Cold weather operations Flashcards
(116 cards)
1
Q
What is aquaplanning (hydroplanning)?
A
Tires of the aircraft are seperated from the runway surface by a thin fluid film.
2
Q
What is contamination? 4
A
All forms of frozen or semi-frozen moisture such as frost, snow, slush or ice.
3
Q
What is contamination check?
A
When you check the aircraft to establish the need for de-icing.
4
Q
De-icing is applied?
A
Heated to ensure maximum efficiency.
5
Q
What is dew point?
A
Temperature at which water vapor starts to condense.
6
Q
What is friction coefficient?
Normal force depends on?
A
Friction coefficient is the relationship between the friction force acting on the wheel and the normal
force on the wheel.
The normal force depends on the weight of the aircraft and the lift of the wings.
7
Q
The start of the holdover time is?
A
From beginning of the anti-icing treatment.
8
Q
What is post-treatment check?
A
External check of the aircraft after de-icing and or anti-icing to ensure that the aircraft is free from any frost, ice, snow or slush.
9
Q
Icing conditions generally occur from?
A
Slightly positive temperature down to -40 and are most likely around FL100.
10
Q
When rapid icing is encountered in a stratiform cloud
A
Moderate change of altitude will significantly reduce the rate.
11
Q
If icing conditions prevail on the approach, what should we do?
A
Keep speed as high as permitted, delay flap extension as much as possible and do not retract flaps after landing.
12
Q
Which ice is not visually detected?
A
Clear-ice.
13
Q
If aircraft is not clean we need to de-ice to remove everything. When do we use anti-icing?
A
When outside conditions may lead to an accumulation of percipitation before take-off = holdover time.
14
Q
Published tables for hold-over times should be used as?
A
Guidance only, parameters like severe weather, high wind velocity, jet blast etc may AFFECT it.
15
Q
How does RWYCC work?
A
Reporting process begines with evaluation of the runway by human observation and are then transffered to ATC and we use it to calculate our performance. We should also use our own observation after landing if it´s more poor than the reported condition.
16
Q
How does the ground spoilers brakes the aircraft?
A
Increases the drag and improves the brake efficiency by adding load on the wheels.
17
Q
How does the thrust reversers brake the aircraft?
It is very important on?
A
Thrust reversers decelerate the aircraft by creating a force opposite to the aircraft’s motion regardless of the runway’s condition.
The use of thrust reversers is essential on contaminated runways.
18
Q
Hard contaminants are?
Fluid contaminants are?
A
Compacted snow and ice and reduce the friction forces.
Water, slush and loose snow = reduce the friction forces and created an additional drag and may lead to aquaplanning.
19
Q
In crosswind conditions the pilot may have to choose between?
A
Braking and controlling the aircraft.
20
Q
Taxi, take-off, and landing operations in X conditions are prohibited
A
LESS THAN POOR
21
Q
GOOD TO MEDIUM REPORTED, maximum crosswind and RWYCC?
A
RWYCC 4, 20kt.
22
Q
MEDIUM reported, maximum crosswind and RWYCC?
A
RWYCC 3, 15kt.
23
Q
MEDIUM TO POOR reported, maximum crosswind and RWYCC?
A
RWYCC 2, 10kt.
24
Q
Take-off and landing is permitted only when reported RWYCC is equal to X or higher.
A
RWYCC 3. For
performance calculations and crosswind limitations maximum RWYCC 3 may be used.
25
When runway is reported DAMP, crew can use runway condition
WET instead of Slippery Wet,
unless the airport publishes lower RWYCC.
26
The presence of a contaminant on the runway leads to an increased accelerate-stop distance, as well
as an increased accelerate-go distance (due to the precipitation drag). This results in?
If this limitation occur, what can we do?
A lower take-off
weight which can be significantly impacted when the runway is short.
Higher than standard flap setting and take-off speeds can be used. Results in better runway performance since both the accelerate-stop and accelerate-go distances are reduced.
27
On short and contaminated runway, it normally calls for? Bear in mind?
Higher flap setting (2 instead of 1) = ASDA is reduced = we climb before. Bear in mind that if you have obstacle during climb-put requires lower flaps setting as it provides better climb performance.
28
V1, VR and V2 also have a significant impact on the take-off performance.
Contaminated runway calls for?
High speeds generate good climb performance but we spend long time on runway = take-off distances are increased. Not recommended on contaminated runways.
For lower speeds. Presence of an obstacle may limit the speed reduction and right balance must be found.
29
Maximum freezing point for JET A?
Maximum -40 degrees.
30
Temperature below ISA?
Aircraft true altitude below indicated altitude.
31
Basic mechanism for aircraft icing?
Supercooled droplets?
Water at negative Celsius temperature may remain liquid = supercooled (unstable). They can freeze all of a sudden if they are bit by an object expecially if the object is at negative temperature.
32
On ground, when does the airframe may get covered with frost?
Overnight, if the sky is clear and temperature gets around 0 degrees or below.
33
CB clouds are a special threat, why?
Because icing conditions can be met outside of the cloudy body for example under the anvil, generates freezing drizzle or freezing rain = lead to severe ice.
34
Speed as an effect on several characteristics of ice which accretes. Best known as? Temperature recovery?
Kinetic heating (KH) which is difference between TAT and SAT. KH is sometimes called temperature recovery because it naturally heats the leading edge relative to the rest of the airframe = naturally heats leading edge protects from icing as long as the OAT is above -10 degrees.
35
At 250kt, the kinectic heating KH is about?
+ 10 degrees = temperature increase by 10 degrees of the leading edge = good.
36
Why can we not expect icing when SAT it 40 degrees or below?
Because no supercooled water may be present at colder temperatures.
37
Increase of the speed does what?
Decreases the amount of ice accreted because of the kinetic heating KH.
38
If rapid ice accretion is met, what can we do?
Moderate change of altitue is normally enough to decrease or stop the ice to accrete. ATC must accept such a pilot request.
39
Aircraft designers do their best to ensure airframes have smooth surfaces (wind leading edge, upper surface). WHY?
Smoothness in these areas produces best lift force. Any type of ice accretion is an obstacle to smooth airflow. Any obstacle will slow the airflow down and introduce turbulence and will degrade the lifting performance of the wing.
40
Aircrafts are not certified for sustained icing in configurations?
With slats and flaps out. Delay them. Aircraft wouldn´t stay long enough in icing conditions with slats/flaps extended.
41
How do we protect the engines and leading edges from icing on air?
We switch anti/wing ice on before ice accretes. All Airbus wing and nacalle (engine intake) ice protection systems use hot bleed air type anti-icing from the compressors HP.
42
Engine intake: In certain flight conditions, the temperature may drop by several degrees inside the intake (“sucking” effect). Therefore?
Therefore, inside icing may occur at
slightly positive outside air temperatures, whilst the wing itself wouldn’t. We should use the engine anti-ice.
43
What is covered by electrical heating on Airbus?
Sensors, static ports, pitot tubes, TAT and AOA probes, flight compartment windows are electrically anti-iced.
44
When does icing condition exists? 2
What must we immediatly to if we see these conditions?
OAT on ground or TAT in flight is AT or below 10 degrees and visible moisture in any form is present (clouds, fog, rain, snow etc).
OAT on ground and for take off is AT or below 10 degrees and operating in ramps, taxiways or runways where surface snow, standing water or slush may be ingested by the engines or freeze on engines, nacalles or engine sensor probes.
Turn on the engine anti-ice.
45
When SAT is below 40 degrees engine anti ice must be on only when?
When entering CB clouds.
46
Why should we avoid to fly in icing conditions with slats and flaps extended?
Accreted ice may block the retraction of the high lift devices causing mechanical damage to the slat/flap system.
47
Icing conditions on the ground can be expected when air temperatures fall below?
Precipitation may be? 3.
Frost can occur due to?
0 degrees and when moisture or ice occurs in the form of either precipitation or condensation.
Rain, sleet or snow.
Condensation of fog or mist (negative OAT and clear skies).
48
Radome: Attention must be taken to the fact that melted snow can flow down and can formulate?
Ice close to the ports which can disturb air flow and can cause disturbances in speed and/or altitude indication.
49
Clear ice layer can form on the wing upper surfaces when aircraft on ground. How can we seet it from below the wing?
Frost on the underwing surface.
50
What is freezing fog?
FZFG. Water droplets which freezes upon impact with the ground or other objects, reducing horizontal visibility to less than 1km.
51
What is sleet?
Precipitation in the form of a mixture of rain and snow.
52
What is snow grains?
SG, precipitation of very small white grains of ice. Diameter less than 1mm. For holdover time purposes, treat snow grains as snow.
53
What is active frost?
When forst is forming. When aircraft surface temperature is: At or below 0 degrees and at or below dew point.
54
What is blade ice?
Forms on the back side of fan blades overnight in a humid atmosphere and temperatures close to or below 0 degrees. Must be removed with hot air before dispatch.
55
What is clear ice?
How can it be removed?
Crystal clear and solid layer of ice on the top of airplanes critical surfaces which can not be detected visually, only with hands (tactile). Formed by slow freezing of large super cooled droplets from freezing fog, drizzle or rain. Can be formed up to +15 degrees OAT because of rain and drizzle.
Only by de icing fluid.
56
What is cold-soak effect?
When wings contain very cold fuel as a result having landed after a flight at high altitude. When precipitation falls on coal-soak aircraft on ground = clear ice may occur.
57
What is frost/hoar frost?
Forms by the process of sublimation when temperature of the surface and the dew point are both below freezing. Water vapor changes directly to ice in form of frost. Can be formed in clear air when aircraft is parked in sub-zero temperatures. Melts after sunrise.
58
What is rime ice?
Whitish of ice, small super-cooled water droplets caused by freezing fog, drizzle or rain) on any part of the airplane.
59
What is slush?
Water saturated with snow. Encountered at temperature around 5 degrees.
60
Possible effects of frozen surfaces are? 8
Loss of lift, more drag, more weight, increase of stall speed, less efficient flight controls, loss of engine thrust, fan/engine vibration, incorrect reading on instruments.
61
What is acceptable on the upper surface of the fuselage?
On the underside?
Thin hoar frost.
Maximum layer of 3 mm of frost.
62
What are the critical surfaces?
Leading edges and upper surface of the wings, vertical and horizontal stabilizers, all control surfaces, slats and flaps
63
On ground, clear ice layer or frost can form on the wing upper surfaces = frost on the underwing side. Very hard to see this type of ice/frost. Why it happens? 2
1. Low temp of fuel that was added during previous stop and/or the long airborne time of previous flight = wing tanks below 0 degrees.
2. Abnormally large amount of remaining cold fuel in wing tanks causing the fuel level to be in contact with the wing upper surface panels as well as lower surface.
64
The information report (de-icing/anti-icing) given to cockpit is a part of the?
General transfer to the operational responsibility takes place when?
Technical airworthiness of the aircraft.
At the moment aircraft starts moving by its own power.
65
We have ice/frost on the aircraft = we must de-ice heated. When do we anti-ice?
When freezing precipitation existsband there is a risk of precipitation at the time of dispatch.
66
When do we do one step and what does it mean? When does holdover time start?
Two-step? When does holdover time start?
Single application of heated de-icing/anti icing = shorter holdover time. Beginning of the application of the fluid.
Longer holdover time, must be applied consecutively. Beginning of the second fluid.
67
What is local de-icing?
Ehat about the HoT?
Removal of local of contamination. When no precipitation is falling or expected, a local area de-cing may be required = only contaminated areas, generally found on the wing and/or stabilizer leading edges ot in patches on the wing and/or stabilizer upper surfaces.
Not applicable for local de-icing.
68
What is active frost?
Frost is actually forming. Frost has actually formed on the airplane, but frost no longer forms at the time of de-icing.
69
What does Type II/100 mean?
What does Type II/75 mean?
100% type II fluid.
75% fluid and 25% water.
70
Under some conditions, HoT guidelines does not exist. When? 5
Moderate/heavy freezing rain, ice pellets, and hail, heavy snow, high wind velocity, fast dropping OAT.
71
What is Type I fluid?
Provide a very limited protection against re-freezing during precipitation conditions. = limited hold over time. Low viscocity which only changes depending on temperature and flows of the wing much better.
72
How can we increase the HoT?
By increasing the concentration of the fluid in the fluid/water mix.
73
What is the idea of using type II fluid?
What happens during take-off?
The fluid form a thicker liquid on aircraft surfaces. Longer hold over time by lowering the freezing point. The freezing point rises all the time water is added.
Shear forces emerge paralell to the airflow = with increasing speed, the viscosity decreases drastically and the fluid flows off the wing.
74
Anti-icing fluid forms a protective layer, describe how it works
It keeps the freezing temperature of the fluid well below OAT or aircraft skin temperature = preventing frozen precipitation to accumulate. When we have precipitation, the layer becomes more and more diluted (utspädd) = freezing temperature increases until it reaches OAT or aircraft skin temperature = hold over time is over.
75
What is the maximum validity of a SNOWTAM?
8hrs.
76
What is specially prepared winter runway?
Which RWYCC can we expect if we hear specially prepared winter runway?
Runway with dry frozen surface of compacted snow or ice, or both, which has been treated with sand or grit to improve runway friction.
RWYCC 4.
77
Aircraft deceleration is obtained by: 4
Brakes, aerodynamic drag, air brakes (spoilers) and thrust reversers.
78
By applying the brakes, how do we slow down?
Wheel is slowed down and creates a force opposite to the aircraft motion.
79
Thrust reversers create?
Force opposite to aircrafts motion includng significant decelerating force which is independent of the runway contaminant.
80
How does thrust reversers effect perforance on dry, wet and contaminated runways?
On dry = they don´t affect. On wet and contaminated = we should use it, it helps a lot.
81
Why is the oppsite friction force created by the wheels when braking on wet runways reduced?
WHat about fluid contaminated runway (water, slush, loose snow)
What about hard contaminated runway? (compacted snow and ice)
Because water cannot be completly squeezed out from between the tire and the runway = only partial contact with the runway with the tire.
Similar to wet, same reason.
Wheel just roll over it as for dry runway but with reduced friction force (because of ice or snow between runway and wheels)
82
The reduction of friction forces also significantly reduces?
Aircraft directional control.
83
What does the pilot needs to choose on slippery runways sometimes and why?
When maximum braking efficiency is reached, a significant part of the steering capability is lost. Total driction force is reduced = choose between braking and controlling the aircraft. Not both at the same time.
84
Difference between CONF 1+F and higher flaps setting for take off?
Low flaps setting (CONF 1 + F ) = good climb performance (good lift to drag ratio) while TOF distance is longer = bad runway performance.
A higher flap setting helps to reduce the TOF distance but has less climb performance.
85
Which flap setting should we depart from contaminated runways and why?
Higher flap setting because we will lift of earlier but if you have obstacle you need to take it into considerations because with higher flaps setting = less climb performance.
86
Which RWYCC should we use if we have different on the thirds of the runway?
The worst scenario = the lowest RWYCC.
87
Freezing point for JET A1 AND JET A?
Fuel temperature sensors is installed in each outer and inner tank. When do we get ECAM advisory? Warning?
JET A1 = -47C AND JET A = -40C.
As soon as fuel temperature in any tank reaches -40C. Warning = -45 degrees.
88
The pressure barometric alitimeters installed are calibrated?
If temperature is lower then ISA?
To indicate true altitude under ISA conditions. Any deviation from ISA = incorrect reading whereby the indicated altitude differs from the true altitude.
ISA to low watch out below = True altitude of the aircraft will be lower than indicated. = we do temperature correction.
89
When the atmosphere
differs from the ISA conditions, the altitude and FPA computed by the ADIRS, and the associated
indications on PFD (altitude, VDEV, ...)
Are not accurate. When temperature lower than ISA = The true altitude of the aircraft is lower than the altitude that the ADIRS computes.
* The FPA that the aircraft actually flies, is less steep than the FPA that the ADIRS computes.
= we must apply corrections to altitudes and FPA.
90
In vertical selected mode FPA, to correct the FPA for this ISA deviation effect, the flight crew should
select on the FCU a FPA slightly different from the FPA that the aircraft needs to fly.
We need to descent with steeper, maybe with -3,3 instead of -3.0. Altitudes (corrected in temperature) versus distance remains the reference.
91
When the engine anti-ice is on, the N1 limit is automatically X and the idle N1 is automatically
X for both engines, if necessary, in order to provide the required pressure.
Reduced
Increased
92
When does window heating and probes heating come on? 2
At least one engine is running (or when aircraft is in flight) or manually before engine start when crew switches ON the PROBE/WINDOW HEAT pushbutton switch.
93
On the ground, which probes are not heated?
TAT.
94
Take-off is prohibited in the following weather conditions:
Take-off is prohibited in the following weather conditions:
* On a runway contaminated by "ice" and no reported braking action
* Heavy snow (+SN)
* Heavy snow pellets (+GS)
* Heavy snow grains (+SG)
* Heavy ice pellets (+PL)
* Moderate/heavy freezing rain (FZRA, +FZRA)
* Moderate/heavy hail (GR, +GR)
95
When is reduced thrust take-off (FLEX TO) not permitted?
On contaminated runways. We always do TOGA takeoff.
96
Limitations for inexperienced flight crew members are in force for operations on contaminated runways.
Only FOs with a minimum of 1500 hrs of Airbus FBW experience and CPTs are allowed to act as PF on
contaminated RWYs/taxiways/aprons
97
Auto roll-out guidance is demonstrated on?
Dry and wet runway. Not contaminated.
98
WARNING - Pilots must turn on the engine anti-ice system, when temperature and visible
moisture meet these criteria, and should not wait until they see ice building up.
OAT (on ground or after TOF) or the TAT (in flight) is at or below 10C and visible moisture is present (clouds, fog with visibility less than 1600m, rain, snow)
OAT on ground below 10 degrees, Standing water, snow, slush may be ingested bu the engines.
99
How about Engine Anti ice during descent?
MUST BE ON before and during a descent in icing conditions EVEN if the SAT is below 40 degrees.
100
Icing conditions are severe when there is approximately X mm of ice accretion on the airframe.
5mm.
101
You do disptach calculation, which two dispatch calculations should you do?
With no wind = unable?
Witch current wind = unable?
1: No wind.
2: Probable wind.
Dry and wet = no dispatch. Contaminated = 2 alternate aerodromes required.
1 alternate aerodrome required for dry,wet and contaminated.
102
IRL alignment time when it is cold?
15 minutes.
103
How should we remove ice from the back of the blades?
Air from low flow hot air, such as cabin heater.
104
De-icing after pushback and before engine start:
Pushback done after before start checklist completed.
105
De-icing after engine start. Procedure is?
When clear signal is receiver from ground crew?
When does PM select flaps?
When clear signal received from ground crew (de-icing)?
Pushback and start procedures are done normally. After start flow = normally EXCEPT that the selection of the take-off flap setting is postponed.
PF will announce "AFTER START CHECKLIST POSTPONED, REQUEST TAXI CLEARENCE".
On completion of de-icing, PM complete the after start flow scan = flaps 1.
PF orders AFTER START CHECKLIST.
106
The flaps extension, trim settings and flight control check should take place
After de-icing.
107
On contaminated runways, taxi speeds should be limited to?
10kt.
108
When is antiskid not active?
Below 20kt.
109
Engine anti-ice increases ground idle thrust which means?
Acceleration is faster.
110
What about "On slush-covered, or snow-covered, taxiways:" about flaps and checklist.
It should be delayed until reaching the holding point. When reaching holdingpoint we must do the CHANGE OF RWY/INTERSECTION CHECKLIST.
111
After engine shutdown:
* Make a visual inspection to determine that the flap/slat mechanism is free of contamination.
* When the mechanism is clean, use the following procedure to retract the flaps/slats before the
aircraft electric network is de-energized
- Set the YELLOW ELEC PUMP to ON
- Check that the BLUE ELEC PUMP is in the AUTO position
- Set the BLUE PUMP OVRD to ON
- Retract the FLAPS and monitor retraction on ECAM page.
- Select off the YELLOW ELEC PUMP and BLUE PUMP OVRD and resume with normal
procedure.
112
Before the aircraft lines up on the runway for take-off, the flight crew must ensure that the airframe has
no ice or snow.
Then, before applying thrust, the Captain should ensure that the nose wheel is straight. If there is a
tendency to deviate from the runway centreline, this tendency must be neutralized immediately, via
rudder pedal steering, not via the tiller.
Rudder pedal steering, not via the tiller.
113
APPROACH: If significant ice accretion develops on parts of the wing, what should we do?
The aircraft speed must be increased
114
The FMS vertical profile does not take into account the effect of low OAT. Therefore, vertical managed
guidance:
Must not be used when the actual OAT is below the minimum temperature indicated on the
approach chart or defined by the Operator, or not be used when temperature corrections are required (FINAL APP mode may not engage). Selected vertical guidance may still be available.
115
Contaminated runway, what reverse setting? Autobrake?
Using reversers on a runway that is contaminated with dry snow may
reduce visibility, particularly at low speeds.
MAXMUM REVERSE THRUST and AUTOBRAKE MEDIUM RECOMMENDED.
In such cases = reverse thrust should be reduced to idle.
116
If there is a problem with directional control after landing: 3
1. Reverse thrust should be set to idle, in order to reduce the reverse thrust side-force component.
2. The brakes should be released, in order to increase the cornering force.
3. The pilot should return to the runway centreline, reselect reverse thrust, and resume braking
