ATPL · Navigation · Radio Navigation Atpl Ground Training Series… lesson — Page 276, Lesson 271

Right, let's walk through the RTE page — the route page — on the FMS, which is Figure 16.9. This is where you build the actual flight plan, the route you intend to fly. The layout is a grid of lines, and each line has a left-hand side and a right-hand side, labelled 1L, 1R, 2L, 2R, and so on. So, at line 1L, you input the departure aerodrome, and at 1R, the destination aerodrome. The data is valid only if it's an ICAO aerodrome designator held in the database — that's the four-letter code like EGLL for London Heathrow. If you already typed that ICAO identifier on the POS INIT page, the position initialization page, then it will automatically appear at 1L for you. Moving down, at 2L you insert the company route — that's the standard, pre-defined route your airline has stored — and at 2R, the flight number. Then at 3L you have the runway in use, and at 4L the SID — the standard instrument departure — and the first route waypoint. Now, here's a nice touch: if those are already defined within the company route you selected, they will automatically appear in those fields. You don't have to retype them. At line 5L you have the airway, and at 5R the next reporting point on that airway — and the example given is airway V2. Both of these are inserted by the computer automatically from the database. So the FMS is pulling that information for you. Now, to see the subsequent pages of the route, you select the NEXT PAGE function key on the keyboard. That lets you check or modify the route as needed. Then, at line 6R, there's a prompt that directs you to activate the route. When you press 6R, it illuminates the EXEC key on the CDU — the control display unit — and you should then press that EXEC key for the computer to action the route after take-off. Here's the sequence after take-off: the RUNWAY line is cleared, and the VIA/TO moves up to line 3, with the next waypoint appearing at line 4. And as you pass an active waypoint, line three is cleared and replaced with the next active waypoint. So the route display rolls forward as you fly. Now, with that done, the pre-flight actions for the navigation profile are complete — but note, the performance initialization is yet to be actioned. That's dealt with elsewhere in the course. The computer will check the conditions against the performance data and the required cost index profile, and it will inform the pilots of the power, speed, and configuration needed to achieve the required profile. So it's telling you how to fly the aircraft to match the plan. If you need a manual input of a route — rather than using a company route — you can do that through the scratchpad, and the same applies to any modifications to the standard company routes. Finally, let's cover the valid formats for navigational inputs, because the FMS is strict about this. Latitude and longitude can be entered either as a 7-group alphanumeric, like N05W010, or a 15-group, like N0926.3W00504.7. And here's a critical detail: the leading zeros must be entered for the FMC to accept the position. So you can't drop them. For other identifiers — ICAO aerodrome designators, reporting points, navigation facilities, airway designators, and runway designators — you can use up to 5 alphanumerics. Examples would be EGLL for an aerodrome, KODAP for a reporting point, DHD for a navigation facility, A23 for an airway, and so on for runway designators. So that's the RTE page: you build the route, activate it with the EXEC key, and the FMS rolls the waypoints forward as you fly.