So the very first time you speak to them, you tell them you're MNPSA-approved — Page 141, Lesson 217

I want to walk you through the next part of the MNPSA procedures. We've covered the basic requirements, and now we're looking at what happens when you actually operate in the North Atlantic airspace. Let's start with the clearance procedure. If you have MNPSA approval on the flight, you must advise ATC at your initial contact when you're requesting your oceanic clearance. So the very first time you speak to them, you tell them you're MNPSA-approved. After you get the clearance and read it back, your job isn't done — you then need to monitor your forward estimate for the oceanic entry point. If that estimate changes by three minutes or more, you must pass a revised estimate to ATC. That's a hard requirement: three minutes or more, and you update them. Now, here's a critical safety point that comes directly from accident and incident investigations in the North Atlantic. Pilots must pay particular attention when the issued clearance differs from the flight plan. Why? Because a significant proportion of navigation errors investigated in the NAT involve an aircraft that has followed its flight plan rather than its differing clearance. The clearance is what ATC has authorized; the flight plan is what you filed. If they don't match, you follow the clearance, not the flight plan. That distinction has caused real errors. There's also a specific responsibility when the entry point of the oceanic route you're cleared for differs from what you originally requested, or when the oceanic flight level differs from your current flight level. In either case, you as the pilot are responsible for requesting and obtaining the necessary domestic reclearance. ATC won't do it for you — you have to ask for it. Let me break down what an oceanic clearance actually contains. There are three elements: route, Mach number, and flight level. These three elements serve to provide for the three basic elements of separation: lateral, longitudinal, and vertical. So the route handles lateral separation, the Mach number handles longitudinal separation — because speed determines along-track spacing — and the flight level handles vertical separation. Every oceanic clearance gives you all three. Now let's talk about transition. The Organized Track System, or OTS, uses all the available flight levels as what we call 'one way streets'. That means traffic going one direction uses certain levels, and traffic going the opposite direction uses others. When an aircraft leaves the OTS and joins the domestic route system, an adjustment in flight level may be required. To make sure this adjustment only happens where there's no loss of separation, special areas called transition areas have been established. On the eastern side of the NAT region, we have two specific transition areas. First, the Shannon Oceanic Transition Area, abbreviated SOTA, which lies west of Ireland out to 15 degrees west. Second, in the Bay of Biscay, we have the Brest Oceanic Transition Area, or BOTA. These are ostensibly special rules areas where the normal rules of the air are not complied with. That's a significant statement — in these transition areas, the standard right-of-way rules and other normal rules of the air don't apply in the usual way because the separation is being handled differently to facilitate the transition between oceanic and domestic airspace. Finally, a quick note on SSR — Secondary Surveillance Radar. When flying in the NAT region, you are to maintain the last assigned SSR code from the domestic ATC unit. You don't change it unless instructed. That code stays with you as you enter the oceanic environment.