NAV 1, NAV 2 Rule

Yeah... everyone posted sufficient information about this NAV 1, 2 NAV rule. I just needed someone to explain it to me like I am '5' years old. I am still in Aircraft Dispatch school, and just wanted to know what it meant. I heard many airlines wanted their 'new-hires' to have a good idea of what the NAV1 NAV2 rule is.
Thanks for the info. I would like a more basic understanding for the rule if you all could.
 
JayD said:
Yeah... everyone posted sufficient information about this NAV 1, 2 NAV rule. I just needed someone to explain it to me like I am '5' years old. I am still in Aircraft Dispatch school, and just wanted to know what it meant. I heard many airlines wanted their 'new-hires' to have a good idea of what the NAV1 NAV2 rule is.
Thanks for the info. I would like a more basic understanding for the rule if you all could.
Click to expand...
PM sent
 
JayD said:
Yeah... everyone posted sufficient information about this NAV 1, 2 NAV rule. I just needed someone to explain it to me like I am '5' years old. I am still in Aircraft Dispatch school, and just wanted to know what it meant. I heard many airlines wanted their 'new-hires' to have a good idea of what the NAV1 NAV2 rule is.
Thanks for the info. I would like a more basic understanding for the rule if you all could.
Click to expand...

You are absolutely correct! Many employers expect you to know this rule as well as the 1-2-3 Rule.
 
You stated that you had firm grasp on the 121.617 and 121.619, so I won't try to expand on that. 121.619 originates from 91.169. Within 91.169, it states that for an airport to be listed as an Alternate it has to meet the
"airport minima specified in that procedure, or if none are specified the following standard approach minima:
(A) For a precision approach procedure. Ceiling 600 feet and visibility 2 statute miles.
(B) For a nonprecision approach procedure. Ceiling 800 feet and visibility 2 statute miles." These are typically found on the Airport Data pages.

121.619 points towards 121.625 (which allows carriers to deviate from 91.169 per what is defined within the OpSpec). Most all carriers have the 1 Navaid, 2 Navaid rule (and some CAT II/III) to obtain mins lower than the Standard IFR Alternate Minimums.

For Example(assuming no restrictive NOTAMS): I have a flight from FLL-BOS. BOS is currently BKN010 and forecasted to be BKN008 throughout the entire TAF period. All of New England is forecasted to be BKN006-BKN008. Using the Standard IFR Alternate Mins, I'd be looking for an Alternate to list somewhere within NY state area. Using the 1 Navaid, 2 Navaid rule, I can list PVD as my ALT because the ILS 5 and 23 give me 400'-1sm. Side note: listing a far ALT requires more fuel (obviously) and depending on one's airplane performance, you might be bumping a few pax and/or bags.

Hope this helps.
 
Mach82 said:
You stated that you had firm grasp on the 121.617 and 121.619, so I won't try to expand on that. 121.619 originates from 91.169. Within 91.169, it states that for an airport to be listed as an Alternate it has to meet the
"airport minima specified in that procedure, or if none are specified the following standard approach minima:
(A) For a precision approach procedure. Ceiling 600 feet and visibility 2 statute miles.
(B) For a nonprecision approach procedure. Ceiling 800 feet and visibility 2 statute miles." These are typically found on the Airport Data pages.

121.619 points towards 121.625 (which allows carriers to deviate from 91.169 per what is defined within the OpSpec). Most all carriers have the 1 Navaid, 2 Navaid rule (and some CAT II/III) to obtain mins lower than the Standard IFR Alternate Minimums.

For Example(assuming no restrictive NOTAMS): I have a flight from FLL-BOS. BOS is currently BKN010 and forecasted to be BKN008 throughout the entire TAF period. All of New England is forecasted to be BKN006-BKN008. Using the Standard IFR Alternate Mins, I'd be looking for an Alternate to list somewhere within NY state area. Using the 1 Navaid, 2 Navaid rule, I can list PVD as my ALT because the ILS 5 and 23 give me 400'-1sm. Side note: listing a far ALT requires more fuel (obviously) and depending on one's airplane performance, you might be bumping a few pax and/or bags.

Hope this helps.
Click to expand...
Assuming those two approaches use different nav-aids.

Got burned on that on a test when I was brand new and applied two nav-aid rule to a VOR approach. Also when calculating alt mins using the two nav-aid rule you must always use the most restrictive mins. For instance I have landing mins of 300-1/2 and 200-1. I apply 200 to the 300 = 500 and a 1/2 to 1= 1 1/2
 
I think I have an improved understanding now. I will be asking for examples from my flight planning at Jeppesen. This should correct most of my cluttered brain. I thank you all for the basic elaborate information.
Standard alternate weather minimums are 600-2 and 800-2. If allowed by the air carrier to use the NAV1 NAV2 rule, I can check the alternate minimums, apply the math from the NAV1 NAV2 rule, then see if the minimums turn out to be lower than the standard alternate weather minimums.

Correct me if I am wrong.

Thanks all!

P.S. I noticed that everyone had an input of info referring to the NAV1 NAV2 rule. Seems to me that many airlines use different approaches to the basic meaning of the NAV1 NAV2 rule. Correct me if I am incorrect.
 
My only suggestion is to call the rule by it's proper name, not NAV1, NAV2.

It is called "1 Navaid, 2 Navaid Rule"

Might seem like splitting hairs, but the incorrect way is somewhat misleading and might make some people think you're referring to something else.
 
letthatsinkin said:
My only suggestion is to call the rule by it's proper name, not NAV1, NAV2.

It is called "1 Navaid, 2 Navaid Rule"

Might seem like splitting hairs, but the incorrect way is somewhat misleading and might make some people think you're referring to something else.
Click to expand...

I will fix this for the future, especially for future jobs. I am new and studying dispatching at the moment. If anyone can correct me on proper sayings during my forum posting, or 'on the job', I am much appreciated for their correction.
 
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