Fzra +fzra -fzra?

[comair1048]

I wanted to get an idea on what everyone's idea of severe icing is with regards to a forecast. For example which of these, -FZRA FZRA +FZRA or any combination with ice pellets, constitutes a forecast for severe icing. FARs state that no aircraft shall be dispatched into areas of known or forecasted severe icing but do not state what is considered severe icing in a forecast.

So I ask you all which of these TAF forecasts would you dispatch into. Also if your GOM specifically states which types of forecasts are legal to dispatch into I would like to see that as well.

 

[propsarebest]

Our books say that we can dispatch into -FZRA, and that's all. Some of the places that we fly, that is often the best wx.

 

[XPOO]

Go Evergreen, you ballsy bastards!

 

[propsarebest]

747 can take a lot of ice...

 

[PURPLEHAZE21]

Check your FA Area forecasts

 

[BushwickBill]

What kind of ice protection is on the tail of the 74? A friend mentioned no ice protection on the tail of a 76. How does this work in stuff like freezing rain?

 

[dbcooper71]

You really can't make the determination of severe icing in the forecast. FZRA in any format, whether TAF or METAR, is simply stating that precipitation is falling, or forecast to fall, and it is 0 Celsius or less. We have to rely on published airmets, sigmets and pireps and call the destination airport to see if the conditions are actually occuring. Regardless of what is occuring though, an alternate is required with that in the forecast or METAR if the flight is less than an hour.

 

[RVSM]

I think most opspecs allow you to dispatch to a destination forecast for FZRA at the arrival time, you just cant land unless the actual conditions are -FZRA. ( or takeoff for that matter.)
FZRA in the TAF is merely a forecast for freezing precipitation.
ICE AIRMETS & SIGMETS a "forecast" for severe icing.
PIREPS of severe icing are "known" severe icing

 

[BushwickBill]

Is this for a certain aircraft or for all aircraft in your fleet? What kind of aircraft does this include?

Cheers!

 

[homerjdispatch]

Here is SkyWest policy regarding FRZA:

1. Operation in Icing Conditions - 121.629
A. Aircraft may not be flown into known severe icing conditions. Severe icing
conditions mean: An icing condition that the aircraft deicing equipment cannot
handle.
........
4) Aircraft may be dispatched to an airport forecast for, or currently reporting freezing drizzle or freezing rain if the forecast for the time of arrival, PIREPS, or briefing information indicates that the conditions will not actually be occurring. An alternate airport must be specified on the flight release.
5) Freezing fog is not an indication of severe icing and does not preclude
dispatch or flight operations.
6) ASOS and AWOS will report freezing drizzle/rain when the temperature is
0°C or less and precipitation is falling. This does not necessarily indicate
actual freezing precipitation.
...
8) For additional information concerning operating in icing conditions, see the
applicable SOP appendixes, and the SkyWest Ground Deicing Program
Manual (SP2800). In all cases, the pilot-in-command will have the final
authority for the operation of the aircraft.
(italics and bold font added by me)​

So there!​

 

[B737Dvr]

huh???

What kind of ice protection is on the tail of the 74? A friend mentioned no ice protection on the tail of a 76. How does this work in stuff like freezing rain?

jet transports (at least the ones i have flown) all have no ice protection on the tail. not needed, due to the aerodynamics and negative lift profiles...

learjets, hawkers, falcons, boeing 727, 737 for my experience

 

[Occam's Razor]

jet transports (at least the ones i have flown) all have no ice protection on the tail. not needed, due to the aerodynamics and negative lift profiles...

learjets, hawkers, falcons, boeing 727, 737 for my experience

All DC-9 series aircraft have tail anti-ice systems. It's engine bleed air that also supplies the wing anti-ice.

 

[Flyoa1]

121.629 (a) is pretty subjective. However I think if you take a look at some of the research done by the NASA Icing Research guys after the ATR Roselawn accident, they hit the nail on the head and describe Supercooled Large Droplets (SLD) as water doplets larger than 50 microns, which includes freezing rain and freezing drizzle. I dont know of any airplane certified to fly in SLD. FAR 25 even outlines aircraft icing certification requirements only up to water drops as large as 40 microns. So anything over that = test pilot. Probably not a real good idea to be flying in freezing anything.

Kind of interesting that FAR 25 icing requirements only call for aircraft certification up to 40 microns, but NASA reports freezing rain and freezing drizzle are considered SLD and are 50 microns. hmmm?? Looks like the FAA didnt learn much from Roselawn.