Let's go through them in order — Page 180, Lesson 183

I want to walk you through a set of chart-reading items from a Jeppesen-style airway or en-route chart. These are the kinds of labels and annotations you will see on a real flight-planning chart, and each one carries a specific operational meaning. Let's go through them in order. Starting with item 15. You see "FL90" written on the chart. That stands for the Minimum En Route Altitude, abbreviated MEA, expressed as a Flight Level. The MEA is the lowest published altitude between two radio fixes. It does two things: first, it meets obstacle clearance requirements between those fixes, and second, in many countries it also assures acceptable navigational signal coverage. The MEA applies to the entire width of the airway, segment, or route between the radio fixes that define that airway, segment, or route. So when you see FL90 as an MEA, you know that between those two fixes, you must not descend below Flight Level 90 unless you have specific clearance or a different published altitude. Next, item 15 also shows "1900a". This is the Jeppesen Route Minimum Off-route Altitude, or MORA. The MORA provides reference point clearance within 10 nautical miles of the route centre line, regardless of the actual width of the route, and also clearance for the end fixes. The clearance criteria are: the MORA clears all reference points by 1000 feet in areas where the highest reference points are 5001 feet AMSL or lower, and by 2000 feet where reference points are 5001 feet or higher. So "1900a" means the MORA for that route segment is 1900 feet, and the 'a' is a Jeppesen coding convention. Moving to item 16. You see "19" written, which stands for Grid Minimum Off-route Altitude, or Grid MORA. This is an altitude derived by Jeppesen or provided by State Authorities. The Grid MORA altitude provides terrain and man-made structure clearance within the section outlined by latitude and longitude lines. Importantly, the MORA does not provide for navaid signal or communication coverage. So it is purely a terrain and obstacle clearance number. The chart will reference a glossary for the exact terrain clearance criteria. Item 17 gives a waypoint: LOGAN, with coordinates N5144.9 E00136.5. That is a named intersection or fix, and its latitude and longitude are given in degrees and decimal minutes. Item 18 tells you the scale and a typical cruising level: 1 inch equals 20 nautical miles, and the chart shows FL200 as a relevant altitude. Item 19 gives you the vertical limits of controlled airspace for two countries. For the UK, the airspace shown extends from FL245 to FL660. For France, it extends from FL195 to FL660. Item 20: FL460. That is a specific altitude, likely a cruising level or a ceiling for a particular sector. Item 21: FL260. Another specific altitude. Item 22 gives two frequencies: 129.35 MHz and 131.25 MHz, and the controlling unit is PARIS UAC — that is Paris Upper Area Control. Item 23: 5°W. That is a line of longitude, likely a boundary or a reference meridian on the chart. Item 24 describes a compulsory reporting point. It says "A compulsory reporting point overhead the DIEPPE VOR (no DME) frequency 115.8 MHz; the flag is aligned with local magnetic north." So at DIEPPE, you have a VOR without DME, on 115.8 MHz, and you are required to report when overhead. The flag symbol on the chart is aligned with local magnetic north, which tells you the orientation of the VOR's radial system. Item 25: "CRUISING LEVELS AVAILABLE ONLY: UR1 between Midhurst and ORTAC. Northbound FL250 etc ....... see box N4930 E/W0000." This means that on airway UR1, between the fixes Midhurst and ORTAC, only certain cruising levels are available. For northbound traffic, FL250 is one of them, and you need to refer to the box at latitude N4930, longitude E/W0000 for the full list. Item 26: another scale notation: 1 inch equals 10 nautical miles. This may apply to a different portion of the chart or a different chart altogether. Item 27: two frequencies: 121.15 MHz and 119.85 MHz. These are likely communication frequencies for a sector or approach control. Item 28: "Aircraft are controlled by PARIS CONTROL, with radar available, frequency 127.3 MHz." So in this area, Paris Control provides radar service on 127.3 MHz. Item 29: 3°W. Another longitude reference. Item 30: "068°(M), 59.5 NM." That is a magnetic bearing of 068 degrees and a distance of 59.5 nautical miles — likely a radial and distance from a navaid, or a leg between two fixes. Item 31: 3000 feet. That is an altitude, possibly a minimum altitude or a transition altitude. Item 32: "HOLDING PATTERNS. Refer to respective STAR/ARRIVAL charts for holding information. (see south of DIEPPE)." This tells you that holding pattern details are not on this en-route chart; you must look at the Standard Terminal Arrival or arrival charts for that information, and there is a holding area south of DIEPPE. These are the exact annotations you will interpret on a Jeppesen chart. Each one gives you a piece of the operational picture: altitudes, frequencies, reporting requirements, airspace limits, and route structure.