Commercial and Business Aviation Advisory Circulars

Notice to Air Operators - Net Take-Off Flight Path - Implementation Date for Cross-Wind Accountability

INTRODUCTION

The purpose of this Air Carrier Advisory Circular (ACAC) is to notify affected air operators of an extension to the Canadian Aviation Regulations (CARs) implementation date with respect to the consideration of cross-wind during net take-off flight path obstacle planning.

BACKGROUND

CAR Part VII currently requires air operators to consider the obstacle clearance provided by their net take-off flight path under the following circumstances:

Sub Part 704

(1)  RVR 1200 take-offs involving the carriage of 10 or more passengers; and

(2)  large or turbo-jet operations not conducted in accordance with relief provisions set out in the Commercial Air Services Standards.

Sub Part 705

All take-offs not conducted in accordance with relief provisions set out in the Commercial Air Services Standards.

ISSUE

When considering net take-off flight path obstacle clearance, the consideration of wind is described as follows:

"...the wind component at the time of take-off, where not more than 50 per cent of the reported headwind component or not less than 150 per cent of the reported tailwind component is considered..."

The intent of this wording is to ensure that obstacle clearance relates to the actual ground track described by the departing aircraft, including any lateral drift caused by wind. This interpretation is consistent with information provided by the United States Federal Aviation Administration (FAA) and the International Civil Aviation Organization (ICAO).

In attempting to meet the CAR requirements, many operators have encountered difficulty in resolving a wind-corrected ground track. While the ICAO "splay" provides adequate wind protection, it is overly conservative for operators of high-speed aircraft and generally exceeds the requirements of the CARs. Many operators have long used the FAA "still-air corridor" based on a zero-drift ground track when analyzing net take-off flight path requirements despite the lack of regulation requiring such steps. These operators face potentially expensive transition costs to a system accounting for cross-wind.

POLICY

Transport Canada recognizes the effort that operators have put forth in accounting for obstacles, in many cases ahead of any regulatory requirement. We further recognize that many operators have been hampered in their attempts to comply with cross-wind accountability through events that are beyond their control.

The excellent safety record which Canadian operators have with respect to engine-out obstacle clearance incidents supports a medium-term extension to the implementation of cross-wind accountability as a low-risk step toward full compliance.

IMPLEMENTATION PROVISIONS

The Canadian Aviation Regulation Advisory Council (CARAC) Performance Standards Working Group will be convened in March of 1998, with a primary mandate to examine the various options open to operators for complying with obstacle clearance and to address issues such as interface with Air Traffic Control (ATC) for engine-out departure paths that do not comply with ATC clearances. The Working Group is expected to present its recommendations to the Commercial Air Service Operations committee (CASO) before the end of 1998.

The compliance period during which air operators need not consider cross-wind during net take-off flight path computations will continue until six months after the recommendations of the Performance Standards have been accepted by CASO. The compliance date and conditions will be announced in a future Advisory Circular.

Operators currently using the FAA zero-drift "corridor" may continue to do so until the compliance date determined by CASO.

Where the departure path is devoid of obstacles, operators may continue to use the FAA "corridor" indefinitely, thereby avoiding transition costs.

CONCLUSION

The information in this ACAC supersedes any previous directives concerning cross-wind accountability and serves as official notice of the extension of the implementation date for the applicable provisions of CAR Sub Parts 704 and 705.

M.R. Preuss
Director
Commercial and Business Aviation