DME arcs and 3:1

[RichardRambone]

Could someone explain to me the 3:1 rule and how to figure distance between points on a DME arc. Did a search with no luck and I have an interview coming up. Also whats difference b/w FAF and FAP? Any info would be fantastic.

 

[BobbyBiplane]

Could someone explain to me the 3:1 rule and how to figure distance between points on a DME arc. Did a search with no luck and I have an interview coming up. Also whats difference b/w FAF and FAP? Any info would be fantastic.

What part of Pi did you not learn in high school?

 

[Amish RakeFight]

DME / 60 X degrees


For instance:

12 DME Arc

between radials 010 and 090

12/60 = .02 X 80 = 16 miles


So if you've maintainedthe 12 DME arc from the 010 radial to the 090 radial, you travelled 16 miles.

 

[ohplease!]

Could someone explain to me the 3:1 rule and how to figure distance between points on a DME arc. Did a search with no luck and I have an interview coming up. Also whats difference b/w FAF and FAP? Any info would be fantastic.

one word: FMS (maybe thats three words).... sorry, wish I could help.

 

[crxpilot]

Could someone explain to me the 3:1 rule and how to figure distance between points on a DME arc. Did a search with no luck and I have an interview coming up. Also whats difference b/w FAF and FAP? Any info would be fantastic.

Google 101:

dme arcs: http://stoenworks.com/Tutorials/IFR, VOR-DME Approaches.html

FAF and FAP: http://www.flightsimaviation.com/aviation_theory_15_Instrument_Approach_Procedures_part_1.html

3:1 rule: http://www.avtrial.com/descent-planning.html

 

[Amish RakeFight]

3:1 Rule

Basically, you multiply the altitude you need to lose by 3.

20,000' down to 5,000' = 15,000' to lose.

3 X 15 = 45

45 miles out you begin a descent.
(It's best to add a few miles as a fudge factor and for any level off at 10K for 250 below)

For descent rate, cut your ground speed by 2
400 knots / 2 = 200 or 2000 FPM

 

[RichardRambone]

Thanks guys. I'll add it to the file.

 

[Brett Hull]

...how to figure distance between points on a DME arc.

And you would need to know this in the real world because???

 

[Americam]

And you would need to know this in the real world because???

You don't, but for some reason some FAA inspectors still ask this DME-arc-distance crap on instrument checks (got 'em on both my instrument checkride and my CFI-I checkride.) I can't imagine any airline interviews would ask this stuff.

 

[vectorvictor]

Are you guys talking about airplanes or a recipe for sugar cookies?