IFR Circling missed appr obstacle clearance
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Joined: Nov 2009
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From: Near Montreal
IFR Circling missed appr obstacle clearance
Looking for comments on circling missed approach obstacle clearance requirements. Generally we say that once you are beyond the circling protected zone for the circling MDA, the next obstacle clearance altitude is the MSA in the absence of any other IFR min altitudes published on the chart or min vectoring altitude provided by ATC. So this creates a step from circling MDA to the next min IFR altitude until established on the missed approach track. This creates the imperative to climb over the airport within the circling boundries until at the next IFR altitude or established on the missed appr track.
Say the missed appr procedure was an extension of the original appr runway, and the missed was commenced while lined up to land on an intersecting runway, so you can either turn 270 deg over the airport the long way to pick up the missed appr track overhead, or turn directly toward the missed approach fix and intercept the track that way. However, say the geometry is such that turning the direct way may take you through space that is outside the circling boundry, below the next highest IFR altitude, and not quite in the protected airspace of the missed appr track.
Now, say you looked at the intended landing runway's departure data and it was a standard 1/2 vis takeoff procedure, which means after 400 agl there is 200 ft/nm gradient for obstacle clearance in ANY direction until the gradient crosses the next IFR min altitude. Can you take credit for that conical obstacle clearance gradient for your landing runway when determining if it is safe to go outside the circling area while below MSA for your original missed approach procedure?
In other words, on your missed approach from the intersecting runway, can you consider that the same as a departure from that runway from an obstacle clearance perspective and consider it safe to climb and turn outside the circling limits of the airport to intercept the track for the correct missed approach as long as you are climbing enough to meet the departure gradient requirement for that runway? After all, if you departed that runway you can turn to any heading after 400 ft and you would have obstacle clearance assured as long as you climb 200 ft/nm.
Say the missed appr procedure was an extension of the original appr runway, and the missed was commenced while lined up to land on an intersecting runway, so you can either turn 270 deg over the airport the long way to pick up the missed appr track overhead, or turn directly toward the missed approach fix and intercept the track that way. However, say the geometry is such that turning the direct way may take you through space that is outside the circling boundry, below the next highest IFR altitude, and not quite in the protected airspace of the missed appr track.
Now, say you looked at the intended landing runway's departure data and it was a standard 1/2 vis takeoff procedure, which means after 400 agl there is 200 ft/nm gradient for obstacle clearance in ANY direction until the gradient crosses the next IFR min altitude. Can you take credit for that conical obstacle clearance gradient for your landing runway when determining if it is safe to go outside the circling area while below MSA for your original missed approach procedure?
In other words, on your missed approach from the intersecting runway, can you consider that the same as a departure from that runway from an obstacle clearance perspective and consider it safe to climb and turn outside the circling limits of the airport to intercept the track for the correct missed approach as long as you are climbing enough to meet the departure gradient requirement for that runway? After all, if you departed that runway you can turn to any heading after 400 ft and you would have obstacle clearance assured as long as you climb 200 ft/nm.
