Another thread mutated from a discussion on upper level winds into a discussion on pilots no longer knowing how to use an ADF properly. Not wanting to further hijack that thread I’ve created a new one for this question.
Are there any airfeilds in the US which are serviced by an NDB only? If so, how many?
I recently saw a photo of the cockpit of a new Piper Seminole (I think). As far as I could see, it didn’t have an ADF at all, only a VOR or two. Were my eyes deceiving me or are some aircraft not even fitted with an ADF now days?
By “serviced by an NDB only” I assume you mean “the only instrument approach is NDB-based.”
For that I can’t help, but I know that in the US airline biz nowhere we go (including our emergency and alternate fields) is NDB-only.
As to aircraft without ADFs, yes, they’re going away. For any new small plane, all the avionics are options, so they’re equipped with whatever the buyer wants. And I’d bet damn few, at least outside Alaska, are buying ADFs.
The Boeing 717 has ADFs available only as an extra optional feature. When I checked out on that airplane I was pleased to find our company hadn’t bought the option, so we no longer had to struggle through the stupidity of trying to manuever a fast jet through a 1920s manuever.
LOMs are also just about gone. I remember reading somethinga few years ago that the FAA wasn’t repairing them. Whenever one broke, it was decommissioned for good. No new big airports or new runways at big airports have them.
Yes there are general aviation airports that have only NDB approaches. I’ve seen them but have no idea how many exist, probably a small number. The US has just over 5000 public-use airports. NDB’s are not terribly accurate so they are on the way out. The reason airports still have them is simply monetary and that an NDB is better than nothing. If you are really interested in finding this out, try contacting AOPA (www.aopa.com). The other option would be heading out to your closest airport and paging through the NOAA approach plates for the whole country.
Your eyes are probably just fine Death Ray, so long as you know what you’re looking for. Any airplane fitted with an IFR-approved FMS or GPS receiver does not really need an ADF. A pilot with this equipment may substitute an NDB or NDB fix with area navigation. Almost all nav aids are now in the GPS and FMS databases to assist the pilot in programming. In my experience with FMS and GPS overlay fixes, they are much more accurate than an actual NDB.
I figured that if you didn’t know the TLAs then you probably wouldn’t be able to answer the question.
NDB = Non Directional Beacon
ADF = Automatic Direction Finder
An NDB is a station on the ground puts out a radio signal (either an actual radio station with music, or a morse code ident). An ADF is an instrument in the aircraft which has a card with a compass rose and a needle that points to the NDB. Like LSLGuy says, they are an old outdated technology, though still better than nothing.
A VOR is a more modern piece of equipment that consists of a radio station on the ground transmiting a phase encoded signal. The instrument in the aircraft can tell what the bearing is from or to the radio station. You can gain the same information from the ADF in conjunction with the aircraft’s compass but it requires some mental gymnastics and is not portrayed in the same user friendly way as the VOR.
I’m interested in how far down the road the US has gone in phasing out the NDBs and moving to a system which has VORs only.
Australia still has a large number of NDBs around the country.
The GA airport I fly from has an NDB. Technically, it is out of service, and the instrument approcah is VOR/DME. In the real world I use the NDB all the time (tho I’m VFR only)
My closest airport wouldn’t have that info for the USA :). I do wish that we still had the location field.
I had always been vaguely aware that the US had very few NDBs left in service. It was not until I saw the pic of the Seminole that it hit me that you have so few NDBs that some people would actually not bother having an ADF as part of their instrument kit.
GPS Non Precision Approaches are gaining ground here but are not all that common yet. Pretty much all domestic airlines fly to several destinations which only have an NDB.
IANAP, but I do make IAPs so I can help a little. I looked through 7 of the 24 FAA IAP books and found three NDB only airports. I also found a number of airports that have NDB or GPS IAPs and a few that had an NDB and GPS charts. I also found a few RNAV (GPS) charts with NDB charts, the RNAV charts replaced the GPS charts and are slowly replacing the rest of them.
Just for reference I found:
Cuba MO (UBX) NDB-A (NC-3)
Glencoe, MN (GYL) NDB RWY 31 (NC-1)
Arco, ID (AOC) NDB-A (NW-1)
I didn’t want to spend the time to go through the rest of the books, that and I don’t want to look like a fool asking the other sections for their books. I’m not sure how soon, if ever, NDBs will be phased out. I did an original chart last year for an NDB only. After all the original RNAVs, the new standard, I didn’t know how to do an original, actually not many people in the office did! The FAA does talk of only using GPS navigation, but that’s not in the near future.
As a point for comparison, I found 17 airfields with only an NDB in the “C” section of the Jeppesen Manual for Australia. I don’t have your patience and so didn’t look through the rest of the Manual.
Almost all of these airfields had GPS NPAs. I’m not really sure how often GPS approaches are used instead of the NDB. I guess the major airlines use them when available.
