Reply To: Approach/Landing Climb – Inflight Icing Penalty

Welcome to SAPOE Forum Member Forum Approach/Landing Climb – Inflight Icing Penalty Reply To: Approach/Landing Climb – Inflight Icing Penalty

#459
Chet Collett
Participant

Let me try again and see if I can clarify my issue:

The Boeing AFM uses the terminology of “possible ice accumulation” when it talks about the need to apply the Inflight Icing Correction to the Landing and Approach Climb Limit Weights. It seems clear that the intent of this correction is associated with structural icing conditions. Unfortunately, in the same paragraph Boeing uses the generic term of “icing conditions” which is defined later in Chapter 4 as it relates to when engine anti-ice should be used.

Section 4 Page 3:
7. Aircraft performance adjusted for possible ice accumulations is provided for planning flights into known or anticipated icing conditions.

Climb Performance: Performance for en route climb, approach
climb and landing climb accounting for possible ice accumulation
is provided in AFM-DPI by selecting “Inflight Icing”. Use the
en route “Inflight Icing” performance when operating in icing
conditions during any part of the flight. Use the approach
climb and landing climb “Inflight Icing” performance when
operating in icing conditions during any part of the flight and
the forecast landing temperature is below 10 degrees C.

=====

Section 4 Page 7:
D E F I N I T I O N S (Continued)

ICING CONDITIONS
Icing conditions exist when the OAT on the ground and for takeoff, or TAT inflight, is 10 degrees C (50 degrees F) or below and visible moisture in any form is present (such as clouds, fog with visibility of one mile or less, rain, snow, sleet and ice crystals).

Icing conditions also exist when the OAT on the ground and for
takeoff is 10 degrees C (50 degrees F) or below when operating on ramps, taxiways or runways where surface snow, ice, standing water or slush may be ingested by the engines or freeze on engines, nacelles or engine sensor probes.

We are convinced that it is safe and appropriate to clarify our guidance to the dispatchers that they should only apply this Inflight Icing Penalty when the flight is planned through anticipated structural icing conditions and the forecast landing OAT <10 degrees C (< 8 degrees C for the 737-400).

Unfortunately, our Compliance Department is concerned that our FAA may interpret the AFMs use of the generic term “icing conditions” in “operating in icing conditions during any part of the flight” as “TAT inflight, is 10 degrees C (50 degrees F) or below and visible moisture in any form is present (such as clouds, fog with visibility of one mile or less, rain, snow, sleet and ice crystals)” rather than “structural icing conditions”

As a result, we have Dispatchers applying this Inflight Icing Correction when it is raining and 8 degrees C at the departure station (NO Structural Icing is anticipated anywhere along the route of flight) and the arrival forecast temp is colder than 10 degrees C.

Hence why I asked what I thought was the simple question:

What is your trigger for applying the Inflight Icing Correction? Is it based on anticipated inflight structural icing conditions, or is it based a flight segment where the “TAT inflight, is 10 degrees C (50 degrees F) or below and visible moisture in any form is present”?

Thanks for your responces,

Chet Collett
Director, Flight Operations Engineering
Alaska Airlines
206-392-6024
303-246-0386 Cell