NDB Approach Questions

[your_dreamguy]

Hello Everyone

I was stumped by some NDB refresher questions and was wondering if you could help me out? My company does not do NDB approaches, so, I've forgotten a lot since it's been forever. I have not dealed with NDB's in a very long time.

First, when doing an NDB approach, when do you consider yourself established? For example, when doing a VOR approach, it's when the VOR needle comes in and is less than full deflection. One of my fellow company pilots said that it was 5 degrees or less on the inbound magnetic bearing of the approach. They found their answer in an ASA instrument book. I have not found anything in any other publications.

Second, when do you consider yourself as needing to execute a missed approach? I thought it was if the NDB needle was plus or minus 10 degrees off from the inbound mag heading on the approach. I couldn't remember if the "10 degree" rule was from the Instrument PTS or not?

Look forward to your responses.

 

[EagleRJ]

You are established inbound on an NDB when you are within 10 degrees of the inbound bearing.

You should go missed when your relative bearing to the station is more than 10 degrees from the inbound course. 10 degrees is also the PTS standard.

The FAA is in the process of decommissioning all the NDBs not associated with an ILS approach, and soon you will have to go to Alaska or the South Pacific to find one. I can't wait to tell younger pilots about them in 20 or 30 years. "You guys have it easy! When I was your age....." etc etc.

 

[Lead Sled]

NDB Approach? Isn't that some type of emergency procedure? Oh yeah, I remember now, that's something you do every 6 months in the simulator. I forget why though.

Lead Sled

 

[GravityHater]

You will only have to go as far as Canada, they have a bunch and I bet they don't go away as soon. In fact there are lots of private ndbs in this country that will probably hang around.

 

[Moonfly201]

Bye bye AM Band .....

A bigger loss than the outdated NDB instrument procedures will be the loss of the ADF radios found in many aircraft today.

AM talk radio, sports events, news ... on 9/11 many flight-crews found out what was happening via the trusty old ADF.

When the procedures are gone, the ADF radios will soon follow.

 

[Kaman]

Hello,

I think that you'll see NDBs around for a long time in the Caribbean and other international locales. It is rare to shoot an NDB approach at most of the airports that are served by 121 carriers, but until they are truly all decomissioned I think that an NDB approach is fair game on a PC with some check airman. I don't think that they are a big deal in the sim, because the eratic needle waving behavior characteristic of most NDBs in the US doesn't happen (just in my brief experience in the sim) and with an RMI it's just like a VOR approach. I use the "push the head, pull the tail" method for the RMI and it works well for me.

Regards,

ex-Navy Rotorhead

 

[midlifeflyer]

You are established inbound on an NDB when you are within 10 degrees of the inbound bearing.

This issue came up in another thread.

Wondering whether this 10° is personal opinion, company choice for OpSpec, or a verifiable FAA requirement (other than the PTS -after all, while the base instrument standard is 10°, the ATP standard is 5°)

 

[bafanguy]

Midlifeflyer,


LOL....here we go again !! See what I was talking about re confusion ?

 

[midlifeflyer]

baf..

Yup. But I'll stand by my position. It's only confusing because people are looking for an FAA-sanctioned mathematically precise definition that does not and cannot, for all practical purposes, exist because of the number of variables involved. lawfly gave a great short summary of my long-winded version in the other thread http://forums.flightinfo.com/showpost.php?p=423272&postcount=27

 

[dsee8driver]

Ndb

I just returned from a few weeks flying South America, Colombia to be specific. Crappy weather and mountains, not a good mixture. All we flew into Bogota at night was the NDB DME Approach to 13L. Talk about a pain procedure. Special procedures were all based on NDBs so I don't think they'll go away any time soon.

 

[satpak77]

South America NDB's get interesting when the generator running the beacon runs out of gas or some pigeons sit on top of the antenna site.

My NDB approach technique is put the navaid into the FMS and then put the EFIS bearing pointed to FMS (which is set for the NDB) and use that, with analog NDB backed up on CP side to make it "legal"

the above gives you distance info, wind vector info, etc.

 

[been-there]

South America NDB's get interesting when the generator running the beacon runs out of gas or some pigeons sit on top of the antenna site.

My NDB approach technique is put the navaid into the FMS and then put the EFIS bearing pointed to FMS (which is set for the NDB) and use that, with analog NDB backed up on CP side to make it "legal"

the above gives you distance info, wind vector info, etc.

"Your Dangerous"

 

[EagleRJ]

Wondering whether this 10° is personal opinion, company choice for OpSpec, or a verifiable FAA requirement (other than the PTS -after all, while the base instrument standard is 10°, the ATP standard is 5°)

Does someone have their AIM handy? I'm sure it's in there. I can't find mine.

I remember using +/- 10 degrees all through instrument training, so that number must have come from somewhere other than the PTS. The only reference I was able to find says it is +/- 5 degrees, though, but doesn't reference it.

Trevor Thom's Instrument Flying- p. 29-6
Where no final approach fix is shown, final decent should not be commenced until the airplane is established within +/- 5 degrees of the final approach course.

 

[EagleRJ]

"Your Dangerous"

Your / adjective: of or relating to you or yourself.

You're / conjuction: a word that joins together sentances, clauses, phrases, or words. In this case, a combination of 'you' and 'are'.

 

[OhDannyBoy]

NDB Heaven

Many smaller, poorer caribbean islands will continue the use of NDBs as they are cheaper to operate, monitor and have greater range than VORs at lower altitudes.

nevermind shoreline effect, of course.

 

[midlifeflyer]

Does someone have their AIM handy? I'm sure it's in there. I can't find mine.

I have mine and it's searchable. It's not in the AIM. AFAIK the only AIM reference to 5° deals with the "border" between the recommended holding pattern entries.

I remember using +/- 10 degrees all through instrument training, so that number must have come from somewhere other than the PTS.

Not from an FAA Publication other than the PTS. And why would you think that a tolerance that you used throughout training wouldn't come form the PTS? Isn't that the whole idea of the PTS - to establish tolerances for training and the checkride? Besides, the PTS tolerances deal with permitted deviations from course, not what it means to be established on course when you are intercepting it.

Trevor Thom's Instrument Flying- p. 29-6
Where no final approach fix is shown, final decent should not be commenced until the airplane is established within +/- 5 degrees of the final approach course.

Excellent operating procedure but not official. Besides, notice the wording. He doesn't say you =are= established when within 5° but that you should be established within 5° rather thasn established within 10 or 15 or 60°. (in other words, it doesn't say "final decent should not be commenced until the airplane is within +/- 5 degrees of the final approach course when it is within +/- 5 degrees of the final approach course."

Using the only AIM definition of "established" , it means you should "be stable or fixed on a route, route segment, altitude, heading, etc." within 5° of the course line.