Special Operational Procedures and Hazards — Page 144, Lesson 230

I want to walk you through the structure of the Operations Manual — the OM — because it's the master document that tells every pilot and operator exactly how to fly safely. The OM is split into two main parts: Part A and Part B, and each covers a different category of procedures. Let's start with Part A. Under the heading 'Operating Procedures', Part A contains all the policies, instructions, and procedures that are not type-related — meaning they apply generally, regardless of which specific aeroplane model you're flying. These are the non-type-related items needed for safe operation. The book lists several key items that must be included here. First, de-icing and anti-icing on the ground — that's the procedures for removing ice and snow from the aircraft and preventing it from forming before take-off. Next, adverse and potentially hazardous atmospheric conditions — things like thunderstorms, icing in flight, wind shear, and volcanic ash. Then wake turbulence — the disturbed air left behind by other aircraft, especially heavy ones. Also incapacitation of crew members — what to do if a pilot or cabin crew member becomes unable to perform their duties. The use of the Minimum Equipment List and Configuration Deviation List — we'll get into those in a moment. Security — procedures for unlawful interference, hijacking, or threats. And handling of accidents and occurrences — how to report and manage incidents. Still under that same 'Operating Procedures' heading in Part A, there are also detailed policies for the use of specific safety systems: altitude alerting systems, which warn you if you deviate from your assigned altitude; Ground Proximity Warning Systems, or GPWS, which alert you if you're getting too close to terrain; and TCAS/ACAS — the Traffic Collision Avoidance System / Airborne Collision Avoidance System, which helps prevent mid-air collisions. Now, Part B of the OM is different. Under the heading 'Aeroplane Operating Matters - Type Related', Part B contains all the instructions and procedures that are specific to a particular aeroplane type or variant. These procedures take into account differences between types, variants, or even individual aeroplanes used by the operator. The following items are specifically included in OM Part B: abnormal and emergency procedures — the checklists for things like engine failure, fire, or system malfunctions; the Configuration Deviation List, or CDL; the Minimum Equipment List, or MEL; and emergency evacuation procedures — how to get everyone off the aircraft quickly and safely. Let's focus on the Minimum Equipment List — the MEL — and its parent document, the Master Minimum Equipment List, or MMEL. The MEL is applicable up to the commencement of flight. That's an important phrase. It means you can use the MEL during taxi and right up to the point when the flight actually begins. If there is a conflict between any airworthiness directive — a mandatory safety directive from the aviation authority — and the MEL, the airworthiness directive overrides the MEL. So the AD takes priority. Now, the book gives us two key definitions you need to know. First, commencement of flight: this is defined as the point when an aeroplane begins to move under its own power for the purpose of preparing to take-off. So it's not when the engines start — it's when the aircraft actually starts moving, under its own power, with the intention of getting ready for take-off. That's the moment the MEL stops being applicable. Second, inoperative: this means the equipment does not accomplish its intended purpose or is not consistently functioning within its design tolerances or limits. But here's an important nuance — some equipment is designed to be 'fault tolerant'. That means it can still work correctly even if a component inside it has a fault. These systems are monitored by computers, which transmit a fault message to a centralized computer for maintenance purposes. The book makes it clear: just because a fault message appears does not necessarily mean the equipment is inoperative. The equipment might still be functioning within its tolerances despite the message. So you need to understand the difference between a fault indication and actual inoperability.