Missed Approach Procedure. The procedure to be followed if the approach… — Page 175, Lesson 179

I want to walk you through the missed approach procedure and the supporting details that follow in this excerpt. Let's start with the core definition. The missed approach procedure is exactly what it sounds like: the procedure to be followed if the approach cannot be continued. That's the official definition, taken from ICAO Doc 9365-AN/910, 2nd Edition, 1991. So if you're on an instrument approach and for any reason—weather, traffic, an unstable approach—you cannot complete the landing, you must execute the pre-published missed approach procedure. It's not optional; it's a mandatory, pre-planned escape path. Now, the excerpt gives us some abbreviations and values that relate to approach lighting and minima. You'll see "ALS out" — that means the approach lights are out of service. "TDZ or CL out" means the touchdown zone lights or centre line lights are out of service. These are critical because when these lighting systems are unserviceable, your landing minima—the minimum visibility or decision height you're allowed to use—may increase. The book doesn't spell that increase out here, but that's the significance: degraded lighting means higher minima. Next, we have a specific value: 3° and 803 feet per minute. That 3° is the standard glideslope angle for an ILS approach. The 803 feet per minute is the rate of descent you'd need to maintain on that 3° glideslope at a typical groundspeed. I don't have the exact groundspeed stated here, but that descent rate is the result of flying a 3° path. Then we get a precise location for the missed approach point, or MAPt. The excerpt says the MAP or MAPt is at 0.5 nautical miles from the ILL ILS DME, and that ILL DME is itself 0.5 nautical miles from the threshold. So the missed approach point is 0.5 NM from the DME, which is 0.5 NM from the runway threshold—meaning the MAPt is effectively at the threshold, or very close to it. You need to know that location precisely so you know exactly when to initiate the missed approach if you haven't acquired the required visual reference. We also see two values: 800 metres and 600 metres. These are likely visibility minima—the minimum visibility required to continue the approach or to land. Without more context from the surrounding pages, I can't tell you which applies to which category of aircraft or lighting configuration, but these are typical RVR or visibility values for precision approaches. Now, the excerpt gives us a formal definition of visibility from ICAO Doc 4444-RAC 501, 13th Edition, 1996. Visibility is the ability, as determined by atmospheric conditions and expressed in units of distance, to see and identify prominent unlighted objects by day and night. So it's not just "how far you can see"—it's specifically the ability to see and identify prominent unlighted objects, and it's expressed in units of distance, like metres or kilometres. That's the official definition you'll use in flight planning and in operations. Then the excerpt shifts to an example of a Standard Instrument Departure, or SID. This is a separate topic from the missed approach, but it's given here as Example 3. Let's go through it item by item. First, we have three SID designators: BPK 6F, BPK 6G, and BPK 6H. These are specific departure procedures from the BPK VOR/DME—likely different routes or different runway assignments. The procedure says: after take-off from runway 23, fly straight ahead. At a range of 2 NM from the LON Distance Measuring Equipment, or DME, turn right and intercept the 122° magnetic bearing from the BUR Non-directional Beacon, or NDB. That bearing of 122° magnetic from the NDB is the same as the bearing of 302° magnetic to the NDB—it's just the reciprocal. So you're intercepting a radial from the BUR NDB. Next, we have "X = a non-compulsory airspace fix." That means point X is a fix you don't have to cross—it's not mandatory—and it's located 6 NM direct from the LON DME, and 7 NM along the curved track. So the straight-line distance is 6 NM, but the actual flight path along the curved track is 7 NM. Then we see a frequency: 421 kHz. That's the frequency of the BUR NDB—non-directional beacons operate in the medium frequency band, and 421 kHz is a typical NDB frequency. Now, altitude constraints. There are three parts: i) Above 3500 feet but not above 6000 feet. ii) Above 4000 feet but not above 6000 feet. iii) At 6000 feet. These are likely altitude restrictions for different segments of the SID or for different aircraft categories. You must stay within those altitude bands as you fly the procedure. Next, a time calculation: ground distance is 32 NM, and at a groundspeed of 4 NM per minute, the estimated time of arrival, or ETA, is 0613 plus 8 minutes, giving an answer of 0621 UTC. So you're computing your time en route based on distance and speed. Then we have a speed limit: 250 knots indicated airspeed below FL100 unless otherwise cleared by ATC. That's a standard speed restriction in controlled airspace—below 10,000 feet, you're limited to 250 knots IAS unless ATC gives you a higher speed. The next part of the SID says: at 6 NM from the LON DME, turn right to intercept the 058° magnetic track to the CHT NDB. That track of 058° magnetic is the same as a bearing of 238° magnetic from the NDB—again, the reciprocal. Then at CHT, you intercept the 248 radial from BPK VOR/DME to fly inbound to the beacon. So you're transitioning from an NDB to a VOR radial. We also have two altitude values: 1080 feet on QNH and 1000 feet on QFE. QNH is the altimeter setting that gives you elevation above mean sea level; QFE gives you height above the airport elevation. So 1080 feet QNH equals 1000 feet QFE—that tells you the airport elevation is 80 feet. Then a climb gradient requirement: maintain a minimum climb gradient of 243 feet per nautical mile, which is 4%, up to 4000 feet. That's a performance requirement—your aircraft must be capable of that climb gradient to fly this SID safely. Next, 972 feet per minute. That's the rate of climb you'd need at a typical groundspeed to achieve that 4% gradient—similar to the descent rate we saw earlier, but for climb. Then we have 2100 feet and 1000 feet—likely altitude constraints or minima for different segments. Finally, transition level is given by ATC, and transition altitude is 6000 feet. Transition altitude is the altitude at which you change from the local QNH setting to the standard pressure setting of 1013.25 hPa. Below that, you use QNH; above it, you use standard pressure. Transition level is the flight level at which you change back when descending—and that's assigned by ATC, not fixed. So that's the full content of this excerpt: the missed approach procedure definition, approach lighting abbreviations, a 3° glideslope with its descent rate, the MAPt location, visibility minima, the formal visibility definition, and then a detailed SID example with all its bearings, distances, frequencies, altitudes, climb gradients, and speed limits.