Above FL340: Mach 0.83 in all conditions — Page 175, Lesson 173

I want to walk you through a section from an approach chart — this is the kind of detail you’ll see on a real instrument approach plate. Let’s start at the top. Above FL340, the speed is Mach 0.83 in all conditions. That’s a fixed Mach number — no variation for wind or temperature — and it applies whenever you’re above flight level 340. This comes from ICAO Doc 8168, Volume 1, page 4-3. Next, we have a value: 80 feet — that’s a height, likely a minimum altitude or a step-down fix altitude on the approach. Then, KENET is labelled as a non-compulsory airspace fix. That means you can overfly it, but you’re not required to cross it — it’s there for reference, not a mandatory crossing point. For LON: it’s defined by a VOR radial of 277 degrees and a DME distance of 37 nautical miles. For OCK: VOR radial 293 degrees, DME 40 nautical miles. So these are two separate fixes, each defined by a radial and a DME range from their respective VOR/DME stations. SLP stands for Speed Limiting Point. That’s a specific location on the chart where a speed restriction begins. The symbol X marks a non-compulsory airspace fix, and the shaded square marks the Speed Limiting Point. So on the chart, you’ll see an X for non-compulsory fixes and a shaded square for the SLP. Now, the speed restriction itself: “Maintain MAX IAS 250 KT from position 3 min before holding facility or position (SLP) shown on chart.” That means you must not exceed 250 knots indicated airspeed starting from a point that is three minutes before you reach the holding facility or the Speed Limiting Point shown on the chart. So you need to plan your deceleration so that you’re at or below 250 knots by that three-minute-before point. Pilots should plan for a possible descent clearance as follows: for the OCK 1F arrival, you should plan to be at FL140, 10 nautical miles before Nigit Intersection. So if you expect a descent, you’d aim to reach flight level 140 by that point. Then we see 37 nautical miles — that’s a distance, likely the DME range from a station, probably the same one mentioned earlier. Next, we have three items under a sub-list. First, HON — that’s a VOR or NDB identifier, a navaid. Second, 113.65 MHz — that’s the frequency for that navaid. Third, DME capability is indicated by a small letter “D” preceding the VOR frequency. So if you see a small “D” before the frequency number on the chart, that tells you the VOR station also has DME. Now, the holding pattern or racetrack pattern. Inbound to the OCK VOR on the 332-degree radial. Outbound from overhead the VOR onto a track of 152 degrees magnetic, to a maximum range of 9 nautical miles from the OCK DME — that’s D9, meaning DME distance 9. And 7000 indicates the minimum holding altitude, or MHA. So you hold at or above 7,000 feet in that pattern. Then we jump to Example 2, which is an approach chart. First item: Heathrow Director, Approach Control Radar available, frequency 119.72 MHz. So that’s the frequency for Heathrow Director, who provides radar approach control service. Second item: the altimeter setting information is given in hectopascals — inches of mercury are available on request. The runway elevation of 3 hectopascals — which equals 3 millibars — corresponds to roughly 90 feet. That 3 hPa value is the barometric pressure equivalent for the QFE altimeter setting. You subtract this value from the reported QNH setting to obtain QFE. And the height reference datum will be either the runway threshold elevation, the airport elevation, or the runway touchdown zone elevation, as applicable. So when you set QFE, the altimeter reads height above that chosen datum — threshold, airport, or touchdown zone — depending on what’s published for that approach. That covers the entire excerpt. You now have the speed limit above FL340, the definitions of the fixes and symbols, the holding pattern geometry, and the altimeter-setting procedure for QFE.