4. initial climb

4. INITIAL CLIMB4. INITIAL CLIMB

Performance JAR 25Performance JAR 25

INITIAL CLIMBINITIAL CLIMB

Introduction

Climb segments

Climb requirements

Obstacle clearance

Departure sector

Reference zero

Flap configuration

Level-off height

Flexible takeoff

Extended second segment

Noise abatement procedures

INTRODUCTIONINTRODUCTION

To ensure obstacle clearance on initial climb with one engine out, the takeoff path must meet some requirements. This path starts at 35 ft and ends at least at 1500 ft, and has been divided into 4 segments.

Every segment has its own required configuration and climb gradient.

CLIMB SEGMENTSCLIMB SEGMENTS

1st SEGMENT

• TAKE OFF THRUST SET

• TAKE OFF FLAP

• GEAR DOWN

• V2 SPEED

2nd SEGMENT


• TAKE OFF FLAP

• GEAR UP

• V2 SPEED

3rd SEGMENT

• FLAP RETRACTION ALTITUDE


• ACCELERATION TO ENROUTE CLIMB SPEED

4th SEGMENT

• CLEAN CONFIGURATION

• MCT

• ENROUTE CLIMB SPEED

GE

AR

UP

MIN

40

0 f

t

CL

B S

PE

ED

MIN

15

00

ft

35 ft

MAX 10’

CLIMB SEGMENTSCLIMB SEGMENTS

1st SEGMENT 2nd SEGMENT 3rd SEGMENT 4th SEGMENT

GEAR DOWN UP UP UP

FLAPS TAKEOFF TAKEOFF RETRACTING RETRACTED

THRUST TAKEOFF TAKEOFF TAKEOFF MCT

SPEED V2 V2 ACCELERATING VCLEAN

Aircraft configuration all along the takeoff path

CLIMB REQUIREMENTSCLIMB REQUIREMENTS

Climb requirements are different for each segment, and they depend on the number of engines of the aircraft:

1st SEGMENT 2nd SEGMENT 3rd SEGMENT 4th SEGMENT

2 ENGINES POSITIVE 2,4 % -------- 1,2 %

3 ENGINES 0,3 % 2,7 % -------- 1,5 %

4 ENGINES 0,5 % 3,0 % -------- 1,7 %

Ground effect considered

CLIMB REQUIREMENTSCLIMB REQUIREMENTS

Dash 8 with one engine out

OBSTACLE CLEARANCEOBSTACLE CLEARANCE

GROSS TAKEOFF PATH:

It is the actual path that the aircraft follows.

NET TAKEOFF PATH:

It is the path that results after subtracting a mandatory gradient from the gross takeoff path.

The gradient reduction applied to obtain the net path depends on the number of engines of the aircraft:

2 ENGINES: - 0,8 %

3 ENGINES: - 0,9 %

4 ENGINES: - 1,0 %


The obstacle clearance requirements establish that the margin between the net takeoff path and the obstacles within the departure sector must be 35 ft.

Distance

Alt

itu

de

35 ft

GROSS TAKEOFF PATH

NET TAKEOFF PATH


The prescribed reduction in climb gradient may be applied as an equivalent reduction in acceleration along that part of the takeoff flight path at which the airplane is accelerated in level flight.

Distance

Alt

itu

de

35 ft

GROSS TAKEOFF PATH

NET TAKEOFF PATH


35 ftGross path

Net path

To avoid an obstacle, you have different possibilities:

TOD ASD CLIMB GRADIENT

FLAPS ↓ increases increases increases

TOW ↓ decreases decreases increases

V1 ↑ decreases increases no change

V2 ↑ increases no change increases

DEPARTURE SECTORDEPARTURE SECTOR

The departure sector begins at the end of the TODA (or at the end of TOD if a turn starts before the end of TODA), with a width of 300 ft on each side of the runway. This width increases with an angle of 7,1º up to a maximum width of:

1000 ft (300 m) for departures under VMC

2000 ft (600 m) for departures under IMC

1000 ft VMC

2000 ft IMC

300 ft

300 ft

7,1º


If the departure requires a heading change of more than 15º, the width of the departure sector increases. SIDs shall not require a turn before reaching 150 ft AGL (2 & 3 engines) or 250 ft AGL (4 engines):

2000 ft (600 m) for departures under VMC

3000 ft (900 m) for departures under IMC

2000 ft VMC3000 ft IMC


Turns within the departure sector are usually restricted to 2nd and 4th segment. Maximum bank angle is 15º; if more bank angle is needed for the departure, the obstacle clearance shall not be less than 50 ft.

JAR regulations (JAR-OPS 1.495) prohibit turns below the height equivalent to half wing span or 50 ft, whichever is less.

Bank angles are also limited to 15º up to 400 ft and to 25º above 400 ft.

Half wingspan

150 ft AGL

400 ft AGL

Turns prohibited

No SID turns required

Bank limit 15º

Bank limit 25º



REFERENCE ZEROREFERENCE ZERO

The point on the ground at the end of the Takeoff Distance Required (TODR) is usually known as reference zero.

Therefore, reference zero is that point where the net path reaches the screen height of 35 ft (15 ft for a wet runway) and the V2 speed, assuming critical engine failure at V1.

FLAP CONFIGURATIONFLAP CONFIGURATION

Depending on the distance between the obstacles and the runway, different flap settings will be more convenient.

For a distant obstacle, a lower flap setting will increase obstacle clearance capability.

For an obstacle close to the runway, a higher flap setting will improve obstacle clearance.

FLAP 5º

FLAP 15º

LEVEL-OFF HEIGHTLEVEL-OFF HEIGHT

The 3rd segment is also known as level-off height. Its minimum value is 400 ft AGL, but some airlines establish a value of 700 – 1000 ft AGL, as well as a EFP (Engine Failure Procedure).

The level-off height will depend also on the Takeoff Thrust Time limitation, which is usually 5 minutes with all engines operating and 10 minutes with one engine inoperative.

The Go Around thrust time limits are the same as for TO thrust.

FLEXIBLE TAKEOFFFLEXIBLE TAKEOFF

When your actual takeoff weight is lower than the maximum takeoff weight, you can perform a takeoff with less than the maximum takeoff thrust, thus improving engine life and maintenance costs.

To manage this thrust reduction, we use the concept of assumed or flexible temperature: The maximum OAT which would make the takeoff possible with our ATOW.

The maximum allowed thrust reduction is 25%.


Weight Thrust

Flat rated thrust

OAT

EGT limit

TrefOAT

Available thrust

Max TOW

ATOW

Flex Temp

Max Tref

25% max

Needed thrust


ATOW = 60000 Kg / Wind calm

Use the configuration giving the highest FLEX TEMP. If both configurations give the same FLEX TEMP, use the one giving the lowest speeds:

CONFIG 2 : V1 – 135, VR – 135, V2 – 137

FLEX TEMP: 52 ºC

QNH and bleed corrections may be applied to PTOW and TFLEX.

EXTENDED SECOND SEGMENTEXTENDED SECOND SEGMENT

If we extend the second segment (which is usually the most limitative), our PTOW may be improved.

The 2nd segment may be extended indefinitely, until the maximum takeoff thrust time limit is reached. At that moment, the 3rd segment must be commenced with the engines set at MCT (Maximum Continuous Thrust).

Extended second segment

MCT

Time limit (10 min)

NOISE ABATEMENT PROCEDURESNOISE ABATEMENT PROCEDURES

PROCEDURE A: Latter part noise relief method.

1500 ft

3000 ft

Reduce to climb power / thrust

Climb at V2 + 10 to 20 kt

Accelerate smoothly to en-route climb speed, retracting flaps on schedule.

Takeoff thrust

V2 + 10 to 20 kt

NOISE ABATEMENT PROCEDURESNOISE ABATEMENT PROCEDURES

PROCEDURE B: First part noise relief method.

1000 ft

3000 ft

Accelerate to VZF + 10 kt

Climb at not greater than VZF + 20 kt

Retract flaps on schedule

Reduce to climb power / thrust

Accelerate smoothly to en-route climb speed

Takeoff thrust

V2 + 10 to 20 kt

Documents

4. initial climb