Cold Weather Operations Flashcards
Engine Core Ice Shedding - Freezing Fog (RR only)
When freezing fog with a visibility of 300m or less is reported, crew need to follow Engine core ice shedding procedure for RR engines.
If take off cannot be achieved within 45 mins total taxi time then-
OAT 0 to -6, 50% N1 for 60 secs every 45 mins
OAT -6 to -13, 59% N1 for 60 secs every 45 mins
(Note you will get t/o config warning if you set 60%+ N1)
OAT < -13, manual de-icing is required.
If you do not accomplish core ice shedding within 45 mins but take off can be achieved within 60 mins total taxi time, take off is permitted but boroscope required within 10 flights.
If total taxi time exceeds 60 mins then engine must be manually de-iced.
Contaminted Runway
A runway is considered to be contaminated when a significant portion of the runway surface area (whether in isolated areas or not) within the required length and width being used is covered by one or more of the following: MORE than 3mm of water/wet snow/dry snow/slush, compacted snow or ice.
For contaminant depths up to and including 3mm standing water/slush/dry snow/wet snow the runway is NOT considered to be contaminated and WET runway data should be used.
Take off from contaminated or degraded braking action runways
Use Flow Chart (perf manual 4.3) to decided which data (Contaminated or Degraded) is most appropriate to use when taking off from a runway that is NOT dry or wet.
(Precipitation on ground or falling or ‘Braking action MEDIUM OR WORSE’ or ‘RWY PROMULGATED SLIPPERY WHEN WET’ should make you start thinking about this)
Observe following limitations:
1) If there is any doubt about the condition of snow especially when OAT is above -5 deg C TREAT IT AS SLUSH. (C)
2) A mixture of snow and slush MUST BE TREATED AS SLUSH. (C)
3) Check Max Crosswind Limitations! (C)
4) Reduces thrust take off NOT PERMITTED. (C & D)
5) No deficiencies in braking systems. I.e. Speedbrake, Reverse Thrust, wheel brakes and anti-skid. (C & D)
6) Use maximum runway distance available. (C & D)
7) Must consider: Nature and consequences of overrun and possible weather changes since last report. (C & D)
8) Visual guidance for take-off must be available from any of the following- Runway centreline lighting / markings, Runway edge lighting / markings. (C)
9) Minimum cleared width of 45m and symmetrical about centreline. (C)
10) PACKS may be ON or OFF. (C & D)
NOTE: Take-off with tailwinds greater than 5kts is NOT recommended. (C & D)
Note: performance data for contaminated runways assumes a uniform depth of contaminant along the entire length and width of the runway which is an unlikely situation.
Note: performance data for degraded braking action runways assumes the runway is NOT contaminated and has a uniform braking action along the entire width and length, which is an unlikely situation.
Take-off and Landing in Snow and Slush
Take-off and Landing is permitted in up to 10cms (4 inches) of dry snow using normal landing weights. Wet snow should be treated as slush and compacted snow as ice.
Take off and Landing in slush or excessive water deeper than 13mm (0.5 inches) or snow deeper than 10 cms should be avoided where possible as airframe damage could occur.
Cleared Widths and Snowbanks
The minimum RUNWAY width for landing is 45m. (150 ft)
The minimum CLEARED width for landing is 40m (130 ft). Symmetrical about centreline.
Snowbanks should NOT be located any closer than the runway edges. This means they cannot be located at a distance less than the given runway width. See table in perf manual
There are no snowbanks restrictions on take off. However allowable snowbank heights on landing should be considered in case they prevent an airborne return.
De/Anti Icing
The aircraft must be clear of all forms of frost, ice, slush and snow before take off, with the exception of -
- Thin hoar frost on fuselage, provided static vents are clear.
- Frost on underside of wing provided it is confined to general area of fuel tank and does not exceed 3mm
NOTE: ice ridges are NOT acceptable. (Bear in mind fuelling my warn aircraft up to prevent need for de-icing).
De-icing - typically heated and diluted type 1 fluids are used. Or technical/ manual de-icing - with brush or similar implement.
Anti-icing - typically unheated, undiluted type 2 or 4 fluids are used. (Thicker and provide longer protection times than type 1 fluids).
De-icing info via ACARS
-FIC.ICE (REG)
Hold Over Times
Sources-
Dynamic holdover times are available from the sure Wx app.
Static holdover times tables are provided for generic and common fluid specific products (see aide memoire in DocuNet)
Note - other fluid specific tables may be available at outstations.
Guidance-
Hold over times give an INDICATION of the time frame of protection that could reasonably be expected under conditions of freezing precipitation or active frost. However these times should not be considered as minimums or maximums as the actual time of protection maybe extended or reduced depending on the conditions existing at the time. In other words whatever the figure calculated, If deposits start to accumulate, the protection has expired.
Holdover times can only be used when de-/anti icing has been carried out with the flaps /slats retracted.
No guidance has been established for heavy snow, ice pellets, moderate and heavy freezing rain, small hail or hail.
With a one step the HOT begins at the start of the treatment. For a two step HOT begins at start of second (anti-icing ) step.
Holdover time will effectively have run out when frozen deposits start to form/accumulate on the aircraft surfaces.
Anti Icing Code
Written on OUTBOUND sector page of AML. It is the only place in AML where you will write LOCAL time and date.
Even if aircraft was treated before you arrive it must still be entered in the AML.
REMEMBER this section is only for the ANTI-ICING code. There is NO need for a tech log entry for de-icing only.
Icing Conditions
Icing conditions exist when OAT (on the ground) or TAT (in flight) is 10 deg C or below in any of the following conditions-
- visible moisture (clouds, fog with visibility of 1sm (1500m) or less, rain, snow, sleet, ice crystals and so on) is present, or
- ice, snow, slush, or standing water is present on the ramps, taxiways or runways.
Engine Start
Oil pressure may be slow to rise.
Initial oil pressure may be higher than normal.
Additional warm up time may be needed to allow oil temp to reach the normal range.
Displays may need additional warm up time before displayed engine indications accurately show changing values.
Displays may appear be less bright than normal.
Engine Anti-Ice Operation on the ground.
Must be selected on immediately after both engines are started or after landing and remain on during all ground operations when icing conditions exist or are expected, except when OAT is below -40 deg C.
Taxi-Out AND Taxi-In:
When anti-ice is required and OAT is 3 deg C or below, do engine run up -
CHECK AREA BEHIND AIRCRAFT IS CLEAR!
GE : min 50% N1 for 1 second every 15 mins
RR and -300s : min 50% N1 for 1 second every 60 mins.
// Also see engine core - ice shedding procedure //
Before Take-off:
RR: oil temperature must be at least 50 deg C before take-off.
When engine anti-ice is required and the OAT is 3 deg C or below must do static engine run up before take-off.
RR: 50% N1 and confirm stable before start of take-off roll.
All GEs: minimum 50% N1 and confirm stable, ensure engine vibration indications are below 4 units before start of take-off roll (should automatically pop up if the case - no need to display secondary engine indications).
In Flight:
Avoid prolonged operation in moderate to severe icing conditions.
Fan-Ice Removal-
IF moderate to severe icing conditions are encountered:
GE- with N1 settings at it below 70% or fan ice is suspected due to high vibration, fan must be cleared of ice: Reduce thrust towards idle then increase to a minimum of 70% N1 for 10 to 30 seconds (Every 15 mins one engine at a time).
RR: If fan ice is suspected due to high vibration, fan must be cleared of ice: quickly reduce thrust to idle for 5 seconds then restore required thrust. If vibration persists, advance thrust lever to 90% N1 momentarily. (One engine at a time).
Wing Anti-Ice
Do not use when TAT is above 10 deg C.
Used IN FLIGHT ONLY as an anti/de-icer.
Automatic system used as a DE-icer. (Preferred method)
Manual system used as an ANTI-icer.
Fuel Temperature
Prior to take-off:
GE: must not be less than -40 or 3 above fuel freeze point whichever is higher
RR: must not be less than -37 or 3 above fuel freeze point, whichever is higher.
In-flight tank temperature must be maintained at least 3 deg C above fuel freeze temperature.
Jet A : -40 deg C
Jet A1: -47 deg C
TS-1 or RT : -50 deg C
3 consecutive refuelling with a lower freeze point fuel should be completed before the lower freeze point can be used.
Rate if fuel cooling is approx 3 deg per hour towards TAT.
TAT can be raised by:
- Climbing or descending into a warmer air mass.
- Deviate to a warmer air mass.
- Increase Mach number.
