Visual Approaches
Ah, here's one that's stirring debate at Moncton ACC. The rules ATC have to follow for a visual approach. We'll cover the basics, then I'll explain the opening statement.
First off, in order for ATC to clear a pilot for a visual approach, or to approve a pilot's request for a visual approach, the weather must meet certain minima. I say it that way because unlike a Contact Approach, ATC may initiate a Visual Approach whereas a Contact Approach must be requested by the pilot. The weather minima include a minimum of 3SM visibility and a ceiling that is at least 500 feet above the minimum IFR altitude. The term "Minimum IFR altitude" confuses a lot of people, since there are so many altitudes that could be chosen Quadrantal altitudes, 100 NM safe altitudes, whatever. If a Minimum Radar Vectoring Altitude is established for the area, ATC will use that (note that MRVAs are not published for pilot reference). If none, they will look for something that is appropriate for the airspace concerned. The way this is arrived at flows something like this: The MRVA at CYQM is 1,800 feet ASL. The aerodrome elevation is about 200 feet, so that makes a ceiling requirement of 1,600 feet plus the 500 foot addition mentioned above, for a ceiling of 2,100 as a minimum for approving a visual approach (remembering that METAR cloud levels are heights above ground, rather than altitudes above sea level).
Once the weather minima are out of the way, ATC has to look at some other points. If the aircraft is number one, it's simple: The pilot merely has to report the field in sight. He doesn't have to be within a certain distance or anything fancy. If he's not number one, he has to see the aircraft he will be following. If he's not number one at the field, but the other aircraft is landing on another runway, he has to see that traffic and be instructed to maintain visual separation from him. ATC must take caution to ensure the correct aircraft is spotted in multiple aircraft situations, and will say the aircraft type in the clearance. For example, "... cleared for the visual approach runway 14, follow the Dash 8 on left base."
Pretty simple. Now, for the complications. It used to be common practice in a terminal environment that when, say, a Dash 8 is 6 miles final and the 2nd aircraft is 40 miles out, but calls the field in sight, ATC could clear the 2nd aircraft for the visual approach, using the applicable radar separation minimum to verify that positive separation exists. Hey, it should be good having over 10 times the minimum, right? What I understand is that it is still done that way across most of the country. In our FIR, though, things are different. They're telling us that this is not legal, and that number one must see number two, or we have to become the "visual nazi" -- no visual for you! They tell us it's a "national ruling", but nobody else in the country has received direction to operate this way. And it makes no sense, but we have to tell pilots "no" and leave them shaking their heads. In so many situations like the above, it would be impossible for one aircraft to catch another or even be within 10NM of the other, even if he wanted to. What more can I say? So much for consistency and common sense.
First off, in order for ATC to clear a pilot for a visual approach, or to approve a pilot's request for a visual approach, the weather must meet certain minima. I say it that way because unlike a Contact Approach, ATC may initiate a Visual Approach whereas a Contact Approach must be requested by the pilot. The weather minima include a minimum of 3SM visibility and a ceiling that is at least 500 feet above the minimum IFR altitude. The term "Minimum IFR altitude" confuses a lot of people, since there are so many altitudes that could be chosen Quadrantal altitudes, 100 NM safe altitudes, whatever. If a Minimum Radar Vectoring Altitude is established for the area, ATC will use that (note that MRVAs are not published for pilot reference). If none, they will look for something that is appropriate for the airspace concerned. The way this is arrived at flows something like this: The MRVA at CYQM is 1,800 feet ASL. The aerodrome elevation is about 200 feet, so that makes a ceiling requirement of 1,600 feet plus the 500 foot addition mentioned above, for a ceiling of 2,100 as a minimum for approving a visual approach (remembering that METAR cloud levels are heights above ground, rather than altitudes above sea level).
Once the weather minima are out of the way, ATC has to look at some other points. If the aircraft is number one, it's simple: The pilot merely has to report the field in sight. He doesn't have to be within a certain distance or anything fancy. If he's not number one, he has to see the aircraft he will be following. If he's not number one at the field, but the other aircraft is landing on another runway, he has to see that traffic and be instructed to maintain visual separation from him. ATC must take caution to ensure the correct aircraft is spotted in multiple aircraft situations, and will say the aircraft type in the clearance. For example, "... cleared for the visual approach runway 14, follow the Dash 8 on left base."
Pretty simple. Now, for the complications. It used to be common practice in a terminal environment that when, say, a Dash 8 is 6 miles final and the 2nd aircraft is 40 miles out, but calls the field in sight, ATC could clear the 2nd aircraft for the visual approach, using the applicable radar separation minimum to verify that positive separation exists. Hey, it should be good having over 10 times the minimum, right? What I understand is that it is still done that way across most of the country. In our FIR, though, things are different. They're telling us that this is not legal, and that number one must see number two, or we have to become the "visual nazi" -- no visual for you! They tell us it's a "national ruling", but nobody else in the country has received direction to operate this way. And it makes no sense, but we have to tell pilots "no" and leave them shaking their heads. In so many situations like the above, it would be impossible for one aircraft to catch another or even be within 10NM of the other, even if he wanted to. What more can I say? So much for consistency and common sense.
posted by Michael at
07:08
