Ones and Zeros

There are basically two kinds of navigational beacons used for aviation: NDBs (non-directional beacons) and VORs (VHF Omni-Range beacons). The former are the older type of beacon. An automatic direction finder (ADF) indicator gauge in the plane has a needle that just points directly to the beacon. If I’m crabbing into the wind so I can track a straight course line over the ground, the needle still points to the beacon which is now not on my nose anymore. So it shows all my cross-wind adjustments.

Many planes don’t have an ADF (see the box with three knobs on the right) anymore since many of the NDBs nationwide have been decommissioned, including many in my area. Mine plane has an ADF, and it works. So when I take my IFR examination I’ll have to demonstrate working with an NDB.

Today we’re flying to an available local NDB, it is inside the SFRA (ADIZ) so I’ll have to file specially for that. We’re not going to land at that airport, so I put “IFR airwork” in the flight plan. This causes some confusion later with ATC, I should have just put “airwork”.

I’m flying with instructor R today. He briefs the lesson and it all seems so straightforward right now, here on the ground with no turbulence and no plane to fly. My job as a pilot with NDBs is to maintain the necessary heading to or from that beacon. In a crosswind I need to adjust for the wind direction by angling the plane toward the wind somewhat. This means that the ADF pointer will point away from my heading by the amount I have to angle the plane. That amount is determined by the wind’s strength, it’s direction and my speed.

If I keep the ADF pointer straight ahead, but the directional gyro (DG) keeps turning then I’m homing in on the beacon by following an arc to the beacon. I’m not tracking a straight course over the ground. I have to keep the directional gyro straight, and the ADF steady too. But in the presence of wind, the ADF will point to the side by the amount of my wind correction.

Once R and I are in the plane and I’m tracking toward the NDB this all becomes harder. I’m still having to keep the plane straight and upright by instruments alone (my view below). And we’re getting bounced around a bit. Our plan is to fly the approach course, then do the missed approach turn and follow the approach course away from the NDB, then do the procedure turn and follow the approach course again. All this is meant to be at the same altitude, we’re not doing the vertical descent part of the approach or the climb of the missed.

Meanwhile, Potomac ATC wants to know what we’re doing and to help us, we need to contact CTAF at the airport near the NDB so the other traffic there knows what we’re doing too.

With R’s help this all works. He has mercy on me and handles most of the radio calls. He has me peek out under my foggles to see the airport just below us. But the numbers and headings are hard work for me. I’m using too many neurons just flying to make the rest of it smooth. And since this is my first time with it I don’t have enough practice to make this automatic.

Three times around; follow the course inbound, follow the missed approach procedure to turn to the outbound course, then after a one minute count, turn right 45 degrees to prepare for the procedure turn. Then turn 180 degrees and re-intercept the course inbound again.

R seems satisfied enough at the end. I feel beat up. I’ve got to get this more automatic. R recommends working out scenarios on paper with the DG and ADF. I plan to do so. I also plan to try this out on my planned X-Plane flight sim at home too.

This entry was posted on Monday, March 9th, 2009 at 10:34 and is filed under aviation, flying. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.