approach techniques

8/22/2019 Approach Techniques

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Approach Techniques

Flying Stabilized ApproachesFlight Operations Briefing Notes

Flight Operations Briefing Notes

Approach Techniques

Flying Stabilized Approaches

I Introduction

Rushed and unstabilized approaches are the largest contributory factor in CFIT andother approach-and-landing accidents.

Rushed approaches result in insufficient time for the flight crew to correctly:

Plan;

Prepare; and,

Execute a safe approach.

This Flight Operations Briefing Note provides an overview and discussion of:

Criteria defining a stabilized approach; and,

Factors involved in rushed and unstabilized approaches.

Note:

Flying stabilized approaches complying with the stabilization criteria and approach

gates defined hereafter, does not preclude flying a Delayed Flaps Approach (also called

a Decelerated Approach) as dictated by ATC requirements.

II Statistical Data

(Source: Flight Safety Foundation Flight Safety Digest Volume 17 & 18 November 1998 / February 1999).

Continuing an unstabilized approach is a causal factor in 40 % of all approach-and-landing accidents.

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In 75% of the off-runway touchdown, tail strike or runway excursion/overrun accidents,

the major cause was an unstable approach.

Table 1 shows the factors involved in rushed and unstabilized approaches.

Factor % of Events

High and/or fast approach

or

Low and/or slow approach

66 %

Flight-handling difficulties :

- Demanding ATC clearances

- Adverse wind conditions

45 %

Table 1

Factors Involved in Unstabilized Approaches

III Stabilization Heights

The following minimum stabilization heights are recommended to achieve timely

stabilized approaches:

Meteorological Conditions Height above Airfield Elevation

IMC 1000 ft

VMC 500 ft

Table 2

Minimum Stabilization Heights

N o t e :

A lower minimum stabilization height may be allowed for circling approaches(e.g. 400 ft).

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IV Defining the Elements of a Stabilized Approach

An approach is considered stabilized only if all the following elements are achieved

before or when reaching the applicable stabilization height:

The aircraft is on the correct lateral and vertical flight path

(based on navaids guidance or visual references)

Only small changes in heading and pitch are required to maintain this flight path

The aircraft is in the desired landing configuration

The thrust is stabilized, usually above idle, to maintain the target approach speed along

the desired final approach path

The landing checklist has been accomplished as well as any required specific briefing

No flight parameter exceeds the criteria defined inTable 4

Table 3

The Elements of a Stabilized Approach All Approaches

N o t e 1 :

For Non-Precision Approaches, some of these elements (desired landing configurationand VAPP) should be achieved when the aircraft reaches the FAF (Airbus recommended

technique).

N o t e 2 :

Non-normal conditions requiring deviation from the above elements of a stabilized

approach should be briefed formally.

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V Excessive Flight Parameter Deviation Callouts Criteria

When reaching the applicable stabilization height and below, a callout should be

performed by the PNF if any flight parameter exceeds the limits provided in Table 4.

Parameter Callout Criteria

Airspeed Lower than V APP 5 kt or Greater than V APP + 10 kt (*)

Vertical Speed Greater than 1000 ft/mn

Pitch Attitude Lower than (**) Nose Down or Greater than (**) Nose Up

Bank Angle Greater than 7 degrees

LOC deviation 1/4 dot or Excessive (Beam) Deviation Warning

Glide Slope deviation

(ILS)1 dot or Excessive (Beam) Deviation Warning

Table 4

Excessive Flight-Parameter-Deviation Callouts

(*)The final approach speed VAPP is considered to be equal to VREF+ 5 kt (or VLS + 5 kt,

as applicable).

V REF is the reference target threshold speed in the full flaps landing configuration(i.e., in the absence of airspeed corrections because of wind, windshear or non-normalconfiguration).

(**)Refer to the applicable SOPs for applicable pitch attitude limits.

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VI Benefits of a Stabilized Approach

Conducting a stabilized approach increases the flight crew overall situational

awareness: Horizontal situational awareness :

By closely monitoring the flight path;

Speed awareness :

By monitoring speed deviations;

Vertical situational awareness :

By monitoring the vertical flight path and the rate of descent;

Energy awareness :

By maintaining the engines thrust to the level required to fly a 3-degreeapproach path at the final approach speed (or at the minimum ground speed, asapplicable).

This also enhances the readiness for go-around.

In addition, a stabilized approach provides the following benefits:

More time and attention are available for the monitoring of ATC communications,weather conditions, systems operation;

More time is available for effective monitoring and back-up by the PNF;

Defined flight-parameter-deviation criteria and minimum stabilization height supportthe decision to land or go-around;

Landing performance is consistent with published performance; and,

Situational awareness is increased.

VII Best Practices

Throughout the entire flight a next target should be defined to stay ahead ofthe aircraft at all times.

The defined next target should be any required combination of:

A position;

An altitude;

A configuration;

A speed;

A vertical profile (vertical speed or flight path angle); and,

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A power setting (e.g. thrust is stabilized, usually above idle, to maintain the target

approach speed along the desired final approach path).

If it is anticipated that one or more element(s) of the next target will not be met,the required corrective action(s) should be taken without delay.

During the approach and landing, the successive next targets should constitute gatesthat should be met for the approach to be continued (Figure 1).

Figure 1

Typical Gates during Final Approach

The Final Approach Fix (FAF), the Outer Marker (OM) or an equivalent fix(as applicable) constitute an assessment gate to confirm the readiness to proceedfurther; this assessment should include the following:

1000 FT

500 FT

FAF

Visibility or RVR (and ceiling, as appropriate):

Better than or equal to applicable minimums;

Aircraft readiness:

Position, altitude, configuration and energy; and,

Crew readiness:

Briefing completed and agreement on approach conditions.

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The minimum stabilization height constitutes a particular gate along the final approach(e.g. for an ILS approach, the objective is to be stabilized on the final descent pathat VAPP in the landing configuration, at 1000 feet above airfield elevation in IMC, or

at 500 feet above airfield elevation in VMC, after continuous deceleration on the glideslope).

If the aircraft is not stabilized on the approach path in landing configuration,at the minimum stabilization height, a go-around must be initiated unless the crewestimates that only small corrections are necessary to rectify minor deviations fromstabilized conditions due, amongst others, to external perturbations.

Following a PNF flight parameter exceedance callout, the suitable PF response will be:

Acknowledge the PNF callout, for proper crew coordination purposes

Take immediate corrective action to control the exceeded parameter back into

the defined stabilized conditions

Assess whether stabilized conditions will be recovered early enough prior to landing,

otherwise initiate a go-around.

VIII Factors Involved in Unstabilized Approaches

The following circumstances, factors and errors are often cited when discussing rushedand unstabilized approaches:

Fatigue (e.g., due to disrupted sleep cycle, personal stress, );

Pressure of flight schedule (i.e., making up for takeoff delay, last leg of the day, );

Any crew-induced or controller-induced circumstances resulting in insufficient timeto plan, prepare and execute a safe approach;

This includes accepting requests from ATC for flying higher and/or faster thandesired or flying shorter routings than desired;

ATC instructions that result in flying too high and/or too fast during the initial orfinal approach (e.g., request for maintaining high speed down to the [outer] markeror for GS capture from above slam-dunk approach);

Excessive altitude and / or excessive airspeed (i.e., inadequate energymanagement) early in the approach;

Late runway change (i.e., lack of ATC awareness of the time required to reconfigure

the aircraft systems for a new approach);

Non-standard task-sharing resulting in excessive head-down work (e.g., FMSreprogramming);

Short outbound leg or short down-wind leg (e.g., in case of unidentified trafficin the area);

Inadequate use of automation: Late takeover from automation (e.g., in case of APfailing to capture the GS, usually due to crew failure to arm the approach mode);

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Premature or late descent due to absence of positive FAF identification;

Insufficient awareness of wind conditions:

Tailwind component;

Low altitude wind shear;

Local wind gradient and turbulence (e.g., caused by terrain, forest or buildings);or,

Recent weather along the final approach path (e.g., downdraft caused bya descending cold air mass following a rain shower);

Incorrect anticipation of aircraft deceleration characteristics in level flight or ona 3-degree glideslope;

Failure to recognize deviations or to remember the excessive-parameter-deviationcriteria;

Belief that the aircraft will be stabilized at the stabilization height or shortly

thereafter;

Excessive confidence by the PNF that the PF will achieve a timely stabilization;

PF/PNF over reliance on each other to call excessive deviations or to call fora go-around;

Visual illusions during the visual segment;

Continued approach without acquisition of adequate visual references or after lossof visual references;

Failure to accurately follow the PAPI / VASI; and / or,

Failure to adequately maintain the aiming point (i.e., duck-under).

IX Typical Deviations Observed in Unstabilized Approaches

The following procedure deviations or flight path excursions often are observed, aloneor in combination, in rushed and unstabilized approaches (figures provided between

brackets reflect extreme deviations observed in actual unstabilized approaches,worldwide):

Full approach flown at idle down to touchdown, because of excessive airspeedand/or altitude early in the approach;

Steep approach (i.e., above desired flight path with excessive vertical speed up to 2200 ft/mn, flight path angle up to 15 % gradient / 9-degree slope);

Steep approaches appear to be twice as frequent as shallow approaches;

Shallow approach (i.e., below desired glide path);

Low airspeed maneuvering (i.e., inadequate energy management);

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Excessive bank angle when capturing the final approach course (up to 40-degree);

Activation of a GPWS warning:

Mode 1 : SINK RATE;

Mode 2A : TERRAIN (not full flaps);

Mode 2B : TERRAIN (full flaps).

Late extension of flaps or flaps load relief system activation (as applicable),resulting in the late effective extension of flaps;

Flight-parameter excessive deviation when crossing the stabilization height:

Excessive airspeed (up to V REF + 70 kt);

Not aligned (up to 20-degree heading difference);

Excessive bank angle (up to 40 -degrees); Excessive vertical speed (up to 2000 ft/mn);

Excessive glide slope deviation (up to 2 dots);

Excessive bank angle, excessive sink rate or excessive maneuvering whileperforming a side-step;

Speedbrakes being still extended when in short final (i.e., below 1000 ft aboveairfield elevation);

Excessive flight-parameter deviation(s) down to runway threshold;

High runway-threshold crossing (up to 220 ft);

Long flare and extended touchdown.

X Companys Prevention Strategies and Personal Lines-of-defense

Companys prevention strategies and personal lines-of-defense to reduce the number ofunstabilized approaches should:

Identify and minimize the factors involved; and,

Provide recommendations for the early detection and correction of unstabilized

approaches.

The following four-step strategy is proposed:

Anticipate;

Detect;

Correct; and,

Decide.

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X.1 Anticipate

Some factors likely to result in a rushed and unstabilized approach can be anticipated.

Whenever practical, flight crews and controllers should avoid situations that may resultin rushed approaches.

The descent-and-approach briefing provides an opportunity to identify and discussfactors such as :

Non-standard altitude or speed restrictions requiring a careful energy management:

An agreed strategy should be defined for the management of the descent,deceleration and stabilization (i.e., following the concepts of next targets andapproach gate);

This strategy will constitute a common objective and reference for the PF andPNF.

X.2 Detect

Defined excessive-parameter-deviation criteria and a defined stabilization heightprovide the PF and PNF with a common reference for effective:

Monitoring (i.e., early detection of deviations); and,

Back-up (i.e., timely and precise deviation callouts for effective corrections).

To provide the time availability and attention required for an effective monitoring andback-up, the following should be avoided:

Late briefings;

Unnecessary radio calls (e.g., company calls);

Unnecessary actions (e.g., use of ACARS); and,

Non-pertinent intra-cockpit conversations (i.e., breaking the sterile-cockpit rule).

Reducing the workload and cockpit distractions and/or interruptions also providesthe flight crew with more alertness and availability to:

Cope with fatigue;

Comply with an unanticipated ATC request (e.g., runway change or visual

approach);

Adapt to changing weather conditions or approach hazards; and,

Manage a system malfunction (e.g., flaps jamming or gear failing to extend or todownlock).

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X.3 Correct

Positive corrective actions should be taken before deviations develop into a challenging

or a hazardous situation in which the only safe action is a go-around.

Corrective actions may include:

The timely use of speed brakes or the early extension of landing gear to correctan excessive altitude or an excessive airspeed;

Extending the outbound leg or downwind leg.

X.4 Decide

If the aircraft is not stabilized on the approach path in landing configuration,at the minimum stabilization height, a go-around must be initiated unless the crew

estimates that only small corrections are necessary to rectify minor deviations fromstabilized conditions due, amongst others, to external perturbations.

Following a PNF flight parameter exceedance callout, the suitable PF response will be:

Acknowledge the PNF callout, for proper crew coordination purposes

Take immediate corrective action to control the exceeded parameter back into thedefined stabilized conditions

Assess whether stabilized conditions will be recovered early enough prior to landing,otherwise initiate a go-around.

The following behaviors often are involved in the continuation of an unstabilizedapproach:

Confidence in a quick recovery (i.e., postponing the go-around decision whenparameters are converging toward target values);

Overconfidence because of a long and dry runway and/or a low gross-weight,although airspeed and/or vertical speed are excessive;

Inadequate readiness or lack of commitment to conduct a go-around;

A change of mindset should take place from:

We will land unless ; to,

Lets be prepared for a go-around and we will land if the approach is stabilizedand if we have sufficient visual references to make a safe approach andlanding.

Go-around envisaged but not initiated because the approach was considered beingcompatible with a safe landing; and,

Absence of decision due to fatigue or workload (i.e., failure to rememberthe applicable excessive deviation criteria).

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XI Summary of Key Points

Three essential parameters need to be stabilized for a safe approach:

Aircraft track;

Flight path angle; and,

Airspeed.

Depending on the type of approach and aircraft equipment, the most appropriate levelof automation and visual cues should be used to achieve and monitor the stabilizationof the aircraft.

When breaking-out of the cloud overcast and transitioning to visual references,the pilots perception of the runway and outside environment should be kept constant

by maintaining:

Drift correction:

To continue tracking the runway centerline, resisting the tendency toprematurely align the aircraft with the runway centerline;

Aiming point (i.e., the touchdown zone):

To remain on the correct flight path until flare height, resisting the tendency to

move the aiming point closer and, thus, descend below the desired glide path(i.e., duck-under); and,

Final approach speed and ground speed:

To maintain the energy level.

XII Associated Flight Operations Briefing Notes

The following Flight Operations Briefing Notes can be reviewed in association withthe above information:

Descent and Approach Profi le Management

Energy Management during Approach

Being Prepared to Go-around

Flying Constant-Angle Non-Precision Approaches

The Final Approach Speed

Factors Affecting Landing Distances

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XIII Regulatory references

ICAO Annex 6 Operations of Aircraft, Part I International Commercial Air

transport Aeroplanes, Appendix 2, 2.1.25

ICAO Procedures for Air navigation services Aircraft Operations (PANS-OPS, Doc8168), Volume I Flight Procedures (particularly, Part IX - Chapter 1 - StabilizedApproach Parameters, Elements of a Stabilized Approach and Go-around Policy)

XIV Airbus References

Flight Crew Operating Manuals (FCOM) Standard Operating Procedures

A318/A319/A320/A321 & A330/A340 Flight Crew Training Manuals (FCTM) Approach General Trajectory Stabilization

XV Additional Reading Materials

U.S. National Transportation Safety Board (NTSB) Report NTSB-AAS-76-5

Special Study: Flight Crew Coordination Procedure in Air Carrier Instrument LandingSystem Approach Accidents

This FOBN is part of a set of Flight Operations Briefing Notes that provide an overview of the applicable standards,flying techniques and best practices, operational and human factors, suggested company prevention strategies and personal

lines-of-defense related to major threats and hazards to flight operations safety.

This FOBN is intended to enhance the reader's flight safety awareness but it shall not supersede the applicable regulations

and the Airbus or airline's operational documentation; should any deviation appear between this FOBN and the Airbus orairlines AFM / (M)MEL / FCOM / QRH / FCTM, the latter shall prevail at all times.

In the interest of aviation safety, this FOBN may be reproduced in whole or in part - in all media - or translated; any use ofthis FOBN shall not modify its contents or alter an excerpt from its original context. Any commercial use is strictly excluded.

All uses shall credit Airbus.

Airbus shall have no liability or responsibility for the use of this FOBN, the correctness of the duplication, adaptation ortranslation and for the updating and revision of any duplicated version.

Airbus Customer Services

Flight Operations Support and Services

1 Rond Point Maurice Bellonte - 31707 BLAGNAC CEDEX FRANCE

FOBN Reference : FLT_OPS APPR SEQ 01 REV 02 OCT. 2006

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Aircraft Energy Management during ApproachFlight Operations Briefing Notes

Flight Operations Briefing Notes

Approach Techniques

Aircraft Energy Management during Approach

I

Introduction

Inability to assess or manage the aircraft energy level during the approach often iscited as a causal factor in unstabilized approaches.

Either a deficit of energy (being low and/or slow) or an excess of energy (being highand/or fast) may result in approach-and-landing accidents, such as:

Loss of control;

Landing short;

Hard landing;

Tail strike;

Runway excursion; and/or,

Runway overrun.

This Flight Operations Briefing Note provides background information and operational

guidelines for a better understanding of:

Energy management during intermediate approach:

How fast can you fly down to the FAF or outer marker?

Energy management during final approach:

Hazards associated with flying on the backside of the power curve (as defined by

Figure 2).

Refer also to the Flight Operations Briefing Note Factors Affecting the FinalApproach Speed (VAPP).

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II

III

IV

Statistical Data

Approximately 70 % of rushed and unstable approaches involve an incorrectmanagement of the aircraft energy level, resulting in an excess or deficit of energy, asfollows:

Being slow and/or low on approach : 40 % of events;

Being fast and/or high on approach: 30 % of events.

Aircraft Energy Level

The level of energy of an aircraft is a function of the following primary flight parametersand of their rate of change (trend):

Airspeed and speed trend;

Altitude and vertical speed (or flight path angle);Aircraft configuration (i.e., drag caused by speed brakes, slats/flaps and/or landinggear); and,

Thrust level.

One of the tasks of the pilot is to control and monitor the energy level of the aircraft(using all available cues) in order to:

Maintain the aircraft at the appropriate energy level throughout the flight phase:

Keep flight path, speed, thrust and configuration; or,

Recover the aircraft from a low energy or high energy situation, i.e., from:Being too slow and/or too low; or,

Being too fast and/or too high.

Controlling the aircraft energy level consists in continuously controlling eachparameter: airspeed, thrust, configuration and flight path, and in transiently tradingone parameter for another.

Autopilot and flight director modes, aircraft instruments, warnings and protections aredesigned to assist the flight crew in these tasks.

Going Down and Slowing Down :How Fast Can you Fly Down to the Marker?

A study by the U.S. NTSB acknowledges that maintaining a high airspeed down tothe outer marker (OM) does not favor the capture of the glideslope beam by theautopilot or the aircraft stabilization at the defined stabilization height.

The study concludes that no speed restriction should be imposed when within 3 nm to4 nm before the OM, mainly in instrument meteorological conditions (IMC).

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Nevertheless, ATC requests for maintaining a high airspeed down to the marker (160 kt

to 200 kt IAS typically) are frequent at high-density airports, to increase the aircraftlanding rate.

The purpose of the following part is to:

IV.1

Recall the definition of stabilization heights;

Illustrate the aircraft deceleration characteristics in level flight and on a 3-degreeglide path;

Provide guidelines for assessment of the maximum speed which, reasonably, can bemaintained down to the marker, as a function of:

The distance from the OM to the runway threshold; and,

The desired stabilization height.

Stabilization Height

The definition and criteria for a stabilized approach are provided in the FlightOperations Briefing NoteFlying Stabilized Approaches.

The minimum stabilization height must be:

IV.2

1000 ft above airfield elevation in IMC;

500 ft above airfield elevation in VMC.

Aircraft Deceleration Characteristics

Although deceleration characteristics largely depends on the aircraft type and gross-

weight, the following typical values can be considered for a quick assessment andmanagement of the aircraft deceleration capability:

Deceleration in level flight:

With approach flaps extended: 10 to 15 kt-per-nm;

With landing gear down and flaps full: 20 to 30 kt-per-nm;

Deceleration on a 3 degree glide path:

With landing flaps and gear down: 10 to 20 kt per nm.

Note:

A 3 degree glide path is typically equivalent to a descent-gradient of300 ft-per-nm or a700 ft/mn vertical speed, for a final approach ground speed of140 kt.

Decelerating on a 3 degree glide path in clean configuration usually is not possible.

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1000 ft

OM

500 ft

2000 ft

V APP = 130 kt V MAX at OM = 160 kt

6.03.0 nm0

Deceleration

Segment( 10 kt/nm )

MM

1000 ft

OM

500 ft

2000 ft

V APP = 130 kt V MAX at OM = 160 kt

6.03.0 nm0

Deceleration

Segment( 10 kt/nm )

MM

Approach Techniques


When established on a typical 3 degree glide slope path with only slats extended

(i.e., with no flaps), it takes approximately 3 nm (1000 ft) to decelerate down to thetarget final approach speed and to establish the landing configuration.

Speedbrakes may be used to achieve a faster deceleration, as allowed by the aircrafttype (i.e. speedbrakes inhibition).

Usually the use of speedbrakes is not recommended when below 1000 ft above airfieldelevation and/or in the landing flaps configuration.

Typically, slats should be extended not later than 3 nm before the FAF.

Figure 1 illustrates the aircraft deceleration capability and the maximum possiblespeed at the OM, based on a conservative deceleration rate of 10 kt per nm on a 3

degree glide path.

The following conditions are considered:

IMC (stabilization height 1000 ft above airfield elevation); and,

Final approach speed (VAPP) = 130 kt.

The maximum deceleration achievable between the OM (typically 6.0 nm from therunway threshold) and the stabilization point (1000 ft above airfield elevation / 3.0 nm)is: 10 kt-per-nm x (6.0 3. 0) nm = 30 kt.

In order to be stabilized at 130 kt at 1000 above airfield elevation, the maximum speed

that can be accepted and maintained down to the OM is: 130 kt + 30 kt = 160 kt.

Figure 1

Deceleration along Glide Slope - Typical

Note: The OM may be located from 4 to 6 NM from the runway threshold.

Whenever being required to maintain a high speed down to the marker, the abovequick computation may be considered for assessing the feasibility of the ATC request.


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V

V.1

Avoiding the Back Side of the Power Curve

During an unstable approach, the airspeed or the thrust setting often is observed todeviate from the target values:

Airspeed is below the target final approach speed (VAPP); and/or,

Thrust is reduced and maintained at idle.

Thrust-required-to-fly Curve

Figure 2 illustrates the thrust-required-to-fly curve (i.e. thepower curve).

Thrust Required to Fly

3-degree glide slope - Landing configuration

90 100 110 120 130 140 150 160 170 180 190 200

Airspeed ( kt )

Requiredthrust

Vminimum thrust

Thrust for VAPP

Stable

UnstableUnstable

Given gross-weight

Given pressure altitude

Given flight path

Thrust Required to Fly

3-degree glide slope - Landing configuration

90 100 110 120 130 140 150 160 170 180 190 200

Airspeed ( kt )

Requiredthrust

Vminimum thrust

Thrust for VAPP

Stable

Given gross-weight

Given pressure altitude

Given flight path

Figure 2Power Curve Typical

The power curve is divided in two parts:

The left side of the power curve, called the backside of the power curve;

The right side of the power curve.

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The difference between the available-thrust and the thrust-required-to-fly(i.e., the thrust balance):

Represents the climb or acceleration capability (if the available-thrust exceeds

the required-thrust); or,

Indicates that speed and/or flight path cannot be maintained (if the required-thrustexceeds the available-thrust).

The right part of the power curve is the normal area of operation.

The thrust balance is such that, when the thrust is set to fly VAPP on the glideslope, anyincrease of the aircraft speed due to a perturbation is rapidly washed out, because ahigher thrust would be required to fly at this higher speed on the glideslope.

Conversely, when the thrust is set to fly VAPP on the glideslope, any speed loss due toa perturbation is rapidly washed out, because a lower thrust would be required to fly at

this lower speed on the glideslope.In other words, in case of perturbation, the aircraft speed tends to come back tothe speed stabilized with that thrust level. The right part of the curve is called thestable part.

On the backside of the power curve, the thrust balance is such that, at given thrustlevel, any tendency to decelerate increases the thrust-required-to-fly and, hence,

amplifies the tendency to decelerate.

Conversely, any tendency to accelerate decreases the thrust-required-to-fly and,hence, amplifies the tendency to accelerate.

The minimum thrust speed (V minimum thrust) usually is equal to 1.35 to 1.4 V stall, inlanding configuration.

The minimum final approach speed (i.e. VLS) is slightly in the backside of the power

curve.

Note: On Airbus aircraft, this part of the curve is rather flat.

If the airspeed drops below the final approach speed, more thrust is required to

maintain the desired flight path and/or to regain the target speed.

If the thrust is set at idle, approximately 5 seconds are necessary to obtain the enginethrust required to recover from a speed loss or to initiate a go-around (as illustrated in

Figure 3, Figure 4 and Figure 5).

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V.2

Engine Acceleration Characteristics

When flying the final approach segment with the thrust set and maintained at idle(approach idle), the pilot should be aware of the acceleration characteristics of jetengines, as illustrated below.

Thrust Response from Idle to GA Thrust

( typical engine-to-engine scatter )

0

20

40

60

80

100

0 1 2 3 4 5 6 7 8 9

Time ( seconds )

Thrust(in%G

Athr

ust)

Approach idle

10

Thrust Response from Idle to GA Thrust

( typical engine-to-engine scatter )

0

20

40

60

80

100

0 1 2 3 4 5 6 7 8 9

Time ( seconds )

Thrust(in%G

Athr

ust)

Approach idle

10

Figure 3

Engine Response Scatter- Typical

The acceleration capability of high by pass ratio jet engine is dictated by its physicalcharacteristics and controlled to:

Protect the engine against a stall or flameout;

Comply with the engine and aircraft certification requirements (U.S. FAR Part 33and FAR Part 25, respectively, or the applicable equivalent regulation).

The engine certification (FAR Part 33) ensures a time of 5 seconds or less toaccelerate from 15 % to 95 % of the go-around thrust.

The aircraft certification (FAR Part 25) ensures that the thrust achieved after8 seconds from power application (starting from flight/approach idle) allows a minimumclimb gradient of 3.2 % for go-around.

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Thrust Response - Approach Idle to GA

( aircraft certification requirements )

0

20

40

60

80

100

0 1 2 3 4 5 6 7 8 9

Time ( seconds )

Thrust(in%o

fGAthrust)

10

8 seconds (FAR 25)

Thrust Response - Approach Idle to GA

( aircraft certification requirements )

0

20

40

60

80

100

0 1 2 3 4 5 6 7 8 9

Time ( seconds )

Thrust(in%o

fGAthrust)

10

8 seconds (FAR 25)

Figure 4

Certified Thrust Response Typical

V.3 Go-around from Low Speed / Low Thrust

Table 1 indicates the thrust required (in % of the TOGA thrust) in order to achievethe following maneuvers:

Maneuvers % of TOGA Thrust

Flying a stabilized approach

(3-degree glide path / VAPP)

20 %

Arresting altitude loss and achieving level flight 30 %

Achieving Positive Climb > 30 %

Table 1

Thrust Required during GA Initiation

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Figure 5 illustrates the go-around trajectories associated with flying an approach with:

Speed on the target final approach speed (VAPP) with idle thrust;

Speed below VAPP (VAPP 10 kt) with idle thrust.

In case of go-around, the initial altitude loss and the time required for recoveringthe initial altitude are increased if airspeed is lower than the final approach speedand/or if thrust is set at idle. In particular, the effect of lack of thrust (i.e. thrust atidle) is significant in terms of altitude loss.

AltitudeLoss

Altitude Loss in Go-around

( Landing Configuration )

-50

-40

-30

-20

-10

0

10

20

30

0 1 2 3 4 5 6 7

Time ( seconds )

(infeetfromg

o-aroundinitiation)

8

V APP / Stabilized thrust

V APP / Idle

AltitudeLoss

Altitude Loss in Go-around

( Landing Configuration )

-50

-40

-30

-20

-10

0

10

20

30

0 1 2 3 4 5 6 7

Time ( seconds )

(infeetfromg

o-aroundinitiation)

8

V APP / Stabilized thrust

V APP / Idle

V APP - 10 kt / IdleV APP - 10 kt / Idle

Figure 5

Effect of Initial Speed and Thrust on Altitude Loss during Go-around (Typical)

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Approach Techniques


VI

VII

Summary of Key Points

A deceleration below the final approach speed should be accepted only in the following

cases:

GPWS terrain avoidance maneuver;

Collision avoidance maneuver; and,

Windshear procedure.

Nevertheless, in all three cases, the throttles/thrust levers must be advanced tothe maximum thrust (i.e., TOGA thrust) while initiating the maneuver.

Associated Flight Operations Briefing Notes

The following Flight Operations Briefing Notes should be reviewed along with the aboveinformation for a complete overview of the approach management:

Being Prepared for Go-around

Flying Stabilized Approaches

Flying Constant-angle Non-precision Approaches

Factors affecting the Final Approach Speed (VAPP)

VIII

IX

Regulatory References

ICAO Annex 6 Operation of Aircraft, Part I International Commercial AirTransport Aeroplanes, Appendix 2, 5.18, 5.19.

ICAO Procedures for Air navigation Services Aircraft Operations (PANS-OPS,Doc 8168), Volume I Flight Procedures.

Other References

U.S. National Transportation Safety Board (NTSB) Report NTSB-AAS-76-5 Special Study: Flight Crew Coordination Procedure in Air Carrier Instrument LandingSystem Approach Accidents.

Page 10 of 11
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Page 11 of 11

Approach Techniques


This Flight Operations Briefing Note (FOBN) has been adapted from the corresponding ALAR Briefing Note developed by

Airbus in the frame of the Approach-and-Landing Accident Reduction (ALAR) international task force led by the Flight Safety

Foundation.

This FOBN is part of a set of Flight Operations Briefing Notes that provide an overview of the applicable standards,flying techniques and best practices, operational and human factors, suggested company prevention strategies and personallines-of-defense related to major threats and hazards to flight operations safety.

This FOBN is intended to enhance the reader's flight safety awareness but it shall not supersede the applicable regulations

and the Airbus or airline's operational documentation; should any deviation appear between this FOBN and the Airbus orairlines AFM / (M)MEL / FCOM / QRH / FCTM, the latter shall prevail at all times.

In the interest of aviation safety, this FOBN may be reproduced in whole or in part - in all media - or translated; any use of

this FOBN shall not modify its contents or alter an excerpt from its original context. Any commercial use is strictly excluded.All uses shall credit Airbus and the Flight Safety Foundation.

Airbus shall have no liability or responsibility for the use of this FOBN, the correctness of the duplication, adaptation ortranslation and for the updating and revision of any duplicated version.

Airbus Customer Services

Flight Operations Support and Services

1 Rond Point Maurice Bellonte - 31707 BLAGNAC CEDEX France

FOBN Reference : FLT_OPS APPR SEQ03 REV02 OCT. 2005

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