page-274

468

14 CFR Ch. I (1–1–19 Edition)

Pt. 25, App. O

maximum icing conditions defined in Appen-
dix C of this part.

(2)

Holding ice

is the holding ice defined by

part II, paragraph (c)(4), of this Appendix, for
an airplane certified in accordance with
§ 25.1420(a)(2), or defined by part II, paragraph
(a)(4), of Appendix C of this part, for an air-
plane certified in accordance with
§ 25.1420(a)(1), plus:

(i) Pre-detection ice as defined by part II,

paragraph (b)(5), of this Appendix; and

(ii) The ice accumulated during the transit

of one cloud with a 17.4 nautical miles hori-
zontal extent in the most critical of the
icing conditions defined in part I of this Ap-
pendix and one cloud with a horizontal ex-
tent of 17.4 nautical miles in the continuous
maximum icing conditions defined in Appen-
dix C of this part.

(iii) Except the total exposure to holding

ice conditions does not need to exceed 45
minutes.

(3)

Approach ice

is the more critical of the

holding ice defined by part II, paragraph
(b)(2), of this Appendix, or the ice calculated
in the applicable paragraphs (b)(3)(i) or (ii) of
part II, of this Appendix:

(i) For an airplane certified in accordance

with § 25.1420(a)(2), the ice accumulated dur-
ing descent from the maximum vertical ex-
tent of the icing conditions defined in part I
of this Appendix to 2,000 feet above the land-
ing surface in the cruise configuration, plus
transition to the approach configuration,
plus:

(A) Pre-detection ice, as defined by part II,

paragraph (b)(5), of this Appendix; and

(B) The ice accumulated during the transit

at 2,000 feet above the landing surface of one
cloud with a horizontal extent of 17.4 nau-
tical miles in the most critical of the icing
conditions defined in part I of this Appendix
and one cloud with a horizontal extent of 17.4
nautical miles in the continuous maximum
icing conditions defined in Appendix C of
this part.

(ii) For an airplane certified in accordance

with § 25.1420(a)(1), the ice accumulated dur-
ing descent from the maximum vertical ex-
tent of the maximum continuous icing condi-
tions defined in part I of Appendix C to 2,000
feet above the landing surface in the cruise
configuration, plus transition to the ap-
proach configuration, plus:

(A) Pre-detection ice, as defined by part II,

paragraph (b)(5), of this Appendix; and

(B) The ice accumulated during the transit

(4)

Landing ice

is the more critical of the

holding ice as defined by part II, paragraph

(b)(2), of this Appendix, or the ice calculated
in the applicable paragraphs (b)(4)(i) or (ii) of
part II of this Appendix:

(i) For an airplane certified in accordance

with § 25.1420(a)(2), the ice accretion defined
by part II, paragraph (c)(5)(i), of this Appen-
dix, plus a descent from 2,000 feet above the
landing surface to a height of 200 feet above
the landing surface with a transition to the
landing configuration in the icing conditions
defined in part I of this Appendix, plus:

(A) Pre-detection ice, as defined in part II,

paragraph (b)(5), of this Appendix; and

(B) The ice accumulated during an exit

maneuver, beginning with the minimum
climb gradient required by § 25.119, from a
height of 200 feet above the landing surface
through one cloud with a horizontal extent
of 17.4 nautical miles in the most critical of
the icing conditions defined in part I of this
Appendix and one cloud with a horizontal ex-
tent of 17.4 nautical miles in the continuous
maximum icing conditions defined in Appen-
dix C of this part.

(ii) For an airplane certified in accordance

with § 25.1420(a)(1), the ice accumulated in
the maximum continuous icing conditions
defined in Appendix C of this part, during a
descent from the maximum vertical extent
of the icing conditions defined in Appendix C
of this part, to 2,000 feet above the landing
surface in the cruise configuration, plus
transition to the approach configuration and
flying for 15 minutes at 2,000 feet above the
landing surface, plus a descent from 2,000
feet above the landing surface to a height of
200 feet above the landing surface with a
transition to the landing configuration, plus:

(A) Pre-detection ice, as described by part

II, paragraph (b)(5), of this Appendix; and

(B) The ice accumulated during an exit

(5)

Pre-detection ice

is the ice accretion be-

fore detection of flight conditions in this Ap-
pendix that require exiting per § 25.1420(a)(1)
and (2). It is the pre-existing ice accretion
that may exist from operating in icing condi-
tions in which the airplane is approved to op-
erate prior to encountering the icing condi-
tions requiring an exit, plus the ice accumu-
lated during the time needed to detect the
icing conditions, followed by two minutes of
further ice accumulation to take into ac-
count the time for the flightcrew to take ac-
tion to exit the icing conditions, including
coordination with air traffic control.

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