Aircraft Operations. Volume II - Construction of Visual and Instrument ...

Part I — Section 4, Chapter 1 I-4-1-3
1.8.2 The criteria taken into consideration for the classification of aeroplanes by categories is the indicated
airspeed at threshold (Vat) which is equal to the stall speed Vso multiplied by 1.3 or stall speed Vs1g multiplied by 1.23
in the landing configuration at the maximum certificated landing mass. If both Vso and Vs1g are available, the higher
resulting Vat shall be used.
1.8.3 The landing configuration which is to be taken into consideration shall be defined by the operator or by the
aeroplane manufacturer.
1.8.4 Aircraft categories will be referred to throughout this document by their letter designations as follows:
Category A — less than 169 km/h (91 kt) indicated airspeed (IAS)
Category B — 169 km/h (91 kt) or more but less than 224 km/h (121 kt) IAS
Category C — 224 km/h (121 kt) or more but less than 261 km/h (141 kt) IAS
Category D — 261 km/h (141 kt) or more but less than 307 km/h (166 kt) IAS
Category E — 307 km/h (166 kt) or more but less than 391 km/h (211 kt) IAS
Category H — see 1.8.8, “Helicopters”.
1.8.5 The ranges of speeds (IAS) in Tables I-4-1-1 and I-4-1-2 are to be used in calculating procedures. For
conversion of these speeds to TAS, see Part I, Section 1, Appendix to Chapter 1.
1.8.6 Permanent change of category (maximum landing mass). An operator may impose a permanent, lower,
landing mass, and use of this mass for determining Vat if approved by the State of the Operator. The category defined
for a given aeroplane shall be a permanent value and thus independent of changing day-to-day operations.
1.8.7 Restrictions on category and IAS. Where airspace requirements are critical for a specific category of
aircraft, procedures may be based on lower speed category aircraft, provided use of the procedure is restricted to those
categories. Alternatively the procedure may be designated as limited to a specific maximum IAS for a particular
segment without reference to category.
1.8.8 Helicopters
a) The stall speed method of calculating aircraft category does not apply to helicopters. Where helicopters are
operated as aeroplanes, the procedure may be classified as Category A. However, specific procedures may be
developed for helicopters and these shall be clearly designated “H”. Category H procedures shall not be
promulgated on the same instrument approach chart (IAC) as joint helicopter/aeroplane procedures.
b) Helicopter-only procedures should be designed using the same conventional techniques and practices as those
pertaining to Category A aeroplanes. Some criteria such as minimum airspeeds and descent gradients may be
different, but the principles are the same.
c) The specifications for Category A aeroplane procedure design apply equally to helicopters, except as
specifically modified herein. The criteria that are changed for helicopter-only procedures are appropriately
indicated throughout the text.
1.8.9 For precision approach procedures, the dimensions of the aircraft are also a factor for the calculation of the
OCH. For Category DL aircraft, additional OCA/H is provided, when necessary, to take into account the specific
dimensions of these aircraft (see Part II, Section 1, Chapters 1 and 3 and Part III, Section 3, Chapter 6 (GBAS Cat I)).
23/11/06