed as
unstabilized at the threshold, or become unstabilized
ƒ Pilots should incorporate the runway excursion risk
awareness tool into their flight risk awareness program
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Stabilized Landings - Charbonneau CASS 2010
Recommendations - All
ƒ Must read!!!!
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Stabilized Landings - Charbonneau CASS 2010
Recommendations - Other
ƒ The FSF should endorse and promote the concept of
stabilized landing criteria
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Stabilized Landings - Charbonneau CASS 2010
Summary – Stabilized Landings
9A landing is stabilized when the aircraft is positively
controlled from a point 50 feet above the threshold to
a full stop on the landing surface, without any
unintended or adverse aircraft deviations from the
planned and briefed maneuver.
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Stabilized Landings - Charbonneau CASS 2010
Summary - Criteria
9Assess, plan and brief a landing strategy
9Achieve threshold parameters for height and speed
9Touchdown firmly in the landing zone
9Brake effectively to stop safely
9And finally……..
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Stabilized Landings - Charbonneau CASS 2010
Know when to Go-Around
9A landing that is not stabilized at the threshold; or,
9 has not touched down in the landing zone; or,
9has an adverse or an unintended hazardous
touchdown event
9Shall execute an immediate go-around.
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Stabilized Landings - Charbonneau CASS 2010
Acknowledgements
ƒ Mr. Jim Burin – Flight Safety Foundation
– Leading the charge on Runway Excursions
ƒ Mr. Ted Mendenhall – Flight Safety Foundation
– Painstaking efforts to promote and develop C-FOQA
ƒ Mr. Andy Rector – Austin Digital
– Providing excellent technical analysis
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Stabilized Landings - Charbonneau CASS 2010
End
Steve.Charbonneau@Altria.com
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