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What’s the logic of IFR alternate minimums?


RobertE

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I was taught the same thing - an ILS is the gold standard for an alternate.  Also, if you go missed on a non-precision approach, don't try it again - proceed to your alternate, with its precision approach. 


Our opspecs say to use the lowest alternate minimums which is basically two hundred feet above lowest approach and 1/2 mile better, you have to have two completely separate suitable approaches to two different runways. Two rnavs wouldn’t count because they are the “same facility” same way as an ILS and localizer is, or ILS and it’s backcourse, etc. can’t use an approach to a runway where the winds are outside of limits either etc


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Nantucket is awesome for LIFR!  I flew in there a bunch before and after the TDZ lights were installed (late 90's?), and the heat generated by them was often enough to lift the fog a bit.  Number of missed approaches went way down post-TDZ lighting.  Of course, a switch to LED's will ruin this effect.
-dan


Nantucket airport is where it is because the military needed to train pilots to do low approaches. They picked literally the worst weather foggiest patch of land in the USA. Having said that I’m flying in there four times today, all beautiful VFR so dont jinx me!


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4 hours ago, N201MKTurbo said:

I’ve never been in this situation, but if I was I would pick something like the Air Force base with wide runways and crash, fire and rescue and fly an ILS down to the ground. 

Much better to crash in the landing configuration with somebody standing by to help you then in a random location. Besides there is a good chance you could pull it off unscathed.

In that particular crash the pilot did talk to the tower at the AFB, and the tower indicated that the field could be used for emergencies only.    The pilot was already pretty stressed at that point (he was running out of fuel in heavy IMC as well as dealing with some possible equipment failures) and apparently just heard, "You can't land here."    Given the short period of time until he did run out of fuel and the weather conditions at the time, he was already in a fuel emergency and the logical thing would have been to go to the AFB.

IIRC the NTSB dinged the AFB tower controller for that in the final report, that the tone, or whatever, in the discussion may have contributed to the crash by dissuading the pilot from landing there in the middle of an emergency.

 

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The idea behind the alternate minimums is that the pilot doesn’t pick 2 “hard ifr” airports.  200’ and 1/2 a mile is a HUGE difference from a snoozer-like 800/2...

i think the “logic” behind the minimums was to give the pilot the “mandate” to pick an alternate, but also the “leash” to plan for his/her area of flight... basically good old fashioned flexibility.  

Heres what I mean...

On the east coast, widespread low IFR is certainly “a thing.”  But in places like central Oregon, or central California, it typically is not.  By having the minimums set at “not severe clear” it gives a pilot that operates in an area like central Oregon the flexibility to plan to a 200-1/2 minimum, and use an alternate that’s still IFR, but predictably to a higher minima.  This phenomenon does exist between valleys, mountains, high desert, etc, etc... all of which may be within a divert radius.

on the east coast.. or at least on the Virginia coast and Florida panhandle... the weather can get very low, over hundreds of miles.  That means it’s up to the PIC to be responsible enough, and accountable enough to take the time to do the proper preflight planning process (not just looking at the iPad and hopping in the plane- but actually calling and speaking to a briefer).

so... with that flexibility comes the responsibility of actually analyzing the situation at hand, and making a smart decision. As opposed to blindly accepting the regulations at face value and planning to put ones self in a potential bad situation.

JMHO

Edited by M016576
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I've only had a couple of opportunities to file to an airport broadcasting minimums. But as an amateur pilot, I'm always looking for the opportunity when it does present its self. The first time I knew I'd have enough fuel to fly there, attempt the approach a few times and then fly all the way home where it would be CAVU all day. Riding the ILS all the way to 200 ft and only just seeing the lights at that point, was as satisfying as my very first solo flight.

It might be because I don't have to do it for a living, but I enjoy flying IFR and IMC.

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11 hours ago, gsxrpilot said:

 

It might be because I don't have to do it for a living, but I enjoy flying IFR and IMC.

I still get a nice sense of accomplishment when I break out after a long flight in IMC.

vfr flight-> 4x4-in’ through the desert

ifr flight-> driving city to city via the interstate.

both are enjoyable in different ways.

The time where it’s not enjoyable (again just imo) is when I accept more risk on a flight than I’d like, and something goes wrong (electrical failure in hard IMC, for example).  

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@gsengle how much does approach lighting practically play into low IFR? Boston can get pretty low but the lights are about as bright as you can ask for. Often I would use Bos as my “legal seafood” alternate when filing to OWD or BED even though there might be better weather at Beverly or Lawrence because the precision approach availability, big runways and great lighting.   

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39 minutes ago, bradp said:

@gsengle how much does approach lighting practically play into low IFR? Boston can get pretty low but the lights are about as bright as you can ask for. Often I would use Bos as my “legal seafood” alternate when filing to OWD or BED even though there might be better weather at Beverly or Lawrence because the precision approach availability, big runways and great lighting.   

Some of the minimums set at fields depend on the approach lighting being operational.  If the approach lighting system is INOP at those fields- you’ll see a note on the plate that raises the approach minima.

practically? On an approach down to minimums you most likely won’t see the runway at minimums: just the “runway environment”... most of the time that’s just the lighting system.

edit: I’m speaking of precision approaches to low minimums (200-1/2)

Edited by M016576
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[mention=8040]gsengle[/mention] how much does approach lighting practically play into low IFR? Boston can get pretty low but the lights are about as bright as you can ask for. Often I would use Bos as my “legal seafood” alternate when filing to OWD or BED even though there might be better weather at Beverly or Lawrence because the precision approach availability, big runways and great lighting.   


Lighting is everything with low approaches. When it’s 2400 RVR or so or less, you won’t have threshold lights in sight at minimums and will have to continue down the additional hundred feet based on the lead in lights. If all the lights aren’t bright you won’t see them at all in that kind of visibility.

Big runways are good because of 1) bigger clear area, 2) just wider and longer 3) usually lead in lights (eg SSALR at ACK 24) and have 4) high intensity with centerline and touchdown zone lights...


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Thank you gentlemen,

For sharing the practical side of the regulations and the logic that goes with it all...

 

And when the brown stuff hits the fan...   big runways and rescue equipment become more available after using the E word...

 

Best regards,

-a-

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Never be afraid of declaring “minimum fuel” or a full blown mayday when the dino juice gets critical. Get as many assets on your side (ATC, etc). Remember survival is the key point here. Get the aircraft safely on the ground and worry about the paperwork later. Many pilots throughout history, large and small aircraft,  met their demise by not using the ace in the pocket. Declare an emergency and get the rubber on the pavement at the nearest suitable airfield.

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