Flight Plan Level and Airframe Icing: IREX

[FRQ Charlie Bravo]

Here's the question (yeah yeah, I've searched the forums and found some good info). Taken (roughly) from an IREX exam:

Given a surface temp, cloud levels, DALR and SALR to calculate a FZL (or should I say 'to calculate 0 deg C') of A064 along a particular route with LSALT of 5400 select an appropriate IFR cruising level for a West-bound aeroplane without de-icing equipment.

My thinking was that I could select A060 as this was above LSALT and Below 0 deg C.

Four doubts entered my mind:

1. Is the FZL at 0 deg C or +2 deg (where airframe-ice can begin forming)? I figured and still believe that it is at 0 deg.

2. Is there some strange buffer of 500 feet below the FZL for non-equiped aircraft?

3. As the cloud at A060 was less than 4/8 could I simply plan to remain out of icing conditions by avoiding cloud and rain (thereby avoiding icing conditions)

4. From a practical standpoint if there were some ice at A060 due to an inaccurate forecast could I, as an IFR flight, cruise at a VFR level of A055 or even at LSALT of A054 'due stress of weather'?

I chose to plan at A060 and I think that I got it right (I'm not sure because I may have gotten the other icing question wrong but the KDR doesn't differentiate). Much thanks in advance.

FRQ CB

PS No, I didn't copy the question and take it from the exam:=, the numbers are probably not exactly the same but pretty dam close.

[ForkTailedDrKiller]

Frq CB - I have no idea what the "book" answers are for your questions, but as one who regularly operates a non-deiced aircraft IFR, albeit not often, here's my best shot at answering your questions. I am sure someone in here will set us straight if I err.

My thinking was that I could select A060 as this was above LSALT and Below 0 deg C.

Four doubts entered my mind:

1. Is the FZL at 0 deg C or +2 deg (where airframe-ice can begin forming)? I figured and still believe that it is at 0 deg.

0 deg C works for me.

2. Is there some strange buffer of 500 feet below the FZL for non-equiped aircraft?

Not that I am aware of.

3. As the cloud at A060 was less than 4/8 could I simply plan to remain out of icing conditions by avoiding cloud and rain (thereby avoiding icing conditions)

Yes, if you remain clear of cloud you should be OK. Maybe the only issue then is drizzle from a overcast above you giving rise to freezing rain (??).

4. From a practical standpoint if there were some ice at A060 due to an inaccurate forecast could I, as an IFR flight, cruise at a VFR level of A055 or even at LSALT of A054 'due stress of weather'?

You don't need to be VFR to cruise at A054 - "Centre, XXX, request descent to (or traffic at) non-standard 5400"

I have a standard response to icing in the Bo:-

1) immediate 180 deg turn
2) descent to the LSA while I assess my options. I know there was no icing from whence I came.
3) If clear of icing I would do another 180 deg turn and proceed at the LSA - or track in another direction that would give me a lower LSA as soon as possible.
4) If I encounter icing again - go back to (1)

Personally, I would not fly in the conditions you describe without three (3) "outs"

1) 180 deg turn
2) descent of at least 500' to the LSA
3) the possibility of a turn onto another track with an LSA at least 1000' below the forcast freezing level

Hey, but I have been flying in Nth Qld for the last 21 years and icing scares the crap out of me. I know that guys and girls down south deal with it on a regular basis through winter.

I used to tangle with icing on a more regular basis in NZ, but there a turn to the east or west would generally quickly take you to a lower LSA.

Dr :8

[FRQ Charlie Bravo]

Thanks FTDK for that, very practical and methinks the books would have a hard time finding fault with it. Back to the books for me now. Oh and for anyone looking for some cool Airframe Icing lessons check out NASA's 'A Pilot's Guide to In-Flight Icing (http://aircrafticing.grc.nasa.gov/courses_inflight.html#)", Way cool.:cool:

FRQ CB