"I should now be at that altitude?!" - Unsuspecting IFR students
There are some type of approaches that you just never do. And then there are those that you don't even see in training very often: they might be slowly dying (NDBs), or not available in your area (PARs and ASRs).
We in the Savannah area are lucky to have both Hunter Army Airfield (KSVN) and Beaufort Marine Corps Air Station (KNBC MCAS) that can perform non-precision radar approaches. There is both a non-precision and precision flavor to radar approaches:
Airport Surveillance Radar (ASR) - lateral guidance only
Precision Approach Radar (PAR) - lateral and vertical guidance
In a way, these are the most basic approaches in existence - they don't require any equipment on board. The ASR approach must be requested by the pilot and can be granted only if certified controllers are present and there is sufficient personnel to cover multiple TRACON frequencies.
I now make all my IFR students experience one. Here's a video of flying the KARW ASR approach to runway 25 through Beaufort Arrival.
The Idiot's Guide
After you request the ASR, the controller will provide you with the following information:
The approach you will execute (in our case, "ASR to KARW runway 25").
The minimum descent altitude (MDAs are also published under "Radar Minimums" in the TERPS).
The missed approach point (MAP) - in our case at KARW it's 1 NM from the runway.
They will then switch you to a dedicated isolated frequency so that there won't be any interruption by other radio traffic. Just you and them. You will receive vectors and altitudes to fly until approaching the final approach course (FAC). At that point the controller will switch you to the final controller who will:
Remind you of the procedure
Inform you that they will give you vectors to fly and theoretical altitudes each mile after a five-mile final until the MAP. So in essence they tell you where to fly laterally and based on a stabilized descent from the FAF at what altitude you should theoretically be at to make the minimums before the MAP.
They will then advise you to NOT REPEAT their instructions. This is because they may be quick and precise (e.g., "turn right 157 degrees").
On a 5 NM final they will instruct you to descend to MDA. You don't choose when - they tell you.
When you're 4 NM, 3 NM, and 2 NM from the runway they will also include the theoretical altitudes. Trust me... you'll be high... It's important to note that the mileage callouts are from the runway because on a PAR they are from the touchdown point... It's a big difference, as the accuracy of a PAR is far more finite. ASR is not as accurate as it only sees your primary target with your secondary beacon transmitting your altitude and speed. On a PAR, ATC has both glideslope & azimuth on a scope designed specifically for that approach. An ASR is conducted off the main radar scope so the finite accuracy down the FAC is not as precise as a PAR.
They will ask you to report runway in sight. If they don't and you reach the MAP, they will give you missed approach instructions.
This is what the controllers' screens look like.
So, in summary: FLY THE HEADINGS THEY GIVE YOU. It's like being on vectors all the way to the MAP. Descent to MDA when they tell you.
Something interesting is that you need to speak with the controller the entire time. So if you do an approach to a towered field, you will land without ever talking to tower. At an uncontrolled field - you need to figure it out. You an split COMMs, or at least ask the controller if they have any targets over your destination.
NOTE: The video and article were reviewed for accuracy by an experienced ATC controller at KNBC. Thank you, Travis!!
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