xjtguy

MEM, DEN, IAD/DCA, and other airports got them recently, I'm sure there's a lot more to come.

They're "the latest thing".

Seems as if they're like RNAV departures at times. Spend all the time briefing them and making sure the FMS is set up correctly, only to have the controllers break you off, assign a hard altitude instead of the window allowed, etc etc etc.

block30

Oh, yep, you're right. Thanks!!

jws3443

Add clt to the list as well...

FL450

I thought the advisory VNAV (snowflake) is not temperature compensated so its not reliable (in the CRj)

higney85

It works pretty slick when you only use it as ADVISORY. There are corrections shown every few thousand feet in a rnav arrival, but the Vnav calculations are normally within +/- 100ft of what you really need, or what would happen with auto throttles and full Vnav certification. Not bad for 1980's technology....

Jetjock65

As speedbird said: Optimized Descent Profile

Not to bust your cajones, but your knowledge
Is lacking!!!!

Red97Vette

The snowflake is for descend vias. Its amazing for those actually. The snowflake "looks through" all the at or above, and at or belows and guides you through them. At XJET we are taught that if you get a descend via, you set the next lowest "hard" altitude (not the at or below, or at or above, but the first "at" only altitude). When you hit that hard altitude keep setting the next "hard" altitude. Then you look for the TOD on the MFD, and when you approach the TOD, the snow flake will appear and you descend to match that. There is no vertical speed descent rate to follow to ride the snowflake down, you have to guess and see what allows you to keep up with the snowflake. A very common mistake is thinking the green data block on the PFD correlates to the snowflake, it does not. The descent angle and the vertical speed that is on the FPD (the green "data block") is ONLY for the the next hard altitudes on the FMS, and does NOT comply with the "at or above" or "at or belows" and will get you into trouble. If you follow the snowflake you will cross usually towards the top of the "windows" on the descent vias. You also have to watch the snowflake like a hawk to keep it from getting away from you. If you have a strong tail wind on a descent via while using the snowflake you have to be mindful of your groundspeed as use of the spoilers will probably have to be used as your descent rate can get high, especially if you have a slow down associated with your crossing restrictions on the descend via. If ATC vectors you off of the descend via, ALL the data and snowflake info goes out the window. ATC often is not aware of this, so you have to tell ATC that you need a new altitude to descend to, as you could get into trouble because the FMS does not know how to guide you down. You are now kind of descending into nowhere scenario.

Jetjock65

If you have altitude crossings for a dept/arrival the FMS will calculate for advisory vnav. this can be a crossing restriction of an assigned alt "5000", above 5000 "5000A", below "5000B", or between "6000/4000". The Vnav on the mfd will show the next altitude restriction only. If you hit "DIR/INTC" you will see all the Vnav calculations for the extire arr/dept. You can then use the most restrictive of all the points. It never fails that you see 1000fpm for a fix 30 miles out, but then 4,000fpm right after. From 30 out you may just have 1,500 to meet the end restriction. Obviously, you need to hit each "hard" restriction but it works well to show the overall path to assist planning.

Thanks Highney & RedVett
Exactly what I was looking for!!!

Trip7

The snowflake allows you to descend to a hard altitude at a constant 3 degree slope and meet all soft altitude windows. Some places like DCA the snowflake disappears after passing a fix during the descent which simply means to level off.

My ODP arrival briefing is simple and well.... brief. I will descend to the hard altitudes using the snowflake. Once I hit the TOD the snowflake appears, and I divide my ground speed by 2 to get my intial decent rate. I tweak it from there to follow the snowflake.

lolwut

I'm amazed a bunch of professional airline pilots are flying STARs using VNAV in an airplane that is not VNAV equipped... and calling said feature a "snowflake"