04 - Climb & Cruise Flashcards
Describe procedures, limitations and techniques.
How many degrees do the ailerons have in cruise to remain in neutral position?
[DSC/27/10/20 – F/CTL System Display]
In cruise, to optimize fuel consumption, the neutral position of the ailerons is 1° down.
Can the flight crew enter a cruise flight level above the REC MAX FL in the FMS ACTIVE/PERF page?
[FCTM/PR/NP/SOP/140]
INITIAL CLIMB
The CLB panel of the FMS ACTIVE/PERF page displays the OPT FL and the REC MAX FL:
- The OPT FL is a function of the cost index (CI)
- The REC MAX FL provides the aircraft with a buffet margin of at least 0.3 g. The flight crew can enter a cruise flight level above this level in the FMS ACTIVE/PERF page, and the FMS will accept it, provided that it does not exceed the level at which the margin is reduced to 0.2 g.
What’s the main benefit of the DRTE CLB?
[FCTM/PR/NP/SOP/140]
CLIMB THRUST
Engine life may be extended by operating the engines at less than the maximum climb thrust.
The auto-derated climb slightly increases fuel consumption.
If you have an engine failure during climb out, how do you deselect auto-derate?
[FCTM/PR/NP/SOP/140]
CLIMB THRUST
If an engine failure occurs during an auto-derated climb, auto-derated climb thrust is deselected when the flight crew selects MCT.
In what situation would you use a rate of CLB/DES less than 1000 fpm, and for what reason?
[FCTM/PR/NP/SOP/140]
SMALL ALTITUDE CHANGES
The use of low values of V/S, e.g. less than 1000 ft/min can be appropriate for small altitude changes because the guidance is smoother and needs less thrust variations.
What speed gives the shortest time of CLB (or best rate of CLB), and what speed gives the shortest distance of CLB?
[FCTM/PR/NP/SOP/140]
SPEED CONSIDERATIONS
- Shortest TIME of CLB: speed given by CI = 0
- Shortest DISTANCE of CLB: G-dot.
During CLIMB, is it possible to reduce the speed below G-dot?
[FCTM/PR/NP/SOP/140]
SPEED CONSIDERATIONS
The flight crew should avoid reducing the speed to Green Dot (GD) at high altitude, particularly at heavy weight, because it can take a long time to accelerate to the ECON Mach. The flight crew should be aware that it is possible to select and fly a speed below GD but it does not bring any operational benefit.
How does the A/THR Soft Mode works?
[FCTM/PR/NP/SOP/150]
FMS USE
When in cruise, i.e. ALT CRZ appears on the FMA, the A/THR is in the SPEED/MACH mode, and the soft mode is available. The A/THR soft mode allows slight speed/Mach variation around the cruise speed/Mach (i.e. +/- 4 kt to 6 kt) while reducing the thrust variations. This optimizes the fuel consumption and increases passenger comfort.
[DSC/22-FG/50/50/B – A/THR Soft Mode]
Activation:
- A/THR is in SPEED/MACH
- AP is engaged
- ALT, ALT CST, ALT CRZ or DES is engaged
- At least 3 engines are operative
- Clean configuration, LG up, & SPD BRKs retracted
- Above FL180 & SPD target above Green Dot
- Speed/Mach control has not changed from Managed to Selected mode during the last 10 min
- SPD is not beyond the speed/Mach target ±∆ (Delta depends on the ALT).
Deactivation:
- One of the conditions required to activate the A/THR Soft mode is no longer met, or
- Selected speed target is changed, or
- SPD is beyond the speed/Mach target ±∆ for 4 s (Delta depends on the ALT).
What’s recommended to reduce workload when flying over high terrain?
[FCTM/PR/NP/SOP/150]
FMS USE
The flight crew can reduce their workload in the case of a diversion, if they prepare the potential en-route diversion in the secondary F-PLN. This is particularly true when terrain considerations apply to the intended diversion route. The flight crew should insert the ETP as a waypoint in the SEC, and they should finalize the route to the diversion airfield.
What’s the implication of high/low CIs?
[FCTM/PR/NP/SOP/150]
COST INDEX
CI=0 corresponds to the maximum range. CI=999 corresponds to the minimum time.
P.n.: flying G-dot gives the maximum endurance (best lift/drag ratio).
The flight crew can use the SEC F-PLN to check the predictions associated with the new CI. If they are satisfactory, the flight crew modifies the CI in the primary F-PLN.
In CRUISE, at high ALT, is it possible to reduce the speed below G-dot?
[FCTM/PR/NP/SOP/150]
SPEED CONSIDERATIONS
At high altitude, the flight crew should not reduce the speed below green dot. This can lead to a situation where it is not possible to maintain the speed and/or the altitude because the increased drag can exceed the available thrust.
What’s the impact of the temperature on the REC MAX FL?
[FCTM/PR/NP/SOP/150]
SPD Decay During CRZ
The REC MAX FL decreases when the OAT increases. The nearer the aircraft is to the REC MAX FL, the smaller is the thrust margin that the flight crew has to manage a speed decay during cruise. A continuous SPD decay during cruise phase may be due to:
- A large and continuous increase in tailwind or decrease in headwind, in addition to an increase in the OAT, that results in a decrease of the REC MAX FL.
- A large downdraft, when the flight crew flies (parallel and) downwind in a mountainous area, due to orographic waves. The downdraft may have a negative vertical speed of more than 500 fpm.
Therefore, if the aircraft is in a downdraft, the aircraft must climb in order to maintain altitude, and the pitch angle and the thrust value increase. Without sufficient thrust margin, the flight crew may notice that aircraft speed decays, but the REC MAX FL is not modified.
If the SPD goes below G-DOT, with the maximum available thrust in use, the only way to avoid an increase of AOA is to descend.
Note:
With the A/THR on, the selection of the OP DES mode reduces the thrust to idle, and therefore increases the time to recover the energy. P.n. hence use VS.
In cruise, the SPD goes below G-DOT, with the maximum available thrust in use. What do you do?
[FCTM/PR/NP/SOP/150]
SPD Decay During CRZ
If the SPD goes below G-DOT, with the maximum available thrust in use, the only way to avoid an increase of AOA is to descend.
Note:
With the A/THR on, the selection of the OP DES mode reduces the thrust to idle, and therefore increases the time to recover the energy. P.n. hence use VS.
In cruise, you face a FMS failure situation. How do you determine the OPT FL?
[FCTM/PR/NP/SOP/150]
ALTITUDE CONSIDERATIONS
If a FMS failure occurs, the flight crew should refer to the CRZ module of the IN-FLT PERF application in order to determine the OPT FL.
What’s the strategy to cope with cold fuel temperatures in flight?
[FCTM/PR/NP/SOP/150]
FUEL TEMPERATURE
If the fuel temperature approaches the freezing point, the flight crew should consider to achieve a higher TAT, by:
- Descending or diverting to a warmer air mass.
Below the tropopause, a 4 000 ft descent increases the TAT by 7 °C. In severe cases, the flight crew may need to descent to FL 250
- Increasing the Mach number.
An increase of M 0.01 increases the TAT by approximately 0.7 °C.
In either case, the flight crew can need up to one hour in order to stabilize the fuel temperature. They should consider the fuel penalty associated with either of these actions.
[Own notes]
Polar Ops:
The limitation of fuel temp is what limits the Polar Ops. This means, the moment the fuel temperature approaches the freezing point (i.e. -47° for Jet A1, or - 40° for Jet A), is when the crew is expected to come up with a plan (i.e. speed up, descend, or change route).
[FCTM] Throughout the flight, the Fuel temperature will slowly drop, until it matches with the TAT.
Alerts that might trigger crew action:
- COLD FUEL XFR Memo: triggered when any TK reaches -35°.
- ECAM FUEL LO TEMP: triggered when any TK reaches -40°.Notice that the triggering of the ECAM might be too late already to come up with a plan (cases when flying with more than 90% of Jet A - out of USA).RMK: observe that there is no ADV condition for fuel temperature. The ADV conditions available are only for ENG parameters, Pressurization and APU [FCOM/PRO/ABN/ABN-ADV].
[OMC-OFP Decodes]
Dispatch will not plan any route segments exposed to -65° for more than 90 min.
P.n.: a SAT of -68° would most likely produce a TAT of -40°.
So, the real problem is flying out of US (where Jet A is used). Out of Dubai is not a real concern (Jet A1).
